[clang] [Clang] Handle consteval expression in array bounds expressions (PR #66222)
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Wed Sep 13 08:54:18 PDT 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
<details>
<summary>Changes</summary>
The bounds of a c++ array is a _constant-expression_. And in C++ it is also a constant expression.
But we also support VLAs, ie arrays with non-constant bounds.
We need to take care to handle the case of a consteval function (which are specified to be only immediately called in non-constant contexts) that appear in arrays bounds.
This introduces `Sema::isAlwayConstantEvaluatedContext`, and a flag in ExpressionEvaluationContextRecord, such that immediate functions in array bounds are always immediately invoked.
Sema had both `isConstantEvaluatedContext` and
`isConstantEvaluated`, so I took the opportunity to cleanup that.
The change in `TimeProfilerTest.cpp` is an unfortunate manifestation of the problem that #66203 seeks to address.
Fixes #65520
--
Patch is 20.71 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/66222.diff
11 Files Affected:
- (modified) clang/docs/ReleaseNotes.rst (+4)
- (modified) clang/include/clang/Parse/Parser.h (+1)
- (modified) clang/include/clang/Sema/Sema.h (+32-28)
- (modified) clang/lib/Parse/ParseDecl.cpp (+1-1)
- (modified) clang/lib/Parse/ParseExpr.cpp (+9)
- (modified) clang/lib/Sema/SemaCUDA.cpp (+1-1)
- (modified) clang/lib/Sema/SemaChecking.cpp (+30-25)
- (modified) clang/lib/Sema/SemaExpr.cpp (+2-2)
- (modified) clang/lib/Sema/TreeTransform.h (+3)
- (modified) clang/test/SemaCXX/cxx2a-consteval.cpp (+15)
- (modified) clang/unittests/Support/TimeProfilerTest.cpp (+1)
<pre>
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 3cdad2f7b9f0e5a..1d2c0830b2910d5 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -281,6 +281,10 @@ Bug Fixes to C++ Support
a non-template inner-class between the function and the class template.
(`#65810 <https://github.com/llvm/llvm-project/issues/65810>`_)
+- Fix a crash when calling a consteval function in an expression used as
+ the size of an array.
+ (`#65520 <https://github.com/llvm/llvm-project/issues/65520>`_)
+
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
- Fixed an import failure of recursive friend class template.
diff --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h
index f599b8b98d031fb..7303db939de7fe0 100644
--- a/clang/include/clang/Parse/Parser.h
+++ b/clang/include/clang/Parse/Parser.h
@@ -1766,6 +1766,7 @@ class Parser : public CodeCompletionHandler {
ExprResult ParseConstantExpressionInExprEvalContext(
TypeCastState isTypeCast = NotTypeCast);
ExprResult ParseConstantExpression();
+ ExprResult ParseArrayBoundExpression();
ExprResult ParseCaseExpression(SourceLocation CaseLoc);
ExprResult ParseConstraintExpression();
ExprResult
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 304108df9f8d029..77a8cb67be16c91 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -1062,20 +1062,6 @@ class Sema final {
}
};
- /// Whether the AST is currently being rebuilt to correct immediate
- /// invocations. Immediate invocation candidates and references to consteval
- /// functions aren't tracked when this is set.
- bool RebuildingImmediateInvocation = false;
-
- /// Used to change context to isConstantEvaluated without pushing a heavy
- /// ExpressionEvaluationContextRecord object.
- bool isConstantEvaluatedOverride;
-
- bool isConstantEvaluated() const {
- return ExprEvalContexts.back().isConstantEvaluated() ||
- isConstantEvaluatedOverride;
- }
-
/// RAII object to handle the state changes required to synthesize
/// a function body.
class SynthesizedFunctionScope {
@@ -1361,6 +1347,10 @@ class Sema final {
bool IsCurrentlyCheckingDefaultArgumentOrInitializer = false;
+ // We are in a constant context, but we also allow
+ // non constant expressions, for example for array bounds (which may be VLAs).
+ bool InConditionallyConstantEvaluateContext = false;
+
// When evaluating immediate functions in the initializer of a default
// argument or default member initializer, this is the declaration whose
// default initializer is being evaluated and the location of the call
@@ -9844,30 +9834,44 @@ class Sema final {
/// diagnostics that will be suppressed.
std::optional<sema::TemplateDeductionInfo *> isSFINAEContext() const;
- /// Determines whether we are currently in a context that
- /// is not evaluated as per C++ [expr] p5.
- bool isUnevaluatedContext() const {
+ /// Whether the AST is currently being rebuilt to correct immediate
+ /// invocations. Immediate invocation candidates and references to consteval
+ /// functions aren't tracked when this is set.
+ bool RebuildingImmediateInvocation = false;
+
+ /// Used to change context to isConstantEvaluated without pushing a heavy
+ /// ExpressionEvaluationContextRecord object.
+ bool isConstantEvaluatedOverride;
+
+ const ExpressionEvaluationContextRecord &currentEvaluationContext() const {
assert(!ExprEvalContexts.empty() &&
"Must be in an expression evaluation context");
- return ExprEvalContexts.back().isUnevaluated();
- }
+ return ExprEvalContexts.back();
+ };
bool isConstantEvaluatedContext() const {
- assert(!ExprEvalContexts.empty() &&
- "Must be in an expression evaluation context");
- return ExprEvalContexts.back().isConstantEvaluated();
+ return currentEvaluationContext().isConstantEvaluated() ||
+ isConstantEvaluatedOverride;
+ }
+
+ bool isAlwaysConstantEvaluatedContext() const {
+ const ExpressionEvaluationContextRecord &Ctx = currentEvaluationContext();
+ return (Ctx.isConstantEvaluated() || isConstantEvaluatedOverride) &&
+ !Ctx.InConditionallyConstantEvaluateContext;
+ }
+
+ /// Determines whether we are currently in a context that
+ /// is not evaluated as per C++ [expr] p5.
+ bool isUnevaluatedContext() const {
+ return currentEvaluationContext().isUnevaluated();
}
bool isImmediateFunctionContext() const {
- assert(!ExprEvalContexts.empty() &&
- "Must be in an expression evaluation context");
- return ExprEvalContexts.back().isImmediateFunctionContext();
+ return currentEvaluationContext().isImmediateFunctionContext();
}
bool isCheckingDefaultArgumentOrInitializer() const {
- assert(!ExprEvalContexts.empty() &&
- "Must be in an expression evaluation context");
- const ExpressionEvaluationContextRecord &Ctx = ExprEvalContexts.back();
+ const ExpressionEvaluationContextRecord &Ctx = currentEvaluationContext();
return (Ctx.Context ==
ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed) ||
Ctx.IsCurrentlyCheckingDefaultArgumentOrInitializer;
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 748b9d53c9f5b33..5114e181582d91a 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -7687,7 +7687,7 @@ void Parser::ParseBracketDeclarator(Declarator &D) {
// Parse the constant-expression or assignment-expression now (depending
// on dialect).
if (getLangOpts().CPlusPlus) {
- NumElements = ParseConstantExpression();
+ NumElements = ParseArrayBoundExpression();
} else {
EnterExpressionEvaluationContext Unevaluated(
Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);
diff --git a/clang/lib/Parse/ParseExpr.cpp b/clang/lib/Parse/ParseExpr.cpp
index f8bf785da2896a3..e6de742a01f3f6d 100644
--- a/clang/lib/Parse/ParseExpr.cpp
+++ b/clang/lib/Parse/ParseExpr.cpp
@@ -221,6 +221,15 @@ ExprResult Parser::ParseConstantExpression() {
return ParseConstantExpressionInExprEvalContext(NotTypeCast);
}
+ExprResult Parser::ParseArrayBoundExpression() {
+ EnterExpressionEvaluationContext ConstantEvaluated(
+ Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);
+ // If we parse the bound of a VLA... we parse a non-constant
+ // constant-expression!
+ Actions.ExprEvalContexts.back().InConditionallyConstantEvaluateContext = true;
+ return ParseConstantExpressionInExprEvalContext(NotTypeCast);
+}
+
ExprResult Parser::ParseCaseExpression(SourceLocation CaseLoc) {
EnterExpressionEvaluationContext ConstantEvaluated(
Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);
diff --git a/clang/lib/Sema/SemaCUDA.cpp b/clang/lib/Sema/SemaCUDA.cpp
index 88f5484575db17a..bc676be371b8cf3 100644
--- a/clang/lib/Sema/SemaCUDA.cpp
+++ b/clang/lib/Sema/SemaCUDA.cpp
@@ -803,7 +803,7 @@ bool Sema::CheckCUDACall(SourceLocation Loc, FunctionDecl *Callee) {
assert(getLangOpts().CUDA && "Should only be called during CUDA compilation");
assert(Callee && "Callee may not be null.");
- auto &ExprEvalCtx = ExprEvalContexts.back();
+ const auto &ExprEvalCtx = currentEvaluationContext();
if (ExprEvalCtx.isUnevaluated() || ExprEvalCtx.isConstantEvaluated())
return true;
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index fad70223362eddd..5208dbd9d3c8f58 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -1068,7 +1068,7 @@ static bool ProcessFormatStringLiteral(const Expr *FormatExpr,
void Sema::checkFortifiedBuiltinMemoryFunction(FunctionDecl *FD,
CallExpr *TheCall) {
if (TheCall->isValueDependent() || TheCall->isTypeDependent() ||
- isConstantEvaluated())
+ isConstantEvaluatedContext())
return;
bool UseDABAttr = false;
@@ -3175,7 +3175,7 @@ bool Sema::CheckCDEBuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
bool Sema::CheckARMCoprocessorImmediate(const TargetInfo &TI,
const Expr *CoprocArg, bool WantCDE) {
- if (isConstantEvaluated())
+ if (isConstantEvaluatedContext())
return false;
// We can't check the value of a dependent argument.
@@ -6595,7 +6595,7 @@ static void CheckNonNullArguments(Sema &S,
assert((FDecl || Proto) && "Need a function declaration or prototype");
// Already checked by constant evaluator.
- if (S.isConstantEvaluated())
+ if (S.isConstantEvaluatedContext())
return;
// Check the attributes attached to the method/function itself.
llvm::SmallBitVector NonNullArgs;
@@ -8952,7 +8952,7 @@ bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
/// TheCall is a constant expression in the range [Low, High].
bool Sema::SemaBuiltinConstantArgRange(CallExpr *TheCall, int ArgNum,
int Low, int High, bool RangeIsError) {
- if (isConstantEvaluated())
+ if (isConstantEvaluatedContext())
return false;
llvm::APSInt Result;
@@ -9666,7 +9666,7 @@ checkFormatStringExpr(Sema &S, const Expr *E, ArrayRef<const Expr *> Args,
llvm::SmallBitVector &CheckedVarArgs,
UncoveredArgHandler &UncoveredArg, llvm::APSInt Offset,
bool IgnoreStringsWithoutSpecifiers = false) {
- if (S.isConstantEvaluated())
+ if (S.isConstantEvaluatedContext())
return SLCT_NotALiteral;
tryAgain:
assert(Offset.isSigned() && "invalid offset");
@@ -9706,8 +9706,8 @@ checkFormatStringExpr(Sema &S, const Expr *E, ArrayRef<const Expr *> Args,
bool CheckLeft = true, CheckRight = true;
bool Cond;
- if (C->getCond()->EvaluateAsBooleanCondition(Cond, S.getASTContext(),
- S.isConstantEvaluated())) {
+ if (C->getCond()->EvaluateAsBooleanCondition(
+ Cond, S.getASTContext(), S.isConstantEvaluatedContext())) {
if (Cond)
CheckRight = false;
else
@@ -9971,9 +9971,11 @@ checkFormatStringExpr(Sema &S, const Expr *E, ArrayRef<const Expr *> Args,
Expr::EvalResult LResult, RResult;
bool LIsInt = BinOp->getLHS()->EvaluateAsInt(
- LResult, S.Context, Expr::SE_NoSideEffects, S.isConstantEvaluated());
+ LResult, S.Context, Expr::SE_NoSideEffects,
+ S.isConstantEvaluatedContext());
bool RIsInt = BinOp->getRHS()->EvaluateAsInt(
- RResult, S.Context, Expr::SE_NoSideEffects, S.isConstantEvaluated());
+ RResult, S.Context, Expr::SE_NoSideEffects,
+ S.isConstantEvaluatedContext());
if (LIsInt != RIsInt) {
BinaryOperatorKind BinOpKind = BinOp->getOpcode();
@@ -10001,7 +10003,7 @@ checkFormatStringExpr(Sema &S, const Expr *E, ArrayRef<const Expr *> Args,
Expr::EvalResult IndexResult;
if (ASE->getRHS()->EvaluateAsInt(IndexResult, S.Context,
Expr::SE_NoSideEffects,
- S.isConstantEvaluated())) {
+ S.isConstantEvaluatedContext())) {
sumOffsets(Offset, IndexResult.Val.getInt(), BO_Add,
/*RHS is int*/ true);
E = ASE->getBase();
@@ -13928,7 +13930,7 @@ static bool CheckTautologicalComparison(Sema &S, BinaryOperator *E,
return false;
IntRange OtherValueRange = GetExprRange(
- S.Context, Other, S.isConstantEvaluated(), /*Approximate*/ false);
+ S.Context, Other, S.isConstantEvaluatedContext(), /*Approximate*/ false);
QualType OtherT = Other->getType();
if (const auto *AT = OtherT->getAs<AtomicType>())
@@ -14143,8 +14145,9 @@ static void AnalyzeComparison(Sema &S, BinaryOperator *E) {
}
// Otherwise, calculate the effective range of the signed operand.
- IntRange signedRange = GetExprRange(
- S.Context, signedOperand, S.isConstantEvaluated(), /*Approximate*/ true);
+ IntRange signedRange =
+ GetExprRange(S.Context, signedOperand, S.isConstantEvaluatedContext(),
+ /*Approximate*/ true);
// Go ahead and analyze implicit conversions in the operands. Note
// that we skip the implicit conversions on both sides.
@@ -14162,7 +14165,7 @@ static void AnalyzeComparison(Sema &S, BinaryOperator *E) {
if (E->isEqualityOp()) {
unsigned comparisonWidth = S.Context.getIntWidth(T);
IntRange unsignedRange =
- GetExprRange(S.Context, unsignedOperand, S.isConstantEvaluated(),
+ GetExprRange(S.Context, unsignedOperand, S.isConstantEvaluatedContext(),
/*Approximate*/ true);
// We should never be unable to prove that the unsigned operand is
@@ -15026,7 +15029,7 @@ static void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
if (Target->isUnsaturatedFixedPointType()) {
Expr::EvalResult Result;
if (E->EvaluateAsFixedPoint(Result, S.Context, Expr::SE_AllowSideEffects,
- S.isConstantEvaluated())) {
+ S.isConstantEvaluatedContext())) {
llvm::APFixedPoint Value = Result.Val.getFixedPoint();
llvm::APFixedPoint MaxVal = S.Context.getFixedPointMax(T);
llvm::APFixedPoint MinVal = S.Context.getFixedPointMin(T);
@@ -15041,7 +15044,7 @@ static void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
}
} else if (Target->isIntegerType()) {
Expr::EvalResult Result;
- if (!S.isConstantEvaluated() &&
+ if (!S.isConstantEvaluatedContext() &&
E->EvaluateAsFixedPoint(Result, S.Context,
Expr::SE_AllowSideEffects)) {
llvm::APFixedPoint FXResult = Result.Val.getFixedPoint();
@@ -15064,7 +15067,7 @@ static void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
} else if (Target->isUnsaturatedFixedPointType()) {
if (Source->isIntegerType()) {
Expr::EvalResult Result;
- if (!S.isConstantEvaluated() &&
+ if (!S.isConstantEvaluatedContext() &&
E->EvaluateAsInt(Result, S.Context, Expr::SE_AllowSideEffects)) {
llvm::APSInt Value = Result.Val.getInt();
@@ -15090,8 +15093,9 @@ static void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
if (SourceBT && TargetBT && SourceBT->isIntegerType() &&
TargetBT->isFloatingType() && !IsListInit) {
// Determine the number of precision bits in the source integer type.
- IntRange SourceRange = GetExprRange(S.Context, E, S.isConstantEvaluated(),
- /*Approximate*/ true);
+ IntRange SourceRange =
+ GetExprRange(S.Context, E, S.isConstantEvaluatedContext(),
+ /*Approximate*/ true);
unsigned int SourcePrecision = SourceRange.Width;
// Determine the number of precision bits in the
@@ -15159,8 +15163,8 @@ static void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
IntRange SourceTypeRange =
IntRange::forTargetOfCanonicalType(S.Context, Source);
- IntRange LikelySourceRange =
- GetExprRange(S.Context, E, S.isConstantEvaluated(), /*Approximate*/ true);
+ IntRange LikelySourceRange = GetExprRange(
+ S.Context, E, S.isConstantEvaluatedContext(), /*Approximate*/ true);
IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
if (LikelySourceRange.Width > TargetRange.Width) {
@@ -15168,7 +15172,7 @@ static void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
// TODO: this should happen for bitfield stores, too.
Expr::EvalResult Result;
if (E->EvaluateAsInt(Result, S.Context, Expr::SE_AllowSideEffects,
- S.isConstantEvaluated())) {
+ S.isConstantEvaluatedContext())) {
llvm::APSInt Value(32);
Value = Result.Val.getInt();
@@ -16032,7 +16036,8 @@ class SequenceChecker : public ConstEvaluatedExprVisitor<SequenceChecker> {
if (!EvalOK || E->isValueDependent())
return false;
EvalOK = E->EvaluateAsBooleanCondition(
- Result, Self.SemaRef.Context, Self.SemaRef.isConstantEvaluated());
+ Result, Self.SemaRef.Context,
+ Self.SemaRef.isConstantEvaluatedContext());
return EvalOK;
}
@@ -17159,7 +17164,7 @@ void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
const ArraySubscriptExpr *ASE,
bool AllowOnePastEnd, bool IndexNegated) {
// Already diagnosed by the constant evaluator.
- if (isConstantEvaluated())
+ if (isConstantEvaluatedContext())
return;
IndexExpr = IndexExpr->IgnoreParenImpCasts();
@@ -18548,7 +18553,7 @@ void Sema::CheckArgumentWithTypeTag(const ArgumentWithTypeTagAttr *Attr,
TypeTagData TypeInfo;
if (!GetMatchingCType(ArgumentKind, TypeTagExpr, Context,
TypeTagForDatatypeMagicValues.get(), FoundWrongKind,
- TypeInfo, isConstantEvaluated())) {
+ TypeInfo, isConstantEvaluatedContext())) {
if (FoundWrongKind)
Diag(TypeTagExpr->getExprLoc(),
diag::warn_type_tag_for_datatype_wrong_kind)
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 92496b03ecabe54..667444917a9b31e 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -18282,7 +18282,7 @@ void Sema::MarkExpressionAsImmediateEscalating(Expr *E) {
ExprResult Sema::CheckForImmediateInvocation(ExprResult E, FunctionDecl *Decl) {
if (isUnevaluatedContext() || !E.isUsable() || !Decl ||
- !Decl->isImmediateFunction() || isConstantEvaluated() ||
+ !Decl->isImmediateFunction() || isAlwaysConstantEvaluatedContext() ||
isCheckingDefaultArgumentOrInitializer() ||
RebuildingImmediateInvocation || isImmediateFunctionContext())
return E;
@@ -20668,7 +20668,7 @@ void Sema::MarkDeclRefReferenced(DeclRefExpr *E, const Expr *Base) {
OdrUse = false;
if (auto *FD = dyn_cast<FunctionDecl>(E->getDecl())) {
- if (!isUnevaluatedContext() && !isConstantEvaluated() &&
+ if (!isUnevaluatedContext() && !isConstantEvaluatedContext() &&
!isImmediateFunctionContext() &&
!isCheckingDefaultArgumentOrInitializer() &&
FD->isImmediateFunction() && !RebuildingImmediateInvocation &&
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 603a23275889f21..39ac6e9cfbcdcce 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -5486,6 +5486,9 @@ TreeTransform<Derived>::TransformDependentSizedArrayType(TypeLocBuilder &TLB,
EnterExpressionEvaluationContext Unevaluated(
SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
+ // VLA bounds are not truly constant.
+ SemaRef.ExprEvalContexts.back().InConditionallyConstantEvaluateContext = true;
+
// Prefer the expression from the TypeLoc; the other may have been uniqued.
Expr *origSize = TL.getSizeExpr();
if (!origSize) origSize = T->getSizeExpr();
diff --git a/clang/test/SemaCX...
<truncated>
</pre>
</details>
https://github.com/llvm/llvm-project/pull/66222
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