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PR41845: Detect and reject mismatched inner/outer pack expansion sizes 

in fold expressions rather than crashing.

llvm-svn: 360563
This commit is contained in:
Richard Smith 2019-05-13 08:31:14 +00:00
parent 1effa6c665
commit c7214f6510
7 changed files with 41 additions and 13 deletions
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13
clang/include/clang/AST/ExprCXX.h
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@ -4436,18 +4436,21 @@ class CXXFoldExpr : public Expr {
SourceLocation LParenLoc;
SourceLocation EllipsisLoc;
SourceLocation RParenLoc;
// When 0, the number of expansions is not known. Otherwise, this is one more
// than the number of expansions.
unsigned NumExpansions;
Stmt *SubExprs[2];
BinaryOperatorKind Opcode;
public:
CXXFoldExpr(QualType T, SourceLocation LParenLoc, Expr *LHS,
BinaryOperatorKind Opcode, SourceLocation EllipsisLoc, Expr *RHS,
SourceLocation RParenLoc)
SourceLocation RParenLoc, Optional<unsigned> NumExpansions)
: Expr(CXXFoldExprClass, T, VK_RValue, OK_Ordinary,
/*Dependent*/ true, true, true,
/*ContainsUnexpandedParameterPack*/ false),
LParenLoc(LParenLoc), EllipsisLoc(EllipsisLoc), RParenLoc(RParenLoc),
Opcode(Opcode) {
NumExpansions(NumExpansions ? *NumExpansions + 1 : 0), Opcode(Opcode) {
SubExprs[0] = LHS;
SubExprs[1] = RHS;
}
@ -4474,6 +4477,12 @@ public:
SourceLocation getEllipsisLoc() const { return EllipsisLoc; }
BinaryOperatorKind getOperator() const { return Opcode; }
Optional<unsigned> getNumExpansions() const {
if (NumExpansions)
return NumExpansions - 1;
return None;
}
SourceLocation getBeginLoc() const LLVM_READONLY { return LParenLoc; }
SourceLocation getEndLoc() const LLVM_READONLY { return RParenLoc; }

3
clang/include/clang/Sema/Sema.h
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@ -5204,7 +5204,8 @@ public:
ExprResult BuildCXXFoldExpr(SourceLocation LParenLoc, Expr *LHS,
BinaryOperatorKind Operator,
SourceLocation EllipsisLoc, Expr *RHS,
SourceLocation RParenLoc);
SourceLocation RParenLoc,
Optional<unsigned> NumExpansions);
ExprResult BuildEmptyCXXFoldExpr(SourceLocation EllipsisLoc,
BinaryOperatorKind Operator);

9
clang/lib/Sema/SemaTemplateVariadic.cpp
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@ -1176,15 +1176,18 @@ ExprResult Sema::ActOnCXXFoldExpr(SourceLocation LParenLoc, Expr *LHS,
}
BinaryOperatorKind Opc = ConvertTokenKindToBinaryOpcode(Operator);
return BuildCXXFoldExpr(LParenLoc, LHS, Opc, EllipsisLoc, RHS, RParenLoc);
return BuildCXXFoldExpr(LParenLoc, LHS, Opc, EllipsisLoc, RHS, RParenLoc,
None);
}
ExprResult Sema::BuildCXXFoldExpr(SourceLocation LParenLoc, Expr *LHS,
BinaryOperatorKind Operator,
SourceLocation EllipsisLoc, Expr *RHS,
SourceLocation RParenLoc) {
SourceLocation RParenLoc,
Optional<unsigned> NumExpansions) {
return new (Context) CXXFoldExpr(Context.DependentTy, LParenLoc, LHS,
Operator, EllipsisLoc, RHS, RParenLoc);
Operator, EllipsisLoc, RHS, RParenLoc,
NumExpansions);
}
ExprResult Sema::BuildEmptyCXXFoldExpr(SourceLocation EllipsisLoc,

17
clang/lib/Sema/TreeTransform.h
View File

@ -3254,9 +3254,10 @@ public:
ExprResult RebuildCXXFoldExpr(SourceLocation LParenLoc, Expr *LHS,
BinaryOperatorKind Operator,
SourceLocation EllipsisLoc, Expr *RHS,
SourceLocation RParenLoc) {
SourceLocation RParenLoc,
Optional<unsigned> NumExpansions) {
return getSema().BuildCXXFoldExpr(LParenLoc, LHS, Operator, EllipsisLoc,
RHS, RParenLoc);
RHS, RParenLoc, NumExpansions);
}
/// Build an empty C++1z fold-expression with the given operator.
@ -11823,7 +11824,8 @@ TreeTransform<Derived>::TransformCXXFoldExpr(CXXFoldExpr *E) {
// be expanded.
bool Expand = true;
bool RetainExpansion = false;
Optional<unsigned> NumExpansions;
Optional<unsigned> OrigNumExpansions = E->getNumExpansions(),
NumExpansions = OrigNumExpansions;
if (getDerived().TryExpandParameterPacks(E->getEllipsisLoc(),
Pattern->getSourceRange(),
Unexpanded,
@ -11852,7 +11854,7 @@ TreeTransform<Derived>::TransformCXXFoldExpr(CXXFoldExpr *E) {
return getDerived().RebuildCXXFoldExpr(
E->getBeginLoc(), LHS.get(), E->getOperator(), E->getEllipsisLoc(),
RHS.get(), E->getEndLoc());
RHS.get(), E->getEndLoc(), NumExpansions);
}
// The transform has determined that we should perform an elementwise
@ -11873,7 +11875,7 @@ TreeTransform<Derived>::TransformCXXFoldExpr(CXXFoldExpr *E) {
Result = getDerived().RebuildCXXFoldExpr(
E->getBeginLoc(), Out.get(), E->getOperator(), E->getEllipsisLoc(),
Result.get(), E->getEndLoc());
Result.get(), E->getEndLoc(), OrigNumExpansions);
if (Result.isInvalid())
return true;
}
@ -11890,7 +11892,8 @@ TreeTransform<Derived>::TransformCXXFoldExpr(CXXFoldExpr *E) {
Result = getDerived().RebuildCXXFoldExpr(
E->getBeginLoc(), LeftFold ? Result.get() : Out.get(),
E->getOperator(), E->getEllipsisLoc(),
LeftFold ? Out.get() : Result.get(), E->getEndLoc());
LeftFold ? Out.get() : Result.get(), E->getEndLoc(),
OrigNumExpansions);
} else if (Result.isUsable()) {
// We've got down to a single element; build a binary operator.
Result = getDerived().RebuildBinaryOperator(
@ -11915,7 +11918,7 @@ TreeTransform<Derived>::TransformCXXFoldExpr(CXXFoldExpr *E) {
Result = getDerived().RebuildCXXFoldExpr(
E->getBeginLoc(), Result.get(), E->getOperator(), E->getEllipsisLoc(),
Out.get(), E->getEndLoc());
Out.get(), E->getEndLoc(), OrigNumExpansions);
if (Result.isInvalid())
return true;
}

1
clang/lib/Serialization/ASTReaderStmt.cpp
View File

@ -1810,6 +1810,7 @@ void ASTStmtReader::VisitCXXFoldExpr(CXXFoldExpr *E) {
E->LParenLoc = ReadSourceLocation();
E->EllipsisLoc = ReadSourceLocation();
E->RParenLoc = ReadSourceLocation();
E->NumExpansions = Record.readInt();
E->SubExprs[0] = Record.readSubExpr();
E->SubExprs[1] = Record.readSubExpr();
E->Opcode = (BinaryOperatorKind)Record.readInt();

1
clang/lib/Serialization/ASTWriterStmt.cpp
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@ -1780,6 +1780,7 @@ void ASTStmtWriter::VisitCXXFoldExpr(CXXFoldExpr *E) {
Record.AddSourceLocation(E->LParenLoc);
Record.AddSourceLocation(E->EllipsisLoc);
Record.AddSourceLocation(E->RParenLoc);
Record.push_back(E->NumExpansions);
Record.AddStmt(E->SubExprs[0]);
Record.AddStmt(E->SubExprs[1]);
Record.push_back(E->Opcode);

10
clang/test/SemaTemplate/cxx1z-fold-expressions.cpp
View File

@ -92,3 +92,13 @@ template<typename ...T> constexpr auto spaceship3(T ...t) { return (t <=> ... <=
template<typename ...T> constexpr auto binary_conditional1(T ...t) { return (t ?: ...); } // expected-error {{expected expression}}
template<typename ...T> constexpr auto binary_conditional2(T ...t) { return (... ?: t); } // expected-error {{expected expression}}
template<typename ...T> constexpr auto binary_conditional3(T ...t) { return (t ?: ... ?: 0); } // expected-error {{expected expression}}
namespace PR41845 {
template <int I> struct Constant {};
template <int... Is> struct Sum {
template <int... Js> using type = Constant<((Is + Js) + ... + 0)>; // expected-error {{pack expansion contains parameter pack 'Js' that has a different length (1 vs. 2) from outer parameter packs}}
};
Sum<1>::type<1, 2> x; // expected-note {{instantiation of}}
}