[clang] Add an ABI_EXTENSION concept that is testable under -pedantic… #153506
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…-errors This is a targeted change to allow us to specify that an extension test should return true even if -pedantic-errors is enabled. In the longer term we may want to consider changing the behavior of -pedantic-errors to not gate __has_extension checks, and become more in line with `-Wpedantic -Werror`.
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✅ With the latest revision this PR passed the C/C++ code formatter. |
llvmbot
added
clang
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@llvm/pr-subscribers-clang Author: Oliver Hunt (ojhunt) Changes…-errors This is a targeted change to allow us to specify that an extension test should return true even if -pedantic-errors is enabled. In the longer term we may want to consider changing the behavior of -pedantic-errors to not gate __has_extension checks, and become more in line with Full diff: https://github.com/llvm/llvm-project/pull/153506.diff 4 Files Affected:
diff --git a/clang/include/clang/Basic/Features.def b/clang/include/clang/Basic/Features.def
index c58e3f2400adc..04ed820b4213a 100644
--- a/clang/include/clang/Basic/Features.def
+++ b/clang/include/clang/Basic/Features.def
@@ -24,8 +24,8 @@
//
//===----------------------------------------------------------------------===//
-#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
@@ -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 |
@@ -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)
@@ -385,3 +389,4 @@ EXTENSION(cxx_type_aware_allocators, true)
#undef EXTENSION
#undef FEATURE
+#undef ABI_EXTENSION
diff --git a/clang/lib/Frontend/FrontendActions.cpp b/clang/lib/Frontend/FrontendActions.cpp
index 685a9bbf2cde9..c925e1f8a1331 100644
--- a/clang/lib/Frontend/FrontendActions.cpp
+++ b/clang/lib/Frontend/FrontendActions.cpp
@@ -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);
diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index 6f12ac80d677e..7cae6acc081c0 100644
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -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)
diff --git a/clang/test/Sema/ptrauth-qualifier.c b/clang/test/Sema/ptrauth-qualifier.c
index 5d932b724f07a..358666025fca5 100644
--- a/clang/test/Sema/ptrauth-qualifier.c
+++ b/clang/test/Sema/ptrauth-qualifier.c
@@ -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
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pcc
reviewed
Aug 14, 2025
| // features, whereas EXTENSION(...) should be used for clang extensions. Note | ||
| // that many of the identifiers in this file don't follow this rule for backward | ||
| // compatibility reasons. | ||
| // |
There was a problem hiding this comment.
Maybe also mention ABI_EXTENSION here?
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@AaronBallman I'm not sure this is the correct approach but will leave it up for now |
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Closing, as for the current critical case (ptrauth) we're keeping the tests as a feature when the target is arm64e, and adding a |
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…-errors
This is a targeted change to allow us to specify that an extension test should return true even if -pedantic-errors is enabled.
In the longer term we may want to consider changing the behavior of -pedantic-errors to not gate __has_extension checks, and become more in line with
-Wpedantic -Werror.