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[clang] Add an ABI_EXTENSION concept that is testable under -pedantic… #153506

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[clang] Add an ABI_EXTENSION concept that is testable under -pedantic… #153506

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[clang] Add an ABI_EXTENSION concept that is testable under -pedantic…
ojhunt Aug 13, 2025
9783fcf
Fix formatting
ojhunt Aug 14, 2025
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11 changes: 8 additions & 3 deletions clang/include/clang/Basic/Features.def
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Original file line number Diff line number Diff line change
Expand Up @@ -24,8 +24,8 @@
//
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@pcc pcc Aug 14, 2025

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Maybe also mention ABI_EXTENSION here?

//===----------------------------------------------------------------------===//

#if !defined(FEATURE) && !defined(EXTENSION)
# error Define either the FEATURE or EXTENSION macro to handle features
#if !defined(FEATURE) && !defined(EXTENSION) && !defined(ABI_EXTENSION)
# error Define either the FEATURE, EXTENSION, or ABI_EXTENSION macro to handle features
#endif

#ifndef FEATURE
Expand All @@ -36,6 +36,10 @@
#define EXTENSION(Name, Predicate)
#endif

#ifndef ABI_EXTENSION
#define ABI_EXTENSION(Name, Predicate)
#endif

FEATURE(speculative_load_hardening, LangOpts.SpeculativeLoadHardening)
FEATURE(address_sanitizer,
LangOpts.Sanitize.hasOneOf(SanitizerKind::Address |
Expand Down Expand Up @@ -148,7 +152,7 @@ FEATURE(thread_sanitizer, LangOpts.Sanitize.has(SanitizerKind::Thread))
FEATURE(dataflow_sanitizer, LangOpts.Sanitize.has(SanitizerKind::DataFlow))
FEATURE(scudo, LangOpts.Sanitize.hasOneOf(SanitizerKind::Scudo))
FEATURE(ptrauth_intrinsics, LangOpts.PointerAuthIntrinsics)
EXTENSION(ptrauth_qualifier, LangOpts.PointerAuthIntrinsics)
ABI_EXTENSION(ptrauth_qualifier, LangOpts.PointerAuthIntrinsics)
FEATURE(ptrauth_calls, LangOpts.PointerAuthCalls)
FEATURE(ptrauth_returns, LangOpts.PointerAuthReturns)
FEATURE(ptrauth_vtable_pointer_address_discrimination, LangOpts.PointerAuthVTPtrAddressDiscrimination)
Expand Down Expand Up @@ -385,3 +389,4 @@ EXTENSION(cxx_type_aware_allocators, true)

#undef EXTENSION
#undef FEATURE
#undef ABI_EXTENSION
6 changes: 5 additions & 1 deletion clang/lib/Frontend/FrontendActions.cpp
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Expand Up @@ -1183,11 +1183,15 @@ void DumpCompilerOptionsAction::ExecuteAction() {
OS << "\n\"extensions\" : [\n";
{
llvm::SmallString<128> Str;
#define EXTENSION(Name, Predicate) \
#define EXTENSION_OPTION(Name, Predicate) \
("\t{\"" #Name "\" : " + llvm::Twine(Predicate ? "true" : "false") + "},\n") \
.toVector(Str);
#define EXTENSION(Name, Predicate) EXTENSION_OPTION(Name, Predicate)
#define ABI_EXTENSION(Name, Predicate) EXTENSION_OPTION(Name, Predicate)
#include "clang/Basic/Features.def"
#undef EXTENSION
#undef ABI_EXTENSION
#undef EXTENSION_OPTION
// Remove the newline and comma from the last entry to ensure this remains
// valid JSON.
OS << Str.substr(0, Str.size() - 2);
Expand Down
21 changes: 14 additions & 7 deletions clang/lib/Lex/PPMacroExpansion.cpp
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Expand Up @@ -1109,19 +1109,26 @@ static bool HasExtension(const Preprocessor &PP, StringRef Extension) {
if (HasFeature(PP, Extension))
return true;

// Normalize the extension name, __foo__ becomes foo.
if (Extension.starts_with("__") && Extension.ends_with("__") &&
Extension.size() >= 4)
Extension = Extension.substr(2, Extension.size() - 4);

const LangOptions &LangOpts = PP.getLangOpts();
#define ABI_EXTENSION(Name, Predicate) .Case(#Name, Predicate)
bool IsABIExtension = llvm::StringSwitch<bool>(Extension)
#include "clang/Basic/Features.def"
.Default(false);
#undef ABI_EXTENSION
if (IsABIExtension)
return true;

// If the use of an extension results in an error diagnostic, extensions are
// effectively unavailable, so just return false here.
if (PP.getDiagnostics().getExtensionHandlingBehavior() >=
diag::Severity::Error)
return false;

const LangOptions &LangOpts = PP.getLangOpts();

// Normalize the extension name, __foo__ becomes foo.
if (Extension.starts_with("__") && Extension.ends_with("__") &&
Extension.size() >= 4)
Extension = Extension.substr(2, Extension.size() - 4);

// Because we inherit the feature list from HasFeature, this string switch
// must be less restrictive than HasFeature's.
#define EXTENSION(Name, Predicate) .Case(#Name, Predicate)
Expand Down
1 change: 1 addition & 0 deletions clang/test/Sema/ptrauth-qualifier.c
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@@ -1,5 +1,6 @@
// RUN: %clang_cc1 -triple arm64-apple-ios -std=c23 -fsyntax-only -verify -fptrauth-intrinsics %s
// RUN: %clang_cc1 -triple aarch64-linux-gnu -std=c23 -fsyntax-only -verify -fptrauth-intrinsics %s
// RUN: %clang_cc1 -triple aarch64-linux-gnu -std=c23 -fsyntax-only -verify -fptrauth-intrinsics -pedantic-errors -Wno-c2y-extensions %s

#if !__has_extension(ptrauth_qualifier)
// This error means that the __ptrauth qualifier availability test says that it
Expand Down