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llvm-project/clang/lib/Sema/AnalysisBasedWarnings.cpp

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//=- AnalysisBasedWarnings.cpp - Sema warnings based on libAnalysis -*- C++ -*-=//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines analysis_warnings::[Policy,Executor].
// Together they are used by Sema to issue warnings based on inexpensive
// static analysis algorithms in libAnalysis.
//
//===----------------------------------------------------------------------===//
#include "clang/Sema/AnalysisBasedWarnings.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/EvaluatedExprVisitor.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/ParentMap.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/StmtCXX.h"
#include "clang/AST/StmtObjC.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/Analysis/Analyses/CFGReachabilityAnalysis.h"
#include "clang/Analysis/Analyses/Consumed.h"
#include "clang/Analysis/Analyses/ReachableCode.h"
#include "clang/Analysis/Analyses/ThreadSafety.h"
#include "clang/Analysis/Analyses/UninitializedValues.h"
#include "clang/Analysis/AnalysisDeclContext.h"
#include "clang/Analysis/CFG.h"
#include "clang/Analysis/CFGStmtMap.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/SemaInternal.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Casting.h"
#include <algorithm>
#include <deque>
#include <iterator>
using namespace clang;
//===----------------------------------------------------------------------===//
// Unreachable code analysis.
//===----------------------------------------------------------------------===//
namespace {
class UnreachableCodeHandler : public reachable_code::Callback {
Sema &S;
SourceRange PreviousSilenceableCondVal;
public:
UnreachableCodeHandler(Sema &s) : S(s) {}
void HandleUnreachable(reachable_code::UnreachableKind UK,
SourceLocation L,
SourceRange SilenceableCondVal,
SourceRange R1,
SourceRange R2) override {
// Avoid reporting multiple unreachable code diagnostics that are
// triggered by the same conditional value.
if (PreviousSilenceableCondVal.isValid() &&
SilenceableCondVal.isValid() &&
PreviousSilenceableCondVal == SilenceableCondVal)
return;
PreviousSilenceableCondVal = SilenceableCondVal;
unsigned diag = diag::warn_unreachable;
switch (UK) {
case reachable_code::UK_Break:
diag = diag::warn_unreachable_break;
break;
case reachable_code::UK_Return:
diag = diag::warn_unreachable_return;
break;
case reachable_code::UK_Loop_Increment:
diag = diag::warn_unreachable_loop_increment;
break;
case reachable_code::UK_Other:
break;
}
S.Diag(L, diag) << R1 << R2;
SourceLocation Open = SilenceableCondVal.getBegin();
if (Open.isValid()) {
SourceLocation Close = SilenceableCondVal.getEnd();
Close = S.getLocForEndOfToken(Close);
if (Close.isValid()) {
S.Diag(Open, diag::note_unreachable_silence)
<< FixItHint::CreateInsertion(Open, "/* DISABLES CODE */ (")
<< FixItHint::CreateInsertion(Close, ")");
}
}
}
};
} // anonymous namespace
/// CheckUnreachable - Check for unreachable code.
static void CheckUnreachable(Sema &S, AnalysisDeclContext &AC) {
// As a heuristic prune all diagnostics not in the main file. Currently
// the majority of warnings in headers are false positives. These
// are largely caused by configuration state, e.g. preprocessor
// defined code, etc.
//
// Note that this is also a performance optimization. Analyzing
// headers many times can be expensive.
if (!S.getSourceManager().isInMainFile(AC.getDecl()->getLocStart()))
return;
UnreachableCodeHandler UC(S);
reachable_code::FindUnreachableCode(AC, S.getPreprocessor(), UC);
}
namespace {
/// \brief Warn on logical operator errors in CFGBuilder
class LogicalErrorHandler : public CFGCallback {
Sema &S;
public:
LogicalErrorHandler(Sema &S) : CFGCallback(), S(S) {}
static bool HasMacroID(const Expr *E) {
if (E->getExprLoc().isMacroID())
return true;
// Recurse to children.
for (const Stmt *SubStmt : E->children())
if (const Expr *SubExpr = dyn_cast_or_null<Expr>(SubStmt))
if (HasMacroID(SubExpr))
return true;
return false;
}
void compareAlwaysTrue(const BinaryOperator *B, bool isAlwaysTrue) override {
if (HasMacroID(B))
return;
SourceRange DiagRange = B->getSourceRange();
S.Diag(B->getExprLoc(), diag::warn_tautological_overlap_comparison)
<< DiagRange << isAlwaysTrue;
}
void compareBitwiseEquality(const BinaryOperator *B,
bool isAlwaysTrue) override {
if (HasMacroID(B))
return;
SourceRange DiagRange = B->getSourceRange();
S.Diag(B->getExprLoc(), diag::warn_comparison_bitwise_always)
<< DiagRange << isAlwaysTrue;
}
};
} // anonymous namespace
//===----------------------------------------------------------------------===//
// Check for infinite self-recursion in functions
//===----------------------------------------------------------------------===//
// Returns true if the function is called anywhere within the CFGBlock.
// For member functions, the additional condition of being call from the
// this pointer is required.
static bool hasRecursiveCallInPath(const FunctionDecl *FD, CFGBlock &Block) {
// Process all the Stmt's in this block to find any calls to FD.
for (const auto &B : Block) {
if (B.getKind() != CFGElement::Statement)
continue;
const CallExpr *CE = dyn_cast<CallExpr>(B.getAs<CFGStmt>()->getStmt());
if (!CE || !CE->getCalleeDecl() ||
CE->getCalleeDecl()->getCanonicalDecl() != FD)
continue;
// Skip function calls which are qualified with a templated class.
if (const DeclRefExpr *DRE =
dyn_cast<DeclRefExpr>(CE->getCallee()->IgnoreParenImpCasts())) {
if (NestedNameSpecifier *NNS = DRE->getQualifier()) {
if (NNS->getKind() == NestedNameSpecifier::TypeSpec &&
isa<TemplateSpecializationType>(NNS->getAsType())) {
continue;
}
}
}
const CXXMemberCallExpr *MCE = dyn_cast<CXXMemberCallExpr>(CE);
if (!MCE || isa<CXXThisExpr>(MCE->getImplicitObjectArgument()) ||
!MCE->getMethodDecl()->isVirtual())
return true;
}
return false;
}
// All blocks are in one of three states. States are ordered so that blocks
// can only move to higher states.
enum RecursiveState {
FoundNoPath,
FoundPath,
FoundPathWithNoRecursiveCall
};
// Returns true if there exists a path to the exit block and every path
// to the exit block passes through a call to FD.
static bool checkForRecursiveFunctionCall(const FunctionDecl *FD, CFG *cfg) {
const unsigned ExitID = cfg->getExit().getBlockID();
// Mark all nodes as FoundNoPath, then set the status of the entry block.
SmallVector<RecursiveState, 16> States(cfg->getNumBlockIDs(), FoundNoPath);
States[cfg->getEntry().getBlockID()] = FoundPathWithNoRecursiveCall;
// Make the processing stack and seed it with the entry block.
SmallVector<CFGBlock *, 16> Stack;
Stack.push_back(&cfg->getEntry());
while (!Stack.empty()) {
CFGBlock *CurBlock = Stack.back();
Stack.pop_back();
unsigned ID = CurBlock->getBlockID();
RecursiveState CurState = States[ID];
if (CurState == FoundPathWithNoRecursiveCall) {
// Found a path to the exit node without a recursive call.
if (ExitID == ID)
return false;
// Only change state if the block has a recursive call.
if (hasRecursiveCallInPath(FD, *CurBlock))
CurState = FoundPath;
}
// Loop over successor blocks and add them to the Stack if their state
// changes.
for (auto I = CurBlock->succ_begin(), E = CurBlock->succ_end(); I != E; ++I)
if (*I) {
unsigned next_ID = (*I)->getBlockID();
if (States[next_ID] < CurState) {
States[next_ID] = CurState;
Stack.push_back(*I);
}
}
}
// Return true if the exit node is reachable, and only reachable through
// a recursive call.
return States[ExitID] == FoundPath;
}
static void checkRecursiveFunction(Sema &S, const FunctionDecl *FD,
const Stmt *Body, AnalysisDeclContext &AC) {
FD = FD->getCanonicalDecl();
// Only run on non-templated functions and non-templated members of
// templated classes.
if (FD->getTemplatedKind() != FunctionDecl::TK_NonTemplate &&
FD->getTemplatedKind() != FunctionDecl::TK_MemberSpecialization)
return;
CFG *cfg = AC.getCFG();
if (!cfg) return;
// If the exit block is unreachable, skip processing the function.
if (cfg->getExit().pred_empty())
return;
// Emit diagnostic if a recursive function call is detected for all paths.
if (checkForRecursiveFunctionCall(FD, cfg))
S.Diag(Body->getLocStart(), diag::warn_infinite_recursive_function);
}
//===----------------------------------------------------------------------===//
// Check for throw in a non-throwing function.
//===----------------------------------------------------------------------===//
enum ThrowState {
FoundNoPathForThrow,
FoundPathForThrow,
FoundPathWithNoThrowOutFunction,
};
static bool isThrowCaught(const CXXThrowExpr *Throw,
const CXXCatchStmt *Catch) {
const Type *CaughtType = Catch->getCaughtType().getTypePtrOrNull();
if (!CaughtType)
return true;
const Type *ThrowType = nullptr;
if (Throw->getSubExpr())
ThrowType = Throw->getSubExpr()->getType().getTypePtrOrNull();
if (!ThrowType)
return false;
if (ThrowType->isReferenceType())
ThrowType = ThrowType->castAs<ReferenceType>()
->getPointeeType()
->getUnqualifiedDesugaredType();
if (CaughtType->isReferenceType())
CaughtType = CaughtType->castAs<ReferenceType>()
->getPointeeType()
->getUnqualifiedDesugaredType();
if (ThrowType->isPointerType() && CaughtType->isPointerType()) {
ThrowType = ThrowType->getPointeeType()->getUnqualifiedDesugaredType();
CaughtType = CaughtType->getPointeeType()->getUnqualifiedDesugaredType();
}
if (CaughtType == ThrowType)
return true;
const CXXRecordDecl *CaughtAsRecordType =
CaughtType->getAsCXXRecordDecl();
const CXXRecordDecl *ThrowTypeAsRecordType = ThrowType->getAsCXXRecordDecl();
if (CaughtAsRecordType && ThrowTypeAsRecordType)
return ThrowTypeAsRecordType->isDerivedFrom(CaughtAsRecordType);
return false;
}
static bool isThrowCaughtByHandlers(const CXXThrowExpr *CE,
const CXXTryStmt *TryStmt) {
for (unsigned H = 0, E = TryStmt->getNumHandlers(); H < E; ++H) {
if (isThrowCaught(CE, TryStmt->getHandler(H)))
return true;
}
return false;
}
static bool doesThrowEscapePath(CFGBlock Block, SourceLocation &OpLoc) {
for (const auto &B : Block) {
if (B.getKind() != CFGElement::Statement)
continue;
const auto *CE = dyn_cast<CXXThrowExpr>(B.getAs<CFGStmt>()->getStmt());
if (!CE)
continue;
OpLoc = CE->getThrowLoc();
for (const auto &I : Block.succs()) {
if (!I.isReachable())
continue;
if (const auto *Terminator =
dyn_cast_or_null<CXXTryStmt>(I->getTerminator()))
if (isThrowCaughtByHandlers(CE, Terminator))
return false;
}
return true;
}
return false;
}
static bool hasThrowOutNonThrowingFunc(SourceLocation &OpLoc, CFG *BodyCFG) {
unsigned ExitID = BodyCFG->getExit().getBlockID();
SmallVector<ThrowState, 16> States(BodyCFG->getNumBlockIDs(),
FoundNoPathForThrow);
States[BodyCFG->getEntry().getBlockID()] = FoundPathWithNoThrowOutFunction;
SmallVector<CFGBlock *, 16> Stack;
Stack.push_back(&BodyCFG->getEntry());
while (!Stack.empty()) {
CFGBlock *CurBlock = Stack.pop_back_val();
unsigned ID = CurBlock->getBlockID();
ThrowState CurState = States[ID];
if (CurState == FoundPathWithNoThrowOutFunction) {
if (ExitID == ID)
continue;
if (doesThrowEscapePath(*CurBlock, OpLoc))
CurState = FoundPathForThrow;
}
// Loop over successor blocks and add them to the Stack if their state
// changes.
for (const auto &I : CurBlock->succs())
if (I.isReachable()) {
unsigned NextID = I->getBlockID();
if (NextID == ExitID && CurState == FoundPathForThrow) {
States[NextID] = CurState;
} else if (States[NextID] < CurState) {
States[NextID] = CurState;
Stack.push_back(I);
}
}
}
// Return true if the exit node is reachable, and only reachable through
// a throw expression.
return States[ExitID] == FoundPathForThrow;
}
static void EmitDiagForCXXThrowInNonThrowingFunc(Sema &S, SourceLocation OpLoc,
const FunctionDecl *FD) {
if (!S.getSourceManager().isInSystemHeader(OpLoc) &&
FD->getTypeSourceInfo()) {
S.Diag(OpLoc, diag::warn_throw_in_noexcept_func) << FD;
if (S.getLangOpts().CPlusPlus11 &&
(isa<CXXDestructorDecl>(FD) ||
FD->getDeclName().getCXXOverloadedOperator() == OO_Delete ||
FD->getDeclName().getCXXOverloadedOperator() == OO_Array_Delete)) {
if (const auto *Ty = FD->getTypeSourceInfo()->getType()->
getAs<FunctionProtoType>())
S.Diag(FD->getLocation(), diag::note_throw_in_dtor)
<< !isa<CXXDestructorDecl>(FD) << !Ty->hasExceptionSpec()
<< FD->getExceptionSpecSourceRange();
} else
S.Diag(FD->getLocation(), diag::note_throw_in_function)
<< FD->getExceptionSpecSourceRange();
}
}
static void checkThrowInNonThrowingFunc(Sema &S, const FunctionDecl *FD,
AnalysisDeclContext &AC) {
CFG *BodyCFG = AC.getCFG();
if (!BodyCFG)
return;
if (BodyCFG->getExit().pred_empty())
return;
SourceLocation OpLoc;
if (hasThrowOutNonThrowingFunc(OpLoc, BodyCFG))
EmitDiagForCXXThrowInNonThrowingFunc(S, OpLoc, FD);
}
static bool isNoexcept(const FunctionDecl *FD) {
const auto *FPT = FD->getType()->castAs<FunctionProtoType>();
if (FPT->isNothrow(FD->getASTContext()) || FD->hasAttr<NoThrowAttr>())
return true;
return false;
}
//===----------------------------------------------------------------------===//
// Check for missing return value.
//===----------------------------------------------------------------------===//
enum ControlFlowKind {
UnknownFallThrough,
NeverFallThrough,
MaybeFallThrough,
AlwaysFallThrough,
NeverFallThroughOrReturn
};
/// CheckFallThrough - Check that we don't fall off the end of a
/// Statement that should return a value.
///
/// \returns AlwaysFallThrough iff we always fall off the end of the statement,
/// MaybeFallThrough iff we might or might not fall off the end,
/// NeverFallThroughOrReturn iff we never fall off the end of the statement or
/// return. We assume NeverFallThrough iff we never fall off the end of the
/// statement but we may return. We assume that functions not marked noreturn
/// will return.
static ControlFlowKind CheckFallThrough(AnalysisDeclContext &AC) {
CFG *cfg = AC.getCFG();
if (!cfg) return UnknownFallThrough;
// The CFG leaves in dead things, and we don't want the dead code paths to
// confuse us, so we mark all live things first.
llvm::BitVector live(cfg->getNumBlockIDs());
unsigned count = reachable_code::ScanReachableFromBlock(&cfg->getEntry(),
live);
bool AddEHEdges = AC.getAddEHEdges();
if (!AddEHEdges && count != cfg->getNumBlockIDs())
// When there are things remaining dead, and we didn't add EH edges
// from CallExprs to the catch clauses, we have to go back and
// mark them as live.
for (const auto *B : *cfg) {
if (!live[B->getBlockID()]) {
if (B->pred_begin() == B->pred_end()) {
if (B->getTerminator() && isa<CXXTryStmt>(B->getTerminator()))
// When not adding EH edges from calls, catch clauses
// can otherwise seem dead. Avoid noting them as dead.
count += reachable_code::ScanReachableFromBlock(B, live);
continue;
}
}
}
// Now we know what is live, we check the live precessors of the exit block
// and look for fall through paths, being careful to ignore normal returns,
// and exceptional paths.
bool HasLiveReturn = false;
bool HasFakeEdge = false;
bool HasPlainEdge = false;
bool HasAbnormalEdge = false;
// Ignore default cases that aren't likely to be reachable because all
// enums in a switch(X) have explicit case statements.
CFGBlock::FilterOptions FO;
FO.IgnoreDefaultsWithCoveredEnums = 1;
for (CFGBlock::filtered_pred_iterator
I = cfg->getExit().filtered_pred_start_end(FO); I.hasMore(); ++I) {
const CFGBlock& B = **I;
if (!live[B.getBlockID()])
continue;
// Skip blocks which contain an element marked as no-return. They don't
// represent actually viable edges into the exit block, so mark them as
// abnormal.
if (B.hasNoReturnElement()) {
HasAbnormalEdge = true;
continue;
}
// Destructors can appear after the 'return' in the CFG. This is
// normal. We need to look pass the destructors for the return
// statement (if it exists).
CFGBlock::const_reverse_iterator ri = B.rbegin(), re = B.rend();
for ( ; ri != re ; ++ri)
if (ri->getAs<CFGStmt>())
break;
// No more CFGElements in the block?
if (ri == re) {
if (B.getTerminator() && isa<CXXTryStmt>(B.getTerminator())) {
HasAbnormalEdge = true;
continue;
}
// A labeled empty statement, or the entry block...
HasPlainEdge = true;
continue;
}
CFGStmt CS = ri->castAs<CFGStmt>();
const Stmt *S = CS.getStmt();
if (isa<ReturnStmt>(S) || isa<CoreturnStmt>(S)) {
HasLiveReturn = true;
continue;
}
if (isa<ObjCAtThrowStmt>(S)) {
HasFakeEdge = true;
continue;
}
if (isa<CXXThrowExpr>(S)) {
HasFakeEdge = true;
continue;
}
if (isa<MSAsmStmt>(S)) {
// TODO: Verify this is correct.
HasFakeEdge = true;
HasLiveReturn = true;
continue;
}
if (isa<CXXTryStmt>(S)) {
HasAbnormalEdge = true;
continue;
}
if (std::find(B.succ_begin(), B.succ_end(), &cfg->getExit())
== B.succ_end()) {
HasAbnormalEdge = true;
continue;
}
HasPlainEdge = true;
}
if (!HasPlainEdge) {
if (HasLiveReturn)
return NeverFallThrough;
return NeverFallThroughOrReturn;
}
if (HasAbnormalEdge || HasFakeEdge || HasLiveReturn)
return MaybeFallThrough;
// This says AlwaysFallThrough for calls to functions that are not marked
// noreturn, that don't return. If people would like this warning to be more
// accurate, such functions should be marked as noreturn.
return AlwaysFallThrough;
}
namespace {
struct CheckFallThroughDiagnostics {
unsigned diag_MaybeFallThrough_HasNoReturn;
unsigned diag_MaybeFallThrough_ReturnsNonVoid;
unsigned diag_AlwaysFallThrough_HasNoReturn;
unsigned diag_AlwaysFallThrough_ReturnsNonVoid;
unsigned diag_NeverFallThroughOrReturn;
enum { Function, Block, Lambda, Coroutine } funMode;
SourceLocation FuncLoc;
static CheckFallThroughDiagnostics MakeForFunction(const Decl *Func) {
CheckFallThroughDiagnostics D;
D.FuncLoc = Func->getLocation();
D.diag_MaybeFallThrough_HasNoReturn =
diag::warn_falloff_noreturn_function;
D.diag_MaybeFallThrough_ReturnsNonVoid =
diag::warn_maybe_falloff_nonvoid_function;
D.diag_AlwaysFallThrough_HasNoReturn =
diag::warn_falloff_noreturn_function;
D.diag_AlwaysFallThrough_ReturnsNonVoid =
diag::warn_falloff_nonvoid_function;
// Don't suggest that virtual functions be marked "noreturn", since they
// might be overridden by non-noreturn functions.
bool isVirtualMethod = false;
if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Func))
isVirtualMethod = Method->isVirtual();
// Don't suggest that template instantiations be marked "noreturn"
bool isTemplateInstantiation = false;
if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(Func))
isTemplateInstantiation = Function->isTemplateInstantiation();
if (!isVirtualMethod && !isTemplateInstantiation)
D.diag_NeverFallThroughOrReturn =
diag::warn_suggest_noreturn_function;
else
D.diag_NeverFallThroughOrReturn = 0;
D.funMode = Function;
return D;
}
static CheckFallThroughDiagnostics MakeForCoroutine(const Decl *Func) {
CheckFallThroughDiagnostics D;
D.FuncLoc = Func->getLocation();
D.diag_MaybeFallThrough_HasNoReturn = 0;
D.diag_MaybeFallThrough_ReturnsNonVoid =
diag::warn_maybe_falloff_nonvoid_coroutine;
D.diag_AlwaysFallThrough_HasNoReturn = 0;
D.diag_AlwaysFallThrough_ReturnsNonVoid =
diag::warn_falloff_nonvoid_coroutine;
D.funMode = Coroutine;
return D;
}
static CheckFallThroughDiagnostics MakeForBlock() {
CheckFallThroughDiagnostics D;
D.diag_MaybeFallThrough_HasNoReturn =
diag::err_noreturn_block_has_return_expr;
D.diag_MaybeFallThrough_ReturnsNonVoid =
diag::err_maybe_falloff_nonvoid_block;
D.diag_AlwaysFallThrough_HasNoReturn =
diag::err_noreturn_block_has_return_expr;
D.diag_AlwaysFallThrough_ReturnsNonVoid =
diag::err_falloff_nonvoid_block;
D.diag_NeverFallThroughOrReturn = 0;
D.funMode = Block;
return D;
}
static CheckFallThroughDiagnostics MakeForLambda() {
CheckFallThroughDiagnostics D;
D.diag_MaybeFallThrough_HasNoReturn =
diag::err_noreturn_lambda_has_return_expr;
D.diag_MaybeFallThrough_ReturnsNonVoid =
diag::warn_maybe_falloff_nonvoid_lambda;
D.diag_AlwaysFallThrough_HasNoReturn =
diag::err_noreturn_lambda_has_return_expr;
D.diag_AlwaysFallThrough_ReturnsNonVoid =
diag::warn_falloff_nonvoid_lambda;
D.diag_NeverFallThroughOrReturn = 0;
D.funMode = Lambda;
return D;
}
bool checkDiagnostics(DiagnosticsEngine &D, bool ReturnsVoid,
bool HasNoReturn) const {
if (funMode == Function) {
return (ReturnsVoid ||
D.isIgnored(diag::warn_maybe_falloff_nonvoid_function,
FuncLoc)) &&
(!HasNoReturn ||
D.isIgnored(diag::warn_noreturn_function_has_return_expr,
FuncLoc)) &&
(!ReturnsVoid ||
D.isIgnored(diag::warn_suggest_noreturn_block, FuncLoc));
}
if (funMode == Coroutine) {
return (ReturnsVoid ||
D.isIgnored(diag::warn_maybe_falloff_nonvoid_function, FuncLoc) ||
D.isIgnored(diag::warn_maybe_falloff_nonvoid_coroutine,
FuncLoc)) &&
(!HasNoReturn);
}
// For blocks / lambdas.
return ReturnsVoid && !HasNoReturn;
}
};
} // anonymous namespace
/// CheckFallThroughForFunctionDef - Check that we don't fall off the end of a
/// function that should return a value. Check that we don't fall off the end
/// of a noreturn function. We assume that functions and blocks not marked
/// noreturn will return.
static void CheckFallThroughForBody(Sema &S, const Decl *D, const Stmt *Body,
const BlockExpr *blkExpr,
const CheckFallThroughDiagnostics& CD,
AnalysisDeclContext &AC) {
bool ReturnsVoid = false;
bool HasNoReturn = false;
bool IsCoroutine = S.getCurFunction() && S.getCurFunction()->isCoroutine();
if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
if (const auto *CBody = dyn_cast<CoroutineBodyStmt>(Body))
ReturnsVoid = CBody->getFallthroughHandler() != nullptr;
else
ReturnsVoid = FD->getReturnType()->isVoidType();
HasNoReturn = FD->isNoReturn();
}
else if (const auto *MD = dyn_cast<ObjCMethodDecl>(D)) {
ReturnsVoid = MD->getReturnType()->isVoidType();
HasNoReturn = MD->hasAttr<NoReturnAttr>();
}
else if (isa<BlockDecl>(D)) {
QualType BlockTy = blkExpr->getType();
if (const FunctionType *FT =
BlockTy->getPointeeType()->getAs<FunctionType>()) {
if (FT->getReturnType()->isVoidType())
ReturnsVoid = true;
if (FT->getNoReturnAttr())
HasNoReturn = true;
}
}
DiagnosticsEngine &Diags = S.getDiagnostics();
// Short circuit for compilation speed.
if (CD.checkDiagnostics(Diags, ReturnsVoid, HasNoReturn))
return;
SourceLocation LBrace = Body->getLocStart(), RBrace = Body->getLocEnd();
auto EmitDiag = [&](SourceLocation Loc, unsigned DiagID) {
if (IsCoroutine)
S.Diag(Loc, DiagID) << S.getCurFunction()->CoroutinePromise->getType();
else
S.Diag(Loc, DiagID);
};
// Either in a function body compound statement, or a function-try-block.
switch (CheckFallThrough(AC)) {
case UnknownFallThrough:
break;
case MaybeFallThrough:
if (HasNoReturn)
EmitDiag(RBrace, CD.diag_MaybeFallThrough_HasNoReturn);
else if (!ReturnsVoid)
EmitDiag(RBrace, CD.diag_MaybeFallThrough_ReturnsNonVoid);
break;
case AlwaysFallThrough:
if (HasNoReturn)
EmitDiag(RBrace, CD.diag_AlwaysFallThrough_HasNoReturn);
else if (!ReturnsVoid)
EmitDiag(RBrace, CD.diag_AlwaysFallThrough_ReturnsNonVoid);
break;
case NeverFallThroughOrReturn:
if (ReturnsVoid && !HasNoReturn && CD.diag_NeverFallThroughOrReturn) {
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
S.Diag(LBrace, CD.diag_NeverFallThroughOrReturn) << 0 << FD;
} else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
S.Diag(LBrace, CD.diag_NeverFallThroughOrReturn) << 1 << MD;
} else {
S.Diag(LBrace, CD.diag_NeverFallThroughOrReturn);
}
}
break;
case NeverFallThrough:
break;
}
}
//===----------------------------------------------------------------------===//
// -Wuninitialized
//===----------------------------------------------------------------------===//
namespace {
/// ContainsReference - A visitor class to search for references to
/// a particular declaration (the needle) within any evaluated component of an
/// expression (recursively).
class ContainsReference : public ConstEvaluatedExprVisitor<ContainsReference> {
bool FoundReference;
const DeclRefExpr *Needle;
public:
typedef ConstEvaluatedExprVisitor<ContainsReference> Inherited;
ContainsReference(ASTContext &Context, const DeclRefExpr *Needle)
: Inherited(Context), FoundReference(false), Needle(Needle) {}
void VisitExpr(const Expr *E) {
// Stop evaluating if we already have a reference.
if (FoundReference)
return;
Inherited::VisitExpr(E);
}
void VisitDeclRefExpr(const DeclRefExpr *E) {
if (E == Needle)
FoundReference = true;
else
Inherited::VisitDeclRefExpr(E);
}
bool doesContainReference() const { return FoundReference; }
};
} // anonymous namespace
static bool SuggestInitializationFixit(Sema &S, const VarDecl *VD) {
QualType VariableTy = VD->getType().getCanonicalType();
if (VariableTy->isBlockPointerType() &&
!VD->hasAttr<BlocksAttr>()) {
S.Diag(VD->getLocation(), diag::note_block_var_fixit_add_initialization)
<< VD->getDeclName()
<< FixItHint::CreateInsertion(VD->getLocation(), "__block ");
return true;
}
// Don't issue a fixit if there is already an initializer.
if (VD->getInit())
return false;
// Don't suggest a fixit inside macros.
if (VD->getLocEnd().isMacroID())
return false;
SourceLocation Loc = S.getLocForEndOfToken(VD->getLocEnd());
// Suggest possible initialization (if any).
std::string Init = S.getFixItZeroInitializerForType(VariableTy, Loc);
if (Init.empty())
return false;
S.Diag(Loc, diag::note_var_fixit_add_initialization) << VD->getDeclName()
<< FixItHint::CreateInsertion(Loc, Init);
return true;
}
/// Create a fixit to remove an if-like statement, on the assumption that its
/// condition is CondVal.
static void CreateIfFixit(Sema &S, const Stmt *If, const Stmt *Then,
const Stmt *Else, bool CondVal,
FixItHint &Fixit1, FixItHint &Fixit2) {
if (CondVal) {
// If condition is always true, remove all but the 'then'.
Fixit1 = FixItHint::CreateRemoval(
CharSourceRange::getCharRange(If->getLocStart(),
Then->getLocStart()));
if (Else) {
SourceLocation ElseKwLoc = S.getLocForEndOfToken(Then->getLocEnd());
Fixit2 = FixItHint::CreateRemoval(
SourceRange(ElseKwLoc, Else->getLocEnd()));
}
} else {
// If condition is always false, remove all but the 'else'.
if (Else)
Fixit1 = FixItHint::CreateRemoval(
CharSourceRange::getCharRange(If->getLocStart(),
Else->getLocStart()));
else
Fixit1 = FixItHint::CreateRemoval(If->getSourceRange());
}
}
/// DiagUninitUse -- Helper function to produce a diagnostic for an
/// uninitialized use of a variable.
static void DiagUninitUse(Sema &S, const VarDecl *VD, const UninitUse &Use,
bool IsCapturedByBlock) {
bool Diagnosed = false;
switch (Use.getKind()) {
case UninitUse::Always:
S.Diag(Use.getUser()->getLocStart(), diag::warn_uninit_var)
<< VD->getDeclName() << IsCapturedByBlock
<< Use.getUser()->getSourceRange();
return;
case UninitUse::AfterDecl:
case UninitUse::AfterCall:
S.Diag(VD->getLocation(), diag::warn_sometimes_uninit_var)
<< VD->getDeclName() << IsCapturedByBlock
<< (Use.getKind() == UninitUse::AfterDecl ? 4 : 5)
<< const_cast<DeclContext*>(VD->getLexicalDeclContext())
<< VD->getSourceRange();
S.Diag(Use.getUser()->getLocStart(), diag::note_uninit_var_use)
<< IsCapturedByBlock << Use.getUser()->getSourceRange();
return;
case UninitUse::Maybe:
case UninitUse::Sometimes:
// Carry on to report sometimes-uninitialized branches, if possible,
// or a 'may be used uninitialized' diagnostic otherwise.
break;
}
// Diagnose each branch which leads to a sometimes-uninitialized use.
for (UninitUse::branch_iterator I = Use.branch_begin(), E = Use.branch_end();
I != E; ++I) {
assert(Use.getKind() == UninitUse::Sometimes);
const Expr *User = Use.getUser();
const Stmt *Term = I->Terminator;
// Information used when building the diagnostic.
unsigned DiagKind;
StringRef Str;
SourceRange Range;
// FixIts to suppress the diagnostic by removing the dead condition.
// For all binary terminators, branch 0 is taken if the condition is true,
// and branch 1 is taken if the condition is false.
int RemoveDiagKind = -1;
const char *FixitStr =
S.getLangOpts().CPlusPlus ? (I->Output ? "true" : "false")
: (I->Output ? "1" : "0");
FixItHint Fixit1, Fixit2;
switch (Term ? Term->getStmtClass() : Stmt::DeclStmtClass) {
default:
// Don't know how to report this. Just fall back to 'may be used
// uninitialized'. FIXME: Can this happen?
continue;
// "condition is true / condition is false".
case Stmt::IfStmtClass: {
const IfStmt *IS = cast<IfStmt>(Term);
DiagKind = 0;
Str = "if";
Range = IS->getCond()->getSourceRange();
RemoveDiagKind = 0;
CreateIfFixit(S, IS, IS->getThen(), IS->getElse(),
I->Output, Fixit1, Fixit2);
break;
}
case Stmt::ConditionalOperatorClass: {
const ConditionalOperator *CO = cast<ConditionalOperator>(Term);
DiagKind = 0;
Str = "?:";
Range = CO->getCond()->getSourceRange();
RemoveDiagKind = 0;
CreateIfFixit(S, CO, CO->getTrueExpr(), CO->getFalseExpr(),
I->Output, Fixit1, Fixit2);
break;
}
case Stmt::BinaryOperatorClass: {
const BinaryOperator *BO = cast<BinaryOperator>(Term);
if (!BO->isLogicalOp())
continue;
DiagKind = 0;
Str = BO->getOpcodeStr();
Range = BO->getLHS()->getSourceRange();
RemoveDiagKind = 0;
if ((BO->getOpcode() == BO_LAnd && I->Output) ||
(BO->getOpcode() == BO_LOr && !I->Output))
// true && y -> y, false || y -> y.
Fixit1 = FixItHint::CreateRemoval(SourceRange(BO->getLocStart(),
BO->getOperatorLoc()));
else
// false && y -> false, true || y -> true.
Fixit1 = FixItHint::CreateReplacement(BO->getSourceRange(), FixitStr);
break;
}
// "loop is entered / loop is exited".
case Stmt::WhileStmtClass:
DiagKind = 1;
Str = "while";
Range = cast<WhileStmt>(Term)->getCond()->getSourceRange();
RemoveDiagKind = 1;
Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
break;
case Stmt::ForStmtClass:
DiagKind = 1;
Str = "for";
Range = cast<ForStmt>(Term)->getCond()->getSourceRange();
RemoveDiagKind = 1;
if (I->Output)
Fixit1 = FixItHint::CreateRemoval(Range);
else
Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
break;
case Stmt::CXXForRangeStmtClass:
if (I->Output == 1) {
// The use occurs if a range-based for loop's body never executes.
// That may be impossible, and there's no syntactic fix for this,
// so treat it as a 'may be uninitialized' case.
continue;
}
DiagKind = 1;
Str = "for";
Range = cast<CXXForRangeStmt>(Term)->getRangeInit()->getSourceRange();
break;
// "condition is true / loop is exited".
case Stmt::DoStmtClass:
DiagKind = 2;
Str = "do";
Range = cast<DoStmt>(Term)->getCond()->getSourceRange();
RemoveDiagKind = 1;
Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
break;
// "switch case is taken".
case Stmt::CaseStmtClass:
DiagKind = 3;
Str = "case";
Range = cast<CaseStmt>(Term)->getLHS()->getSourceRange();
break;
case Stmt::DefaultStmtClass:
DiagKind = 3;
Str = "default";
Range = cast<DefaultStmt>(Term)->getDefaultLoc();
break;
}
S.Diag(Range.getBegin(), diag::warn_sometimes_uninit_var)
<< VD->getDeclName() << IsCapturedByBlock << DiagKind
<< Str << I->Output << Range;
S.Diag(User->getLocStart(), diag::note_uninit_var_use)
<< IsCapturedByBlock << User->getSourceRange();
if (RemoveDiagKind != -1)
S.Diag(Fixit1.RemoveRange.getBegin(), diag::note_uninit_fixit_remove_cond)
<< RemoveDiagKind << Str << I->Output << Fixit1 << Fixit2;
Diagnosed = true;
}
if (!Diagnosed)
S.Diag(Use.getUser()->getLocStart(), diag::warn_maybe_uninit_var)
<< VD->getDeclName() << IsCapturedByBlock
<< Use.getUser()->getSourceRange();
}
/// DiagnoseUninitializedUse -- Helper function for diagnosing uses of an
/// uninitialized variable. This manages the different forms of diagnostic
/// emitted for particular types of uses. Returns true if the use was diagnosed
/// as a warning. If a particular use is one we omit warnings for, returns
/// false.
static bool DiagnoseUninitializedUse(Sema &S, const VarDecl *VD,
const UninitUse &Use,
bool alwaysReportSelfInit = false) {
if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Use.getUser())) {
// Inspect the initializer of the variable declaration which is
// being referenced prior to its initialization. We emit
// specialized diagnostics for self-initialization, and we
// specifically avoid warning about self references which take the
// form of:
//
// int x = x;
//
// This is used to indicate to GCC that 'x' is intentionally left
// uninitialized. Proven code paths which access 'x' in
// an uninitialized state after this will still warn.
if (const Expr *Initializer = VD->getInit()) {
if (!alwaysReportSelfInit && DRE == Initializer->IgnoreParenImpCasts())
return false;
ContainsReference CR(S.Context, DRE);
CR.Visit(Initializer);
if (CR.doesContainReference()) {
S.Diag(DRE->getLocStart(),
diag::warn_uninit_self_reference_in_init)
<< VD->getDeclName() << VD->getLocation() << DRE->getSourceRange();
return true;
}
}
DiagUninitUse(S, VD, Use, false);
} else {
const BlockExpr *BE = cast<BlockExpr>(Use.getUser());
if (VD->getType()->isBlockPointerType() && !VD->hasAttr<BlocksAttr>())
S.Diag(BE->getLocStart(),
diag::warn_uninit_byref_blockvar_captured_by_block)
<< VD->getDeclName();
else
DiagUninitUse(S, VD, Use, true);
}
// Report where the variable was declared when the use wasn't within
// the initializer of that declaration & we didn't already suggest
// an initialization fixit.
if (!SuggestInitializationFixit(S, VD))
S.Diag(VD->getLocStart(), diag::note_var_declared_here)
<< VD->getDeclName();
return true;
}
namespace {
class FallthroughMapper : public RecursiveASTVisitor<FallthroughMapper> {
public:
FallthroughMapper(Sema &S)
: FoundSwitchStatements(false),
S(S) {
}
bool foundSwitchStatements() const { return FoundSwitchStatements; }
void markFallthroughVisited(const AttributedStmt *Stmt) {
bool Found = FallthroughStmts.erase(Stmt);
assert(Found);
(void)Found;
}
typedef llvm::SmallPtrSet<const AttributedStmt*, 8> AttrStmts;
const AttrStmts &getFallthroughStmts() const {
return FallthroughStmts;
}
void fillReachableBlocks(CFG *Cfg) {
assert(ReachableBlocks.empty() && "ReachableBlocks already filled");
std::deque<const CFGBlock *> BlockQueue;
ReachableBlocks.insert(&Cfg->getEntry());
BlockQueue.push_back(&Cfg->getEntry());
// Mark all case blocks reachable to avoid problems with switching on
// constants, covered enums, etc.
// These blocks can contain fall-through annotations, and we don't want to
// issue a warn_fallthrough_attr_unreachable for them.
for (const auto *B : *Cfg) {
const Stmt *L = B->getLabel();
if (L && isa<SwitchCase>(L) && ReachableBlocks.insert(B).second)
BlockQueue.push_back(B);
}
while (!BlockQueue.empty()) {
const CFGBlock *P = BlockQueue.front();
BlockQueue.pop_front();
for (CFGBlock::const_succ_iterator I = P->succ_begin(),
E = P->succ_end();
I != E; ++I) {
if (*I && ReachableBlocks.insert(*I).second)
BlockQueue.push_back(*I);
}
}
}
bool checkFallThroughIntoBlock(const CFGBlock &B, int &AnnotatedCnt,
bool IsTemplateInstantiation) {
assert(!ReachableBlocks.empty() && "ReachableBlocks empty");
int UnannotatedCnt = 0;
AnnotatedCnt = 0;
std::deque<const CFGBlock*> BlockQueue(B.pred_begin(), B.pred_end());
while (!BlockQueue.empty()) {
const CFGBlock *P = BlockQueue.front();
BlockQueue.pop_front();
if (!P) continue;
const Stmt *Term = P->getTerminator();
if (Term && isa<SwitchStmt>(Term))
continue; // Switch statement, good.
const SwitchCase *SW = dyn_cast_or_null<SwitchCase>(P->getLabel());
if (SW && SW->getSubStmt() == B.getLabel() && P->begin() == P->end())
continue; // Previous case label has no statements, good.
const LabelStmt *L = dyn_cast_or_null<LabelStmt>(P->getLabel());
if (L && L->getSubStmt() == B.getLabel() && P->begin() == P->end())
continue; // Case label is preceded with a normal label, good.
if (!ReachableBlocks.count(P)) {
for (CFGBlock::const_reverse_iterator ElemIt = P->rbegin(),
ElemEnd = P->rend();
ElemIt != ElemEnd; ++ElemIt) {
if (Optional<CFGStmt> CS = ElemIt->getAs<CFGStmt>()) {
if (const AttributedStmt *AS = asFallThroughAttr(CS->getStmt())) {
// Don't issue a warning for an unreachable fallthrough
// attribute in template instantiations as it may not be
// unreachable in all instantiations of the template.
if (!IsTemplateInstantiation)
S.Diag(AS->getLocStart(),
diag::warn_fallthrough_attr_unreachable);
markFallthroughVisited(AS);
++AnnotatedCnt;
break;
}
// Don't care about other unreachable statements.
}
}
// If there are no unreachable statements, this may be a special
// case in CFG:
// case X: {
// A a; // A has a destructor.
// break;
// }
// // <<<< This place is represented by a 'hanging' CFG block.
// case Y:
continue;
}
const Stmt *LastStmt = getLastStmt(*P);
if (const AttributedStmt *AS = asFallThroughAttr(LastStmt)) {
markFallthroughVisited(AS);
++AnnotatedCnt;
continue; // Fallthrough annotation, good.
}
if (!LastStmt) { // This block contains no executable statements.
// Traverse its predecessors.
std::copy(P->pred_begin(), P->pred_end(),
std::back_inserter(BlockQueue));
continue;
}
++UnannotatedCnt;
}
return !!UnannotatedCnt;
}
// RecursiveASTVisitor setup.
bool shouldWalkTypesOfTypeLocs() const { return false; }
bool VisitAttributedStmt(AttributedStmt *S) {
if (asFallThroughAttr(S))
FallthroughStmts.insert(S);
return true;
}
bool VisitSwitchStmt(SwitchStmt *S) {
FoundSwitchStatements = true;
return true;
}
// We don't want to traverse local type declarations. We analyze their
// methods separately.
bool TraverseDecl(Decl *D) { return true; }
// We analyze lambda bodies separately. Skip them here.
bool TraverseLambdaBody(LambdaExpr *LE) { return true; }
private:
static const AttributedStmt *asFallThroughAttr(const Stmt *S) {
if (const AttributedStmt *AS = dyn_cast_or_null<AttributedStmt>(S)) {
if (hasSpecificAttr<FallThroughAttr>(AS->getAttrs()))
return AS;
}
return nullptr;
}
static const Stmt *getLastStmt(const CFGBlock &B) {
if (const Stmt *Term = B.getTerminator())
return Term;
for (CFGBlock::const_reverse_iterator ElemIt = B.rbegin(),
ElemEnd = B.rend();
ElemIt != ElemEnd; ++ElemIt) {
if (Optional<CFGStmt> CS = ElemIt->getAs<CFGStmt>())
return CS->getStmt();
}
// Workaround to detect a statement thrown out by CFGBuilder:
// case X: {} case Y:
// case X: ; case Y:
if (const SwitchCase *SW = dyn_cast_or_null<SwitchCase>(B.getLabel()))
if (!isa<SwitchCase>(SW->getSubStmt()))
return SW->getSubStmt();
return nullptr;
}
bool FoundSwitchStatements;
AttrStmts FallthroughStmts;
Sema &S;
llvm::SmallPtrSet<const CFGBlock *, 16> ReachableBlocks;
};
} // anonymous namespace
static StringRef getFallthroughAttrSpelling(Preprocessor &PP,
SourceLocation Loc) {
TokenValue FallthroughTokens[] = {
tok::l_square, tok::l_square,
PP.getIdentifierInfo("fallthrough"),
tok::r_square, tok::r_square
};
TokenValue ClangFallthroughTokens[] = {
tok::l_square, tok::l_square, PP.getIdentifierInfo("clang"),
tok::coloncolon, PP.getIdentifierInfo("fallthrough"),
tok::r_square, tok::r_square
};
bool PreferClangAttr = !PP.getLangOpts().CPlusPlus17;
StringRef MacroName;
if (PreferClangAttr)
MacroName = PP.getLastMacroWithSpelling(Loc, ClangFallthroughTokens);
if (MacroName.empty())
MacroName = PP.getLastMacroWithSpelling(Loc, FallthroughTokens);
if (MacroName.empty() && !PreferClangAttr)
MacroName = PP.getLastMacroWithSpelling(Loc, ClangFallthroughTokens);
if (MacroName.empty())
MacroName = PreferClangAttr ? "[[clang::fallthrough]]" : "[[fallthrough]]";
return MacroName;
}
static void DiagnoseSwitchLabelsFallthrough(Sema &S, AnalysisDeclContext &AC,
bool PerFunction) {
// Only perform this analysis when using [[]] attributes. There is no good
// workflow for this warning when not using C++11. There is no good way to
// silence the warning (no attribute is available) unless we are using
// [[]] attributes. One could use pragmas to silence the warning, but as a
// general solution that is gross and not in the spirit of this warning.
//
// NOTE: This an intermediate solution. There are on-going discussions on
// how to properly support this warning outside of C++11 with an annotation.
if (!AC.getASTContext().getLangOpts().DoubleSquareBracketAttributes)
return;
FallthroughMapper FM(S);
FM.TraverseStmt(AC.getBody());
if (!FM.foundSwitchStatements())
return;
if (PerFunction && FM.getFallthroughStmts().empty())
return;
CFG *Cfg = AC.getCFG();
if (!Cfg)
return;
FM.fillReachableBlocks(Cfg);
for (const CFGBlock *B : llvm::reverse(*Cfg)) {
const Stmt *Label = B->getLabel();
if (!Label || !isa<SwitchCase>(Label))
continue;
int AnnotatedCnt;
bool IsTemplateInstantiation = false;
if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(AC.getDecl()))
IsTemplateInstantiation = Function->isTemplateInstantiation();
if (!FM.checkFallThroughIntoBlock(*B, AnnotatedCnt,
IsTemplateInstantiation))
continue;
S.Diag(Label->getLocStart(),
PerFunction ? diag::warn_unannotated_fallthrough_per_function
: diag::warn_unannotated_fallthrough);
if (!AnnotatedCnt) {
SourceLocation L = Label->getLocStart();
if (L.isMacroID())
continue;
if (S.getLangOpts().CPlusPlus11) {
const Stmt *Term = B->getTerminator();
// Skip empty cases.
while (B->empty() && !Term && B->succ_size() == 1) {
B = *B->succ_begin();
Term = B->getTerminator();
}
if (!(B->empty() && Term && isa<BreakStmt>(Term))) {
Preprocessor &PP = S.getPreprocessor();
StringRef AnnotationSpelling = getFallthroughAttrSpelling(PP, L);
SmallString<64> TextToInsert(AnnotationSpelling);
TextToInsert += "; ";
S.Diag(L, diag::note_insert_fallthrough_fixit) <<
AnnotationSpelling <<
FixItHint::CreateInsertion(L, TextToInsert);
}
}
S.Diag(L, diag::note_insert_break_fixit) <<
FixItHint::CreateInsertion(L, "break; ");
}
}
for (const auto *F : FM.getFallthroughStmts())
S.Diag(F->getLocStart(), diag::err_fallthrough_attr_invalid_placement);
}
static bool isInLoop(const ASTContext &Ctx, const ParentMap &PM,
const Stmt *S) {
assert(S);
do {
switch (S->getStmtClass()) {
case Stmt::ForStmtClass:
case Stmt::WhileStmtClass:
case Stmt::CXXForRangeStmtClass:
case Stmt::ObjCForCollectionStmtClass:
return true;
case Stmt::DoStmtClass: {
const Expr *Cond = cast<DoStmt>(S)->getCond();
llvm::APSInt Val;
if (!Cond->EvaluateAsInt(Val, Ctx))
return true;
return Val.getBoolValue();
}
default:
break;
}
} while ((S = PM.getParent(S)));
return false;
}
static void diagnoseRepeatedUseOfWeak(Sema &S,
const sema::FunctionScopeInfo *CurFn,
const Decl *D,
const ParentMap &PM) {
typedef sema::FunctionScopeInfo::WeakObjectProfileTy WeakObjectProfileTy;
typedef sema::FunctionScopeInfo::WeakObjectUseMap WeakObjectUseMap;
typedef sema::FunctionScopeInfo::WeakUseVector WeakUseVector;
typedef std::pair<const Stmt *, WeakObjectUseMap::const_iterator>
StmtUsesPair;
ASTContext &Ctx = S.getASTContext();
const WeakObjectUseMap &WeakMap = CurFn->getWeakObjectUses();
// Extract all weak objects that are referenced more than once.
SmallVector<StmtUsesPair, 8> UsesByStmt;
for (WeakObjectUseMap::const_iterator I = WeakMap.begin(), E = WeakMap.end();
I != E; ++I) {
const WeakUseVector &Uses = I->second;
// Find the first read of the weak object.
WeakUseVector::const_iterator UI = Uses.begin(), UE = Uses.end();
for ( ; UI != UE; ++UI) {
if (UI->isUnsafe())
break;
}
// If there were only writes to this object, don't warn.
if (UI == UE)
continue;
// If there was only one read, followed by any number of writes, and the
// read is not within a loop, don't warn. Additionally, don't warn in a
// loop if the base object is a local variable -- local variables are often
// changed in loops.
if (UI == Uses.begin()) {
WeakUseVector::const_iterator UI2 = UI;
for (++UI2; UI2 != UE; ++UI2)
if (UI2->isUnsafe())
break;
if (UI2 == UE) {
if (!isInLoop(Ctx, PM, UI->getUseExpr()))
continue;
const WeakObjectProfileTy &Profile = I->first;
if (!Profile.isExactProfile())
continue;
const NamedDecl *Base = Profile.getBase();
if (!Base)
Base = Profile.getProperty();
assert(Base && "A profile always has a base or property.");
if (const VarDecl *BaseVar = dyn_cast<VarDecl>(Base))
if (BaseVar->hasLocalStorage() && !isa<ParmVarDecl>(Base))
continue;
}
}
UsesByStmt.push_back(StmtUsesPair(UI->getUseExpr(), I));
}
if (UsesByStmt.empty())
return;
// Sort by first use so that we emit the warnings in a deterministic order.
SourceManager &SM = S.getSourceManager();
std::sort(UsesByStmt.begin(), UsesByStmt.end(),
[&SM](const StmtUsesPair &LHS, const StmtUsesPair &RHS) {
return SM.isBeforeInTranslationUnit(LHS.first->getLocStart(),
RHS.first->getLocStart());
});
// Classify the current code body for better warning text.
// This enum should stay in sync with the cases in
// warn_arc_repeated_use_of_weak and warn_arc_possible_repeated_use_of_weak.
// FIXME: Should we use a common classification enum and the same set of
// possibilities all throughout Sema?
enum {
Function,
Method,
Block,
Lambda
} FunctionKind;
if (isa<sema::BlockScopeInfo>(CurFn))
FunctionKind = Block;
else if (isa<sema::LambdaScopeInfo>(CurFn))
FunctionKind = Lambda;
else if (isa<ObjCMethodDecl>(D))
FunctionKind = Method;
else
FunctionKind = Function;
// Iterate through the sorted problems and emit warnings for each.
for (const auto &P : UsesByStmt) {
const Stmt *FirstRead = P.first;
const WeakObjectProfileTy &Key = P.second->first;
const WeakUseVector &Uses = P.second->second;
// For complicated expressions like 'a.b.c' and 'x.b.c', WeakObjectProfileTy
// may not contain enough information to determine that these are different
// properties. We can only be 100% sure of a repeated use in certain cases,
// and we adjust the diagnostic kind accordingly so that the less certain
// case can be turned off if it is too noisy.
unsigned DiagKind;
if (Key.isExactProfile())
DiagKind = diag::warn_arc_repeated_use_of_weak;
else
DiagKind = diag::warn_arc_possible_repeated_use_of_weak;
// Classify the weak object being accessed for better warning text.
// This enum should stay in sync with the cases in
// warn_arc_repeated_use_of_weak and warn_arc_possible_repeated_use_of_weak.
enum {
Variable,
Property,
ImplicitProperty,
Ivar
} ObjectKind;
const NamedDecl *KeyProp = Key.getProperty();
if (isa<VarDecl>(KeyProp))
ObjectKind = Variable;
else if (isa<ObjCPropertyDecl>(KeyProp))
ObjectKind = Property;
else if (isa<ObjCMethodDecl>(KeyProp))
ObjectKind = ImplicitProperty;
else if (isa<ObjCIvarDecl>(KeyProp))
ObjectKind = Ivar;
else
llvm_unreachable("Unexpected weak object kind!");
// Do not warn about IBOutlet weak property receivers being set to null
// since they are typically only used from the main thread.
if (const ObjCPropertyDecl *Prop = dyn_cast<ObjCPropertyDecl>(KeyProp))
if (Prop->hasAttr<IBOutletAttr>())
continue;
// Show the first time the object was read.
S.Diag(FirstRead->getLocStart(), DiagKind)
<< int(ObjectKind) << KeyProp << int(FunctionKind)
<< FirstRead->getSourceRange();
// Print all the other accesses as notes.
for (const auto &Use : Uses) {
if (Use.getUseExpr() == FirstRead)
continue;
S.Diag(Use.getUseExpr()->getLocStart(),
diag::note_arc_weak_also_accessed_here)
<< Use.getUseExpr()->getSourceRange();
}
}
}
namespace {
class UninitValsDiagReporter : public UninitVariablesHandler {
Sema &S;
typedef SmallVector<UninitUse, 2> UsesVec;
typedef llvm::PointerIntPair<UsesVec *, 1, bool> MappedType;
// Prefer using MapVector to DenseMap, so that iteration order will be
// the same as insertion order. This is needed to obtain a deterministic
// order of diagnostics when calling flushDiagnostics().
typedef llvm::MapVector<const VarDecl *, MappedType> UsesMap;
UsesMap uses;
public:
UninitValsDiagReporter(Sema &S) : S(S) {}
~UninitValsDiagReporter() override { flushDiagnostics(); }
MappedType &getUses(const VarDecl *vd) {
MappedType &V = uses[vd];
if (!V.getPointer())
V.setPointer(new UsesVec());
return V;
}
void handleUseOfUninitVariable(const VarDecl *vd,
const UninitUse &use) override {
getUses(vd).getPointer()->push_back(use);
}
void handleSelfInit(const VarDecl *vd) override {
getUses(vd).setInt(true);
}
void flushDiagnostics() {
for (const auto &P : uses) {
const VarDecl *vd = P.first;
const MappedType &V = P.second;
UsesVec *vec = V.getPointer();
bool hasSelfInit = V.getInt();
// Specially handle the case where we have uses of an uninitialized
// variable, but the root cause is an idiomatic self-init. We want
// to report the diagnostic at the self-init since that is the root cause.
if (!vec->empty() && hasSelfInit && hasAlwaysUninitializedUse(vec))
DiagnoseUninitializedUse(S, vd,
UninitUse(vd->getInit()->IgnoreParenCasts(),
/* isAlwaysUninit */ true),
/* alwaysReportSelfInit */ true);
else {
// Sort the uses by their SourceLocations. While not strictly
// guaranteed to produce them in line/column order, this will provide
// a stable ordering.
std::sort(vec->begin(), vec->end(),
[](const UninitUse &a, const UninitUse &b) {
// Prefer a more confident report over a less confident one.
if (a.getKind() != b.getKind())
return a.getKind() > b.getKind();
return a.getUser()->getLocStart() < b.getUser()->getLocStart();
});
for (const auto &U : *vec) {
// If we have self-init, downgrade all uses to 'may be uninitialized'.
UninitUse Use = hasSelfInit ? UninitUse(U.getUser(), false) : U;
if (DiagnoseUninitializedUse(S, vd, Use))
// Skip further diagnostics for this variable. We try to warn only
// on the first point at which a variable is used uninitialized.
break;
}
}
// Release the uses vector.
delete vec;
}
uses.clear();
}
private:
static bool hasAlwaysUninitializedUse(const UsesVec* vec) {
return std::any_of(vec->begin(), vec->end(), [](const UninitUse &U) {
return U.getKind() == UninitUse::Always ||
U.getKind() == UninitUse::AfterCall ||
U.getKind() == UninitUse::AfterDecl;
});
}
};
} // anonymous namespace
namespace clang {
namespace {
typedef SmallVector<PartialDiagnosticAt, 1> OptionalNotes;
typedef std::pair<PartialDiagnosticAt, OptionalNotes> DelayedDiag;
typedef std::list<DelayedDiag> DiagList;
struct SortDiagBySourceLocation {
SourceManager &SM;
SortDiagBySourceLocation(SourceManager &SM) : SM(SM) {}
bool operator()(const DelayedDiag &left, const DelayedDiag &right) {
// Although this call will be slow, this is only called when outputting
// multiple warnings.
return SM.isBeforeInTranslationUnit(left.first.first, right.first.first);
}
};
} // anonymous namespace
} // namespace clang
//===----------------------------------------------------------------------===//
// -Wthread-safety
//===----------------------------------------------------------------------===//
namespace clang {
namespace threadSafety {
namespace {
class ThreadSafetyReporter : public clang::threadSafety::ThreadSafetyHandler {
Sema &S;
DiagList Warnings;
SourceLocation FunLocation, FunEndLocation;
const FunctionDecl *CurrentFunction;
bool Verbose;
OptionalNotes getNotes() const {
if (Verbose && CurrentFunction) {
PartialDiagnosticAt FNote(CurrentFunction->getBody()->getLocStart(),
S.PDiag(diag::note_thread_warning_in_fun)
<< CurrentFunction->getNameAsString());
return OptionalNotes(1, FNote);
}
return OptionalNotes();
}
OptionalNotes getNotes(const PartialDiagnosticAt &Note) const {
OptionalNotes ONS(1, Note);
if (Verbose && CurrentFunction) {
PartialDiagnosticAt FNote(CurrentFunction->getBody()->getLocStart(),
S.PDiag(diag::note_thread_warning_in_fun)
<< CurrentFunction->getNameAsString());
ONS.push_back(std::move(FNote));
}
return ONS;
}
OptionalNotes getNotes(const PartialDiagnosticAt &Note1,
const PartialDiagnosticAt &Note2) const {
OptionalNotes ONS;
ONS.push_back(Note1);
ONS.push_back(Note2);
if (Verbose && CurrentFunction) {
PartialDiagnosticAt FNote(CurrentFunction->getBody()->getLocStart(),
S.PDiag(diag::note_thread_warning_in_fun)
<< CurrentFunction->getNameAsString());
ONS.push_back(std::move(FNote));
}
return ONS;
}
// Helper functions
void warnLockMismatch(unsigned DiagID, StringRef Kind, Name LockName,
SourceLocation Loc) {
// Gracefully handle rare cases when the analysis can't get a more
// precise source location.
if (!Loc.isValid())
Loc = FunLocation;
PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID) << Kind << LockName);
Warnings.emplace_back(std::move(Warning), getNotes());
}
public:
ThreadSafetyReporter(Sema &S, SourceLocation FL, SourceLocation FEL)
: S(S), FunLocation(FL), FunEndLocation(FEL),
CurrentFunction(nullptr), Verbose(false) {}
void setVerbose(bool b) { Verbose = b; }
/// \brief Emit all buffered diagnostics in order of sourcelocation.
/// We need to output diagnostics produced while iterating through
/// the lockset in deterministic order, so this function orders diagnostics
/// and outputs them.
void emitDiagnostics() {
Warnings.sort(SortDiagBySourceLocation(S.getSourceManager()));
for (const auto &Diag : Warnings) {
S.Diag(Diag.first.first, Diag.first.second);
for (const auto &Note : Diag.second)
S.Diag(Note.first, Note.second);
}
}
void handleInvalidLockExp(StringRef Kind, SourceLocation Loc) override {
PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_cannot_resolve_lock)
<< Loc);
Warnings.emplace_back(std::move(Warning), getNotes());
}
void handleUnmatchedUnlock(StringRef Kind, Name LockName,
SourceLocation Loc) override {
warnLockMismatch(diag::warn_unlock_but_no_lock, Kind, LockName, Loc);
}
void handleIncorrectUnlockKind(StringRef Kind, Name LockName,
LockKind Expected, LockKind Received,
SourceLocation Loc) override {
if (Loc.isInvalid())
Loc = FunLocation;
PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_unlock_kind_mismatch)
<< Kind << LockName << Received
<< Expected);
Warnings.emplace_back(std::move(Warning), getNotes());
}
void handleDoubleLock(StringRef Kind, Name LockName, SourceLocation Loc) override {
warnLockMismatch(diag::warn_double_lock, Kind, LockName, Loc);
}
void handleMutexHeldEndOfScope(StringRef Kind, Name LockName,
SourceLocation LocLocked,
SourceLocation LocEndOfScope,
LockErrorKind LEK) override {
unsigned DiagID = 0;
switch (LEK) {
case LEK_LockedSomePredecessors:
DiagID = diag::warn_lock_some_predecessors;
break;
case LEK_LockedSomeLoopIterations:
DiagID = diag::warn_expecting_lock_held_on_loop;
break;
case LEK_LockedAtEndOfFunction:
DiagID = diag::warn_no_unlock;
break;
case LEK_NotLockedAtEndOfFunction:
DiagID = diag::warn_expecting_locked;
break;
}
if (LocEndOfScope.isInvalid())
LocEndOfScope = FunEndLocation;
PartialDiagnosticAt Warning(LocEndOfScope, S.PDiag(DiagID) << Kind
<< LockName);
if (LocLocked.isValid()) {
PartialDiagnosticAt Note(LocLocked, S.PDiag(diag::note_locked_here)
<< Kind);
Warnings.emplace_back(std::move(Warning), getNotes(Note));
return;
}
Warnings.emplace_back(std::move(Warning), getNotes());
}
void handleExclusiveAndShared(StringRef Kind, Name LockName,
SourceLocation Loc1,
SourceLocation Loc2) override {
PartialDiagnosticAt Warning(Loc1,
S.PDiag(diag::warn_lock_exclusive_and_shared)
<< Kind << LockName);
PartialDiagnosticAt Note(Loc2, S.PDiag(diag::note_lock_exclusive_and_shared)
<< Kind << LockName);
Warnings.emplace_back(std::move(Warning), getNotes(Note));
}
void handleNoMutexHeld(StringRef Kind, const NamedDecl *D,
ProtectedOperationKind POK, AccessKind AK,
SourceLocation Loc) override {
assert((POK == POK_VarAccess || POK == POK_VarDereference) &&
"Only works for variables");
unsigned DiagID = POK == POK_VarAccess?
diag::warn_variable_requires_any_lock:
diag::warn_var_deref_requires_any_lock;
PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID)
<< D->getNameAsString() << getLockKindFromAccessKind(AK));
Warnings.emplace_back(std::move(Warning), getNotes());
}
void handleMutexNotHeld(StringRef Kind, const NamedDecl *D,
ProtectedOperationKind POK, Name LockName,
LockKind LK, SourceLocation Loc,
Name *PossibleMatch) override {
unsigned DiagID = 0;
if (PossibleMatch) {
switch (POK) {
case POK_VarAccess:
DiagID = diag::warn_variable_requires_lock_precise;
break;
case POK_VarDereference:
DiagID = diag::warn_var_deref_requires_lock_precise;
break;
case POK_FunctionCall:
DiagID = diag::warn_fun_requires_lock_precise;
break;
case POK_PassByRef:
DiagID = diag::warn_guarded_pass_by_reference;
break;
case POK_PtPassByRef:
DiagID = diag::warn_pt_guarded_pass_by_reference;
break;
}
PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID) << Kind
<< D->getNameAsString()
<< LockName << LK);
PartialDiagnosticAt Note(Loc, S.PDiag(diag::note_found_mutex_near_match)
<< *PossibleMatch);
if (Verbose && POK == POK_VarAccess) {
PartialDiagnosticAt VNote(D->getLocation(),
S.PDiag(diag::note_guarded_by_declared_here)
<< D->getNameAsString());
Warnings.emplace_back(std::move(Warning), getNotes(Note, VNote));
} else
Warnings.emplace_back(std::move(Warning), getNotes(Note));
} else {
switch (POK) {
case POK_VarAccess:
DiagID = diag::warn_variable_requires_lock;
break;
case POK_VarDereference:
DiagID = diag::warn_var_deref_requires_lock;
break;
case POK_FunctionCall:
DiagID = diag::warn_fun_requires_lock;
break;
case POK_PassByRef:
DiagID = diag::warn_guarded_pass_by_reference;
break;
case POK_PtPassByRef:
DiagID = diag::warn_pt_guarded_pass_by_reference;
break;
}
PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID) << Kind
<< D->getNameAsString()
<< LockName << LK);
if (Verbose && POK == POK_VarAccess) {
PartialDiagnosticAt Note(D->getLocation(),
S.PDiag(diag::note_guarded_by_declared_here)
<< D->getNameAsString());
Warnings.emplace_back(std::move(Warning), getNotes(Note));
} else
Warnings.emplace_back(std::move(Warning), getNotes());
}
}
void handleNegativeNotHeld(StringRef Kind, Name LockName, Name Neg,
SourceLocation Loc) override {
PartialDiagnosticAt Warning(Loc,
S.PDiag(diag::warn_acquire_requires_negative_cap)
<< Kind << LockName << Neg);
Warnings.emplace_back(std::move(Warning), getNotes());
}
void handleFunExcludesLock(StringRef Kind, Name FunName, Name LockName,
SourceLocation Loc) override {
PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_fun_excludes_mutex)
<< Kind << FunName << LockName);
Warnings.emplace_back(std::move(Warning), getNotes());
}
void handleLockAcquiredBefore(StringRef Kind, Name L1Name, Name L2Name,
SourceLocation Loc) override {
PartialDiagnosticAt Warning(Loc,
S.PDiag(diag::warn_acquired_before) << Kind << L1Name << L2Name);
Warnings.emplace_back(std::move(Warning), getNotes());
}
void handleBeforeAfterCycle(Name L1Name, SourceLocation Loc) override {
PartialDiagnosticAt Warning(Loc,
S.PDiag(diag::warn_acquired_before_after_cycle) << L1Name);
Warnings.emplace_back(std::move(Warning), getNotes());
}
void enterFunction(const FunctionDecl* FD) override {
CurrentFunction = FD;
}
void leaveFunction(const FunctionDecl* FD) override {
CurrentFunction = nullptr;
}
};
} // anonymous namespace
} // namespace threadSafety
} // namespace clang
//===----------------------------------------------------------------------===//
// -Wconsumed
//===----------------------------------------------------------------------===//
namespace clang {
namespace consumed {
namespace {
class ConsumedWarningsHandler : public ConsumedWarningsHandlerBase {
Sema &S;
DiagList Warnings;
public:
ConsumedWarningsHandler(Sema &S) : S(S) {}
void emitDiagnostics() override {
Warnings.sort(SortDiagBySourceLocation(S.getSourceManager()));
for (const auto &Diag : Warnings) {
S.Diag(Diag.first.first, Diag.first.second);
for (const auto &Note : Diag.second)
S.Diag(Note.first, Note.second);
}
}
void warnLoopStateMismatch(SourceLocation Loc,
StringRef VariableName) override {
PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_loop_state_mismatch) <<
VariableName);
Warnings.emplace_back(std::move(Warning), OptionalNotes());
}
void warnParamReturnTypestateMismatch(SourceLocation Loc,
StringRef VariableName,
StringRef ExpectedState,
StringRef ObservedState) override {
PartialDiagnosticAt Warning(Loc, S.PDiag(
diag::warn_param_return_typestate_mismatch) << VariableName <<
ExpectedState << ObservedState);
Warnings.emplace_back(std::move(Warning), OptionalNotes());
}
void warnParamTypestateMismatch(SourceLocation Loc, StringRef ExpectedState,
StringRef ObservedState) override {
PartialDiagnosticAt Warning(Loc, S.PDiag(
diag::warn_param_typestate_mismatch) << ExpectedState << ObservedState);
Warnings.emplace_back(std::move(Warning), OptionalNotes());
}
void warnReturnTypestateForUnconsumableType(SourceLocation Loc,
StringRef TypeName) override {
PartialDiagnosticAt Warning(Loc, S.PDiag(
diag::warn_return_typestate_for_unconsumable_type) << TypeName);
Warnings.emplace_back(std::move(Warning), OptionalNotes());
}
void warnReturnTypestateMismatch(SourceLocation Loc, StringRef ExpectedState,
StringRef ObservedState) override {
PartialDiagnosticAt Warning(Loc, S.PDiag(
diag::warn_return_typestate_mismatch) << ExpectedState << ObservedState);
Warnings.emplace_back(std::move(Warning), OptionalNotes());
}
void warnUseOfTempInInvalidState(StringRef MethodName, StringRef State,
SourceLocation Loc) override {
PartialDiagnosticAt Warning(Loc, S.PDiag(
diag::warn_use_of_temp_in_invalid_state) << MethodName << State);
Warnings.emplace_back(std::move(Warning), OptionalNotes());
}
void warnUseInInvalidState(StringRef MethodName, StringRef VariableName,
StringRef State, SourceLocation Loc) override {
PartialDiagnosticAt Warning(Loc, S.PDiag(diag::warn_use_in_invalid_state) <<
MethodName << VariableName << State);
Warnings.emplace_back(std::move(Warning), OptionalNotes());
}
};
} // anonymous namespace
} // namespace consumed
} // namespace clang
//===----------------------------------------------------------------------===//
// AnalysisBasedWarnings - Worker object used by Sema to execute analysis-based
// warnings on a function, method, or block.
//===----------------------------------------------------------------------===//
clang::sema::AnalysisBasedWarnings::Policy::Policy() {
enableCheckFallThrough = 1;
enableCheckUnreachable = 0;
enableThreadSafetyAnalysis = 0;
enableConsumedAnalysis = 0;
}
static unsigned isEnabled(DiagnosticsEngine &D, unsigned diag) {
return (unsigned)!D.isIgnored(diag, SourceLocation());
}
clang::sema::AnalysisBasedWarnings::AnalysisBasedWarnings(Sema &s)
: S(s),
NumFunctionsAnalyzed(0),
NumFunctionsWithBadCFGs(0),
NumCFGBlocks(0),
MaxCFGBlocksPerFunction(0),
NumUninitAnalysisFunctions(0),
NumUninitAnalysisVariables(0),
MaxUninitAnalysisVariablesPerFunction(0),
NumUninitAnalysisBlockVisits(0),
MaxUninitAnalysisBlockVisitsPerFunction(0) {
using namespace diag;
DiagnosticsEngine &D = S.getDiagnostics();
DefaultPolicy.enableCheckUnreachable =
isEnabled(D, warn_unreachable) ||
isEnabled(D, warn_unreachable_break) ||
isEnabled(D, warn_unreachable_return) ||
isEnabled(D, warn_unreachable_loop_increment);
DefaultPolicy.enableThreadSafetyAnalysis =
isEnabled(D, warn_double_lock);
DefaultPolicy.enableConsumedAnalysis =
isEnabled(D, warn_use_in_invalid_state);
}
static void flushDiagnostics(Sema &S, const sema::FunctionScopeInfo *fscope) {
for (const auto &D : fscope->PossiblyUnreachableDiags)
S.Diag(D.Loc, D.PD);
}
void clang::sema::
AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
sema::FunctionScopeInfo *fscope,
const Decl *D, const BlockExpr *blkExpr) {
// We avoid doing analysis-based warnings when there are errors for
// two reasons:
// (1) The CFGs often can't be constructed (if the body is invalid), so
// don't bother trying.
// (2) The code already has problems; running the analysis just takes more
// time.
DiagnosticsEngine &Diags = S.getDiagnostics();
// Do not do any analysis if we are going to just ignore them.
if (Diags.getIgnoreAllWarnings() ||
(Diags.getSuppressSystemWarnings() &&
S.SourceMgr.isInSystemHeader(D->getLocation())))
return;
// For code in dependent contexts, we'll do this at instantiation time.
if (cast<DeclContext>(D)->isDependentContext())
return;
if (Diags.hasUncompilableErrorOccurred()) {
// Flush out any possibly unreachable diagnostics.
flushDiagnostics(S, fscope);
return;
}
const Stmt *Body = D->getBody();
assert(Body);
// Construct the analysis context with the specified CFG build options.
AnalysisDeclContext AC(/* AnalysisDeclContextManager */ nullptr, D);
// Don't generate EH edges for CallExprs as we'd like to avoid the n^2
// explosion for destructors that can result and the compile time hit.
AC.getCFGBuildOptions().PruneTriviallyFalseEdges = true;
AC.getCFGBuildOptions().AddEHEdges = false;
AC.getCFGBuildOptions().AddInitializers = true;
AC.getCFGBuildOptions().AddImplicitDtors = true;
AC.getCFGBuildOptions().AddTemporaryDtors = true;
AC.getCFGBuildOptions().AddCXXNewAllocator = false;
AC.getCFGBuildOptions().AddCXXDefaultInitExprInCtors = true;
// Force that certain expressions appear as CFGElements in the CFG. This
// is used to speed up various analyses.
// FIXME: This isn't the right factoring. This is here for initial
// prototyping, but we need a way for analyses to say what expressions they
// expect to always be CFGElements and then fill in the BuildOptions
// appropriately. This is essentially a layering violation.
if (P.enableCheckUnreachable || P.enableThreadSafetyAnalysis ||
P.enableConsumedAnalysis) {
// Unreachable code analysis and thread safety require a linearized CFG.
AC.getCFGBuildOptions().setAllAlwaysAdd();
}
else {
AC.getCFGBuildOptions()
.setAlwaysAdd(Stmt::BinaryOperatorClass)
.setAlwaysAdd(Stmt::CompoundAssignOperatorClass)
.setAlwaysAdd(Stmt::BlockExprClass)
.setAlwaysAdd(Stmt::CStyleCastExprClass)
.setAlwaysAdd(Stmt::DeclRefExprClass)
.setAlwaysAdd(Stmt::ImplicitCastExprClass)
.setAlwaysAdd(Stmt::UnaryOperatorClass)
.setAlwaysAdd(Stmt::AttributedStmtClass);
}
// Install the logical handler for -Wtautological-overlap-compare
std::unique_ptr<LogicalErrorHandler> LEH;
if (!Diags.isIgnored(diag::warn_tautological_overlap_comparison,
D->getLocStart())) {
LEH.reset(new LogicalErrorHandler(S));
AC.getCFGBuildOptions().Observer = LEH.get();
}
// Emit delayed diagnostics.
if (!fscope->PossiblyUnreachableDiags.empty()) {
bool analyzed = false;
// Register the expressions with the CFGBuilder.
for (const auto &D : fscope->PossiblyUnreachableDiags) {
if (D.stmt)
AC.registerForcedBlockExpression(D.stmt);
}
if (AC.getCFG()) {
analyzed = true;
for (const auto &D : fscope->PossiblyUnreachableDiags) {
bool processed = false;
if (D.stmt) {
const CFGBlock *block = AC.getBlockForRegisteredExpression(D.stmt);
CFGReverseBlockReachabilityAnalysis *cra =
AC.getCFGReachablityAnalysis();
// FIXME: We should be able to assert that block is non-null, but
// the CFG analysis can skip potentially-evaluated expressions in
// edge cases; see test/Sema/vla-2.c.
if (block && cra) {
// Can this block be reached from the entrance?
if (cra->isReachable(&AC.getCFG()->getEntry(), block))
S.Diag(D.Loc, D.PD);
processed = true;
}
}
if (!processed) {
// Emit the warning anyway if we cannot map to a basic block.
S.Diag(D.Loc, D.PD);
}
}
}
if (!analyzed)
flushDiagnostics(S, fscope);
}
// Warning: check missing 'return'
if (P.enableCheckFallThrough) {
const CheckFallThroughDiagnostics &CD =
(isa<BlockDecl>(D)
? CheckFallThroughDiagnostics::MakeForBlock()
: (isa<CXXMethodDecl>(D) &&
cast<CXXMethodDecl>(D)->getOverloadedOperator() == OO_Call &&
cast<CXXMethodDecl>(D)->getParent()->isLambda())
? CheckFallThroughDiagnostics::MakeForLambda()
: (fscope->isCoroutine()
? CheckFallThroughDiagnostics::MakeForCoroutine(D)
: CheckFallThroughDiagnostics::MakeForFunction(D)));
CheckFallThroughForBody(S, D, Body, blkExpr, CD, AC);
}
// Warning: check for unreachable code
if (P.enableCheckUnreachable) {
// Only check for unreachable code on non-template instantiations.
// Different template instantiations can effectively change the control-flow
// and it is very difficult to prove that a snippet of code in a template
// is unreachable for all instantiations.
bool isTemplateInstantiation = false;
if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(D))
isTemplateInstantiation = Function->isTemplateInstantiation();
if (!isTemplateInstantiation)
CheckUnreachable(S, AC);
}
// Check for thread safety violations
if (P.enableThreadSafetyAnalysis) {
SourceLocation FL = AC.getDecl()->getLocation();
SourceLocation FEL = AC.getDecl()->getLocEnd();
threadSafety::ThreadSafetyReporter Reporter(S, FL, FEL);
if (!Diags.isIgnored(diag::warn_thread_safety_beta, D->getLocStart()))
Reporter.setIssueBetaWarnings(true);
if (!Diags.isIgnored(diag::warn_thread_safety_verbose, D->getLocStart()))
Reporter.setVerbose(true);
threadSafety::runThreadSafetyAnalysis(AC, Reporter,
&S.ThreadSafetyDeclCache);
Reporter.emitDiagnostics();
}
// Check for violations of consumed properties.
if (P.enableConsumedAnalysis) {
consumed::ConsumedWarningsHandler WarningHandler(S);
consumed::ConsumedAnalyzer Analyzer(WarningHandler);
Analyzer.run(AC);
}
if (!Diags.isIgnored(diag::warn_uninit_var, D->getLocStart()) ||
!Diags.isIgnored(diag::warn_sometimes_uninit_var, D->getLocStart()) ||
!Diags.isIgnored(diag::warn_maybe_uninit_var, D->getLocStart())) {
if (CFG *cfg = AC.getCFG()) {
UninitValsDiagReporter reporter(S);
UninitVariablesAnalysisStats stats;
std::memset(&stats, 0, sizeof(UninitVariablesAnalysisStats));
runUninitializedVariablesAnalysis(*cast<DeclContext>(D), *cfg, AC,
reporter, stats);
if (S.CollectStats && stats.NumVariablesAnalyzed > 0) {
++NumUninitAnalysisFunctions;
NumUninitAnalysisVariables += stats.NumVariablesAnalyzed;
NumUninitAnalysisBlockVisits += stats.NumBlockVisits;
MaxUninitAnalysisVariablesPerFunction =
std::max(MaxUninitAnalysisVariablesPerFunction,
stats.NumVariablesAnalyzed);
MaxUninitAnalysisBlockVisitsPerFunction =
std::max(MaxUninitAnalysisBlockVisitsPerFunction,
stats.NumBlockVisits);
}
}
}
bool FallThroughDiagFull =
!Diags.isIgnored(diag::warn_unannotated_fallthrough, D->getLocStart());
bool FallThroughDiagPerFunction = !Diags.isIgnored(
diag::warn_unannotated_fallthrough_per_function, D->getLocStart());
if (FallThroughDiagFull || FallThroughDiagPerFunction ||
fscope->HasFallthroughStmt) {
DiagnoseSwitchLabelsFallthrough(S, AC, !FallThroughDiagFull);
}
if (S.getLangOpts().ObjCWeak &&
!Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, D->getLocStart()))
diagnoseRepeatedUseOfWeak(S, fscope, D, AC.getParentMap());
// Check for infinite self-recursion in functions
if (!Diags.isIgnored(diag::warn_infinite_recursive_function,
D->getLocStart())) {
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
checkRecursiveFunction(S, FD, Body, AC);
}
}
// Check for throw out of non-throwing function.
if (!Diags.isIgnored(diag::warn_throw_in_noexcept_func, D->getLocStart()))
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
if (S.getLangOpts().CPlusPlus && isNoexcept(FD))
checkThrowInNonThrowingFunc(S, FD, AC);
// If none of the previous checks caused a CFG build, trigger one here
// for -Wtautological-overlap-compare
if (!Diags.isIgnored(diag::warn_tautological_overlap_comparison,
D->getLocStart())) {
AC.getCFG();
}
// Collect statistics about the CFG if it was built.
if (S.CollectStats && AC.isCFGBuilt()) {
++NumFunctionsAnalyzed;
if (CFG *cfg = AC.getCFG()) {
// If we successfully built a CFG for this context, record some more
// detail information about it.
NumCFGBlocks += cfg->getNumBlockIDs();
MaxCFGBlocksPerFunction = std::max(MaxCFGBlocksPerFunction,
cfg->getNumBlockIDs());
} else {
++NumFunctionsWithBadCFGs;
}
}
}
void clang::sema::AnalysisBasedWarnings::PrintStats() const {
llvm::errs() << "\n*** Analysis Based Warnings Stats:\n";
unsigned NumCFGsBuilt = NumFunctionsAnalyzed - NumFunctionsWithBadCFGs;
unsigned AvgCFGBlocksPerFunction =
!NumCFGsBuilt ? 0 : NumCFGBlocks/NumCFGsBuilt;
llvm::errs() << NumFunctionsAnalyzed << " functions analyzed ("
<< NumFunctionsWithBadCFGs << " w/o CFGs).\n"
<< " " << NumCFGBlocks << " CFG blocks built.\n"
<< " " << AvgCFGBlocksPerFunction
<< " average CFG blocks per function.\n"
<< " " << MaxCFGBlocksPerFunction
<< " max CFG blocks per function.\n";
unsigned AvgUninitVariablesPerFunction = !NumUninitAnalysisFunctions ? 0
: NumUninitAnalysisVariables/NumUninitAnalysisFunctions;
unsigned AvgUninitBlockVisitsPerFunction = !NumUninitAnalysisFunctions ? 0
: NumUninitAnalysisBlockVisits/NumUninitAnalysisFunctions;
llvm::errs() << NumUninitAnalysisFunctions
<< " functions analyzed for uninitialiazed variables\n"
<< " " << NumUninitAnalysisVariables << " variables analyzed.\n"
<< " " << AvgUninitVariablesPerFunction
<< " average variables per function.\n"
<< " " << MaxUninitAnalysisVariablesPerFunction
<< " max variables per function.\n"
<< " " << NumUninitAnalysisBlockVisits << " block visits.\n"
<< " " << AvgUninitBlockVisitsPerFunction
<< " average block visits per function.\n"
<< " " << MaxUninitAnalysisBlockVisitsPerFunction
<< " max block visits per function.\n";
}
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