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[clang][bytecode] Typecheck called function pointers more thorougly #159757

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Merged
merged 1 commit into from
Sep 19, 2025
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[clang][bytecode] Typecheck called function pointers more thorougly #159757

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2 changes: 0 additions & 2 deletions clang/lib/AST/ByteCode/Context.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -446,8 +446,6 @@ Context::getOverridingFunction(const CXXRecordDecl *DynamicDecl,

const Function *Context::getOrCreateFunction(const FunctionDecl *FuncDecl) {
assert(FuncDecl);
FuncDecl = FuncDecl->getMostRecentDecl();

if (const Function *Func = P->getFunction(FuncDecl))
return Func;

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13 changes: 10 additions & 3 deletions clang/lib/AST/ByteCode/Interp.cpp
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Expand Up @@ -1750,9 +1750,8 @@ bool CallPtr(InterpState &S, CodePtr OpPC, uint32_t ArgSize,
const Pointer &Ptr = S.Stk.pop<Pointer>();

if (Ptr.isZero()) {
const auto *E = cast<CallExpr>(S.Current->getExpr(OpPC));
S.FFDiag(E, diag::note_constexpr_null_callee)
<< const_cast<Expr *>(E->getCallee()) << E->getSourceRange();
S.FFDiag(S.Current->getSource(OpPC), diag::note_constexpr_null_callee)
<< const_cast<Expr *>(CE->getCallee()) << CE->getSourceRange();
return false;
}

Expand All @@ -1778,6 +1777,14 @@ bool CallPtr(InterpState &S, CodePtr OpPC, uint32_t ArgSize,
return false;
}

// Can happen when casting function pointers around.
QualType CalleeType = CE->getCallee()->getType();
if (CalleeType->isPointerType() &&
!S.getASTContext().hasSameFunctionTypeIgnoringExceptionSpec(
F->getDecl()->getType(), CalleeType->getPointeeType())) {
return false;
}

assert(ArgSize >= F->getWrittenArgSize());
uint32_t VarArgSize = ArgSize - F->getWrittenArgSize();

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18 changes: 8 additions & 10 deletions clang/test/AST/ByteCode/functions.cpp
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@@ -1,9 +1,9 @@
// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -pedantic -verify=expected,both %s
// RUN: %clang_cc1 -std=c++14 -fexperimental-new-constant-interpreter -pedantic -verify=expected,both %s
// RUN: %clang_cc1 -std=c++20 -fexperimental-new-constant-interpreter -pedantic -verify=expected,both %s
// RUN: %clang_cc1 -pedantic -verify=ref,both %s
// RUN: %clang_cc1 -pedantic -std=c++14 -verify=ref,both %s
// RUN: %clang_cc1 -pedantic -std=c++20 -verify=ref,both %s
// RUN: %clang_cc1 -pedantic -verify=expected,both %s -fexperimental-new-constant-interpreter
// RUN: %clang_cc1 -std=c++14 -pedantic -verify=expected,both %s -fexperimental-new-constant-interpreter
// RUN: %clang_cc1 -std=c++20 -pedantic -verify=expected,both %s -fexperimental-new-constant-interpreter
// RUN: %clang_cc1 -pedantic -verify=ref,both %s
// RUN: %clang_cc1 -std=c++14 -pedantic -verify=ref,both %s
// RUN: %clang_cc1 -std=c++20 -pedantic -verify=ref,both %s

#define fold(x) (__builtin_constant_p(0) ? (x) : (x))

Expand Down Expand Up @@ -672,10 +672,8 @@ namespace FunctionCast {
constexpr int test4 = fold(IntFn(DoubleFn(f)))();
constexpr int test5 = IntFn(fold(DoubleFn(f)))(); // both-error {{constant expression}} \
// both-note {{cast that performs the conversions of a reinterpret_cast is not allowed in a constant expression}}
// FIXME: Interpreter is less strict here.
constexpr int test6 = fold(IntPtrFn(f2))() == nullptr; // ref-error {{constant expression}}
// FIXME: The following crashes interpreter
// constexpr int test6 = fold(IntFn(f3)());
constexpr int test6 = fold(IntPtrFn(f2))() == nullptr; // both-error {{constant expression}}
constexpr int test7 = fold(IntFn(f3)()); // both-error {{must be initialized by a constant expression}}
}

#if __cplusplus >= 202002L
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