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[clang][bytecode] Fix __builtin_strchr with unsigned chars #164410

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Merged
merged 1 commit into from
Oct 21, 2025
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[clang][bytecode] Fix __builtin_strchr with unsigned chars #164410

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10 changes: 8 additions & 2 deletions clang/lib/AST/ByteCode/InterpBuiltin.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2042,10 +2042,16 @@ static bool interp__builtin_memchr(InterpState &S, CodePtr OpPC,
}

if (ID == Builtin::BIstrchr || ID == Builtin::BI__builtin_strchr) {
int64_t DesiredTrunc;
if (S.getASTContext().CharTy->isSignedIntegerType())
DesiredTrunc =
Desired.trunc(S.getASTContext().getCharWidth()).getSExtValue();
else
DesiredTrunc =
Desired.trunc(S.getASTContext().getCharWidth()).getZExtValue();
// strchr compares directly to the passed integer, and therefore
// always fails if given an int that is not a char.
if (Desired !=
Desired.trunc(S.getASTContext().getCharWidth()).getSExtValue()) {
if (Desired != DesiredTrunc) {
S.Stk.push<Pointer>();
return true;
}
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2 changes: 2 additions & 0 deletions clang/test/SemaCXX/constexpr-string.cpp
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Expand Up @@ -7,6 +7,8 @@
// RUN: %clang_cc1 %s -triple armebv7-unknown-linux -std=c++2a -fsyntax-only -verify -pedantic -Wno-vla-extension -fno-signed-char
// RUN: %clang_cc1 %s -triple armebv7-unknown-linux -std=c++2a -fsyntax-only -verify -pedantic -Wno-vla-extension -fno-wchar -DNO_PREDEFINED_WCHAR_T

// RUN: %clang_cc1 %s -triple armebv7-unknown-linux -std=c++2a -fsyntax-only -verify -pedantic -Wno-vla-extension -fno-signed-char -fexperimental-new-constant-interpreter

# 9 "/usr/include/string.h" 1 3 4 // expected-warning {{this style of line directive is a GNU extension}}
extern "C" {
typedef decltype(sizeof(int)) size_t;
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