[Clang] prevent assertion failure in value-dependent initializer expressions

[a-tarasyuk]

Fixes #112140

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CXXConstructExpr 0x14209e580 'const S':'const struct S' contains-errors 'void (const int &)' list `-CXXDefaultArgExpr 0x14209e500 'const int' contains-errors `-RecoveryExpr 0x14209daf0 'const int' contains-errors 

This change resolves an issue with evaluating ArrayFiller initializers in dependent contexts, especially when they involve a RecoveryExpr. In certain cases, ArrayFiller initializers containing a RecoveryExpr from earlier errors are incorrectly passed to EvaluateInPlace, causing evaluation failures when they are value-dependent.

When this is the case, the initializer is processed through EvaluateDependentExpr, which prevents unnecessary evaluation attempts and ensures proper handling of value-dependent initializers in ArrayFillers.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Oleksandr T. (a-tarasyuk)

Changes

Fixes #112140

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Full diff: https://github.com/llvm/llvm-project/pull/112612.diff

3 Files Affected:

• (modified) clang/docs/ReleaseNotes.rst (+1)
• (modified) clang/lib/AST/ExprConstant.cpp (+3)
• (modified) clang/test/SemaCXX/constant-expression-cxx11.cpp (+10)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 817e3abef8d566..1cbf95f0b034d4 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -517,6 +517,7 @@ Bug Fixes to C++ Support certain situations. (#GH47400), (#GH90896) - Fix erroneous templated array size calculation leading to crashes in generated code. (#GH41441) - During the lookup for a base class name, non-type names are ignored. (#GH16855) +- Fixed an assertion failure when evaluating constant expressions in value-dependent initializers (#GH112140) Bug Fixes to AST Handling ^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp index 52a7f5778ce6d2..62d88f0f82b760 100644 --- a/clang/lib/AST/ExprConstant.cpp +++ b/clang/lib/AST/ExprConstant.cpp @@ -11536,6 +11536,9 @@ bool ArrayExprEvaluator::VisitCXXParenListOrInitListExpr( LValue Subobject = This; Subobject.addArray(Info, ExprToVisit, CAT); auto Eval = [&](const Expr *Init, unsigned ArrayIndex) { + if (Init->isValueDependent()) + return EvaluateDependentExpr(Init, Info); + if (!EvaluateInPlace(Result.getArrayInitializedElt(ArrayIndex), Info, Subobject, Init) || !HandleLValueArrayAdjustment(Info, Init, Subobject, diff --git a/clang/test/SemaCXX/constant-expression-cxx11.cpp b/clang/test/SemaCXX/constant-expression-cxx11.cpp index e2ea984b37cd04..e01aaff1459e88 100644 --- a/clang/test/SemaCXX/constant-expression-cxx11.cpp +++ b/clang/test/SemaCXX/constant-expression-cxx11.cpp @@ -2564,3 +2564,13 @@ GH50055::E2 GlobalInitNotCE2 = GH50055::testDefaultArgForParam(); // ok, not a c constexpr GH50055::E2 GlobalInitCE = (GH50055::E2)-1; // expected-error@-1 {{constexpr variable 'GlobalInitCE' must be initialized by a constant expression}} // expected-note@-2 {{integer value -1 is outside the valid range of values [0, 7] for the enumeration type 'E2'}} + +namespace GH { +struct S { + constexpr S(const int &a = ) { } // expected-error {{expected expression}} +}; + +void foo() { + constexpr S s[2] = { }; // expected-error {{constexpr variable 's' must be initialized by a constant expression}} +} +} 

[cor3ntin]

LGTM modulo comment.
Thanks!

[cor3ntin]

There is a description so I'll merge. Shafik can review post commit if needs be.
Thanks!

[shafik]

LGTM, thank you for adding more details to the summary