[Sema] Warn about memcpy'ing non-trivial C structs.

Issue a warning when non-trivial C structs are copied or initialized by
calls to memset, bzero, memcpy, or memmove.

rdar://problem/36124208

Differential Revision: https://reviews.llvm.org/D45310

llvm-svn: 330202

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -613,6 +613,13 @@ def err_function_needs_feature
             "'%2'">;
 def warn_builtin_unknown : Warning<"use of unknown builtin %0">,
   InGroup<ImplicitFunctionDeclare>, DefaultError;
+def warn_cstruct_memaccess : Warning<
+  "%select{destination for|source of|first operand of|second operand of}0 this "
+  "%1 call is a pointer to record %2 that is not trivial to "
+  "%select{primitive-default-initialize|primitive-copy}3">,
+  InGroup<DiagGroup<"nontrivial-memaccess">>;
+def note_nontrivial_field : Note<
+  "field is non-trivial to %select{copy|default-initialize}0">;
 def warn_dyn_class_memaccess : Warning<
   "%select{destination for|source of|first operand of|second operand of}0 this "
   "%1 call is a pointer to %select{|class containing a }2dynamic class %3; "

clang/lib/Sema/SemaChecking.cpp

@@ -28,6 +28,7 @@
 #include "clang/AST/ExprObjC.h"
 #include "clang/AST/ExprOpenMP.h"
 #include "clang/AST/NSAPI.h"
+#include "clang/AST/NonTrivialTypeVisitor.h"
 #include "clang/AST/OperationKinds.h"
 #include "clang/AST/Stmt.h"
 #include "clang/AST/TemplateBase.h"
@@ -7378,6 +7379,98 @@ static QualType getSizeOfArgType(const Expr *E) {
   return QualType();
 }
 
+namespace {
+
+struct SearchNonTrivialToInitializeField
+    : DefaultInitializedTypeVisitor<SearchNonTrivialToInitializeField> {
+  using Super =
+      DefaultInitializedTypeVisitor<SearchNonTrivialToInitializeField>;
+
+  SearchNonTrivialToInitializeField(const Expr *E, Sema &S) : E(E), S(S) {}
+
+  void visitWithKind(QualType::PrimitiveDefaultInitializeKind PDIK, QualType FT,
+                     SourceLocation SL) {
+    if (const auto *AT = asDerived().getContext().getAsArrayType(FT)) {
+      asDerived().visitArray(PDIK, AT, SL);
+      return;
+    }
+
+    Super::visitWithKind(PDIK, FT, SL);
+  }
+
+  void visitARCStrong(QualType FT, SourceLocation SL) {
+    S.DiagRuntimeBehavior(SL, E, S.PDiag(diag::note_nontrivial_field) << 1);
+  }
+  void visitARCWeak(QualType FT, SourceLocation SL) {
+    S.DiagRuntimeBehavior(SL, E, S.PDiag(diag::note_nontrivial_field) << 1);
+  }
+  void visitStruct(QualType FT, SourceLocation SL) {
+    for (const FieldDecl *FD : FT->castAs<RecordType>()->getDecl()->fields())
+      visit(FD->getType(), FD->getLocation());
+  }
+  void visitArray(QualType::PrimitiveDefaultInitializeKind PDIK,
+                  const ArrayType *AT, SourceLocation SL) {
+    visit(getContext().getBaseElementType(AT), SL);
+  }
+  void visitTrivial(QualType FT, SourceLocation SL) {}
+
+  static void diag(QualType RT, const Expr *E, Sema &S) {
+    SearchNonTrivialToInitializeField(E, S).visitStruct(RT, SourceLocation());
+  }
+
+  ASTContext &getContext() { return S.getASTContext(); }
+
+  const Expr *E;
+  Sema &S;
+};
+
+struct SearchNonTrivialToCopyField
+    : CopiedTypeVisitor<SearchNonTrivialToCopyField, false> {
+  using Super = CopiedTypeVisitor<SearchNonTrivialToCopyField, false>;
+
+  SearchNonTrivialToCopyField(const Expr *E, Sema &S) : E(E), S(S) {}
+
+  void visitWithKind(QualType::PrimitiveCopyKind PCK, QualType FT,
+                     SourceLocation SL) {
+    if (const auto *AT = asDerived().getContext().getAsArrayType(FT)) {
+      asDerived().visitArray(PCK, AT, SL);
+      return;
+    }
+
+    Super::visitWithKind(PCK, FT, SL);
+  }
+
+  void visitARCStrong(QualType FT, SourceLocation SL) {
+    S.DiagRuntimeBehavior(SL, E, S.PDiag(diag::note_nontrivial_field) << 0);
+  }
+  void visitARCWeak(QualType FT, SourceLocation SL) {
+    S.DiagRuntimeBehavior(SL, E, S.PDiag(diag::note_nontrivial_field) << 0);
+  }
+  void visitStruct(QualType FT, SourceLocation SL) {
+    for (const FieldDecl *FD : FT->castAs<RecordType>()->getDecl()->fields())
+      visit(FD->getType(), FD->getLocation());
+  }
+  void visitArray(QualType::PrimitiveCopyKind PCK, const ArrayType *AT,
+                  SourceLocation SL) {
+    visit(getContext().getBaseElementType(AT), SL);
+  }
+  void preVisit(QualType::PrimitiveCopyKind PCK, QualType FT,
+                SourceLocation SL) {}
+  void visitTrivial(QualType FT, SourceLocation SL) {}
+  void visitVolatileTrivial(QualType FT, SourceLocation SL) {}
+
+  static void diag(QualType RT, const Expr *E, Sema &S) {
+    SearchNonTrivialToCopyField(E, S).visitStruct(RT, SourceLocation());
+  }
+
+  ASTContext &getContext() { return S.getASTContext(); }
+
+  const Expr *E;
+  Sema &S;
+};
+
+}
+
 /// \brief Check for dangerous or invalid arguments to memset().
 ///
 /// This issues warnings on known problematic, dangerous or unspecified
@@ -7543,7 +7636,23 @@ void Sema::CheckMemaccessArguments(const CallExpr *Call,
         PDiag(diag::warn_arc_object_memaccess)
           << ArgIdx << FnName << PointeeTy
           << Call->getCallee()->getSourceRange());
-    else
+    else if (const auto *RT = PointeeTy->getAs<RecordType>()) {
+      if ((BId == Builtin::BImemset || BId == Builtin::BIbzero) &&
+          RT->getDecl()->isNonTrivialToPrimitiveDefaultInitialize()) {
+        DiagRuntimeBehavior(Dest->getExprLoc(), Dest,
+                            PDiag(diag::warn_cstruct_memaccess)
+                                << ArgIdx << FnName << PointeeTy << 0);
+        SearchNonTrivialToInitializeField::diag(PointeeTy, Dest, *this);
+      } else if ((BId == Builtin::BImemcpy || BId == Builtin::BImemmove) &&
+                 RT->getDecl()->isNonTrivialToPrimitiveCopy()) {
+        DiagRuntimeBehavior(Dest->getExprLoc(), Dest,
+                            PDiag(diag::warn_cstruct_memaccess)
+                                << ArgIdx << FnName << PointeeTy << 1);
+        SearchNonTrivialToCopyField::diag(PointeeTy, Dest, *this);
+      } else {
+        continue;
+      }
+    } else
       continue;
 
     DiagRuntimeBehavior(

clang/test/SemaObjC/warn-nontrivial-struct-memaccess.m

@@ -0,0 +1,39 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fobjc-runtime-has-weak -x objective-c -fobjc-arc -verify %s
+
+void *memset(void *, int, __SIZE_TYPE__);
+void bzero(void *, __SIZE_TYPE__);
+void *memcpy(void *, const void *, __SIZE_TYPE__);
+void *memmove(void *, const void *, __SIZE_TYPE__);
+
+struct Trivial {
+  int f0;
+  volatile int f1;
+};
+
+struct NonTrivial0 {
+  int f0;
+  __weak id f1; // expected-note 2 {{non-trivial to default-initialize}} expected-note 2 {{non-trivial to copy}}
+  volatile int f2;
+  id f3[10]; // expected-note 2 {{non-trivial to default-initialize}} expected-note 2 {{non-trivial to copy}}
+};
+
+struct NonTrivial1 {
+  id f0; // expected-note 2 {{non-trivial to default-initialize}} expected-note 2 {{non-trivial to copy}}
+  int f1;
+  struct NonTrivial0 f2;
+};
+
+void testTrivial(struct Trivial *d, struct Trivial *s) {
+  memset(d, 0, sizeof(struct Trivial));
+  bzero(d, sizeof(struct Trivial));
+  memcpy(d, s, sizeof(struct Trivial));
+  memmove(d, s, sizeof(struct Trivial));
+}
+
+void testNonTrivial1(struct NonTrivial1 *d, struct NonTrivial1 *s) {
+  memset(d, 0, sizeof(struct NonTrivial1)); // expected-warning {{that is not trivial to primitive-default-initialize}} expected-note {{explicitly cast the pointer to silence}}
+  memset((void *)d, 0, sizeof(struct NonTrivial1));
+  bzero(d, sizeof(struct NonTrivial1)); // expected-warning {{that is not trivial to primitive-default-initialize}} expected-note {{explicitly cast the pointer to silence}}
+  memcpy(d, s, sizeof(struct NonTrivial1)); // expected-warning {{that is not trivial to primitive-copy}} expected-note {{explicitly cast the pointer to silence}}
+  memmove(d, s, sizeof(struct NonTrivial1)); // expected-warning {{that is not trivial to primitive-copy}} expected-note {{explicitly cast the pointer to silence}}
+}