Revert "[C2y] Support WG14 N3457, the __COUNTER__ macro (llvm#162662)"

ronlieb · ronlieb · commit 0e0ec981255d · 2025-11-04T11:37:07.000-06:00
This reverts commit df1d786.
diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
@@ -382,9 +382,7 @@ Builtin Macros
 
 ``__COUNTER__``
   Defined to an integer value that starts at zero and is incremented each time
-  the ``__COUNTER__`` macro is expanded. This is a standard feature in C2y but
-  is an extension in earlier language modes and in C++. This macro can only be
-  expanded 2147483647 times at most.
+  the ``__COUNTER__`` macro is expanded.
 
 ``__INCLUDE_LEVEL__``
   Defined to an integral value that is the include depth of the file currently
@@ -1820,7 +1818,6 @@ Octal literals prefixed with ``0o`` or ``0O``                                  C
 ``_Countof`` (N3369, N3469)                                                    C2y           C89
 ``_Generic`` with a type operand (N3260)                                       C2y           C89, C++
 ``++``/``--`` on ``_Complex`` value (N3259)                                    C2y           C89, C++
-``__COUNTER__`` (N3457)                                                        C2y           C89, C++
 ============================================= ================================ ============= =============
 
 Builtin type aliases
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
@@ -196,11 +196,6 @@ C2y Feature Support
   function or variable within an extern inline function is no longer a
   constraint per `WG14 N3622 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3622.txt>`_.
 - Clang now supports `N3355 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3355.htm>`_ Named Loops.
-- Clang's implementation of ``__COUNTER__`` was updated to conform to
-  `WG14 N3457 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3457.htm>`_.
-  This includes adding pedantic warnings for the feature being an extension in
-  other language modes as well as an error when the counter is expanded more
-  than 2147483647 times.
 
 C23 Feature Support
 ^^^^^^^^^^^^^^^^^^^
diff --git a/clang/include/clang/Basic/DiagnosticLexKinds.td b/clang/include/clang/Basic/DiagnosticLexKinds.td
@@ -90,14 +90,6 @@ def err_unterminated___pragma : Error<"missing terminating ')' character">;
 
 def err_conflict_marker : Error<"version control conflict marker in file">;
 
-def err_counter_overflow : Error<
-  "'__COUNTER__' value cannot exceed 2'147'483'647">;
-def ext_counter : Extension<
-  "'__COUNTER__' is a C2y extension">, InGroup<C2y>;
-def warn_counter : Warning<
-  "'__COUNTER__' is incompatible with standards before C2y">,
-  InGroup<CPre2yCompat>, DefaultIgnore;
-
 def err_raw_delim_too_long : Error<
   "raw string delimiter longer than 16 characters"
   "; use PREFIX( )PREFIX to delimit raw string">;
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
@@ -8628,10 +8628,6 @@ def aligned_alloc_unavailable : Flag<["-"], "faligned-alloc-unavailable">,
   MarshallingInfoFlag<LangOpts<"AlignedAllocationUnavailable">>,
   ShouldParseIf<faligned_allocation.KeyPath>;
 
-def finitial_counter_value_EQ : Joined<["-"], "finitial-counter-value=">,
-  HelpText<"Sets the initial value for __COUNTER__, defaults to 0.">,
-  MarshallingInfoInt<PreprocessorOpts<"InitialCounterValue">, "0">;
-
 } // let Visibility = [CC1Option]
 
 //===----------------------------------------------------------------------===//
diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
@@ -226,7 +226,7 @@ class Preprocessor {
       LangOptions::FPEvalMethodKind::FEM_UnsetOnCommandLine;
 
   // Next __COUNTER__ value, starts at 0.
-  uint32_t CounterValue = 0;
+  unsigned CounterValue = 0;
 
   enum {
     /// Maximum depth of \#includes.
@@ -2421,8 +2421,8 @@ class Preprocessor {
   bool SawDateOrTime() const {
     return DATELoc != SourceLocation() || TIMELoc != SourceLocation();
   }
-  uint32_t getCounterValue() const { return CounterValue; }
-  void setCounterValue(uint32_t V) { CounterValue = V; }
+  unsigned getCounterValue() const { return CounterValue; }
+  void setCounterValue(unsigned V) { CounterValue = V; }
 
   LangOptions::FPEvalMethodKind getCurrentFPEvalMethod() const {
     assert(CurrentFPEvalMethod != LangOptions::FEM_UnsetOnCommandLine &&
diff --git a/clang/include/clang/Lex/PreprocessorOptions.h b/clang/include/clang/Lex/PreprocessorOptions.h
@@ -198,10 +198,6 @@ class PreprocessorOptions {
   /// If set, the UNIX timestamp specified by SOURCE_DATE_EPOCH.
   std::optional<uint64_t> SourceDateEpoch;
 
-  /// The initial value for __COUNTER__; typically is zero but can be set via a
-  /// -cc1 flag for testing purposes.
-  uint32_t InitialCounterValue = 0;
-
 public:
   PreprocessorOptions() : PrecompiledPreambleBytes(0, false) {}
 
diff --git a/clang/include/clang/Serialization/ASTReader.h b/clang/include/clang/Serialization/ASTReader.h
@@ -220,8 +220,8 @@ class ASTReaderListener {
   }
 
   /// Receives __COUNTER__ value.
-  virtual void ReadCounter(const serialization::ModuleFile &M, uint32_t Value) {
-  }
+  virtual void ReadCounter(const serialization::ModuleFile &M,
+                           unsigned Value) {}
 
   /// This is called for each AST file loaded.
   virtual void visitModuleFile(StringRef Filename,
@@ -312,7 +312,7 @@ class ChainedASTReaderListener : public ASTReaderListener {
                                bool Complain,
                                std::string &SuggestedPredefines) override;
 
-  void ReadCounter(const serialization::ModuleFile &M, uint32_t Value) override;
+  void ReadCounter(const serialization::ModuleFile &M, unsigned Value) override;
   bool needsInputFileVisitation() override;
   bool needsSystemInputFileVisitation() override;
   void visitModuleFile(StringRef Filename,
@@ -352,7 +352,7 @@ class PCHValidator : public ASTReaderListener {
                                StringRef ModuleFilename,
                                StringRef SpecificModuleCachePath,
                                bool Complain) override;
-  void ReadCounter(const serialization::ModuleFile &M, uint32_t Value) override;
+  void ReadCounter(const serialization::ModuleFile &M, unsigned Value) override;
 };
 
 /// ASTReaderListenter implementation to set SuggestedPredefines of
diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
@@ -518,14 +518,14 @@ class ASTInfoCollector : public ASTReaderListener {
   LangOptions &LangOpts;
   CodeGenOptions &CodeGenOpts;
   TargetOptions &TargetOpts;
-  uint32_t &Counter;
+  unsigned &Counter;
 
 public:
   ASTInfoCollector(HeaderSearchOptions &HSOpts,
                    std::string &SpecificModuleCachePath,
                    PreprocessorOptions &PPOpts, LangOptions &LangOpts,
                    CodeGenOptions &CodeGenOpts, TargetOptions &TargetOpts,
-                   uint32_t &Counter)
+                   unsigned &Counter)
       : HSOpts(HSOpts), SpecificModuleCachePath(SpecificModuleCachePath),
         PPOpts(PPOpts), LangOpts(LangOpts), CodeGenOpts(CodeGenOpts),
         TargetOpts(TargetOpts), Counter(Counter) {}
@@ -577,7 +577,7 @@ class ASTInfoCollector : public ASTReaderListener {
   }
 
   void ReadCounter(const serialization::ModuleFile &M,
-                   uint32_t NewCounter) override {
+                   unsigned NewCounter) override {
     Counter = NewCounter;
   }
 };
diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -1545,9 +1545,6 @@ void clang::InitializePreprocessor(Preprocessor &PP,
   llvm::raw_string_ostream Predefines(PredefineBuffer);
   MacroBuilder Builder(Predefines);
 
-  // Ensure that the initial value of __COUNTER__ is hooked up.
-  PP.setCounterValue(InitOpts.InitialCounterValue);
-
   // Emit line markers for various builtin sections of the file. The 3 here
   // marks <built-in> as being a system header, which suppresses warnings when
   // the same macro is defined multiple times.
diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -1735,19 +1735,7 @@ void Preprocessor::ExpandBuiltinMacro(Token &Tok) {
       Diag(getLastFPEvalPragmaLocation(), diag::note_pragma_entered_here);
     }
   } else if (II == Ident__COUNTER__) {
-    Diag(Tok.getLocation(),
-         getLangOpts().C2y ? diag::warn_counter : diag::ext_counter);
-    // __COUNTER__ expands to a simple numeric value that must be less than
-    // 2147483647.
-    constexpr uint32_t MaxPosValue = std::numeric_limits<int32_t>::max();
-    if (CounterValue > MaxPosValue) {
-      Diag(Tok.getLocation(), diag::err_counter_overflow);
-      // Retain the maximal value so we don't issue conversion-related
-      // diagnostics by overflowing into a long long. While this does produce
-      // a duplicate value, there's no way to ignore this error so there's no
-      // translation anyway.
-      CounterValue = MaxPosValue;
-    }
+    // __COUNTER__ expands to a simple numeric value.
     OS << CounterValue++;
     Tok.setKind(tok::numeric_constant);
   } else if (II == Ident__has_feature) {
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
@@ -225,7 +225,7 @@ bool ChainedASTReaderListener::ReadPreprocessorOptions(
 }
 
 void ChainedASTReaderListener::ReadCounter(const serialization::ModuleFile &M,
-                                           uint32_t Value) {
+                                           unsigned Value) {
   First->ReadCounter(M, Value);
   Second->ReadCounter(M, Value);
 }
@@ -973,7 +973,7 @@ bool PCHValidator::ReadHeaderSearchOptions(const HeaderSearchOptions &HSOpts,
       PP.getPreprocessorOpts());
 }
 
-void PCHValidator::ReadCounter(const ModuleFile &M, uint32_t Value) {
+void PCHValidator::ReadCounter(const ModuleFile &M, unsigned Value) {
   PP.setCounterValue(Value);
 }
 
diff --git a/clang/test/C/C2y/n3457.c b/clang/test/C/C2y/n3457.c
diff --git a/clang/test/C/C2y/n3457_1.c b/clang/test/C/C2y/n3457_1.c
diff --git a/clang/test/C/C2y/n3457_2.c b/clang/test/C/C2y/n3457_2.c
diff --git a/clang/www/c_status.html b/clang/www/c_status.html
@@ -329,7 +329,7 @@ <h2 id="c2y">C2y implementation status</h2>
     <tr>
       <td>The __COUNTER__ predefined macro</td>
       <td><a href="https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3457.htm">N3457</a></td>
-      <td class="unreleased" align="center">Clang 22</td>
+      <td class="unknown" align="center">Unknown</td>
 	</tr>
     <tr>
       <td>Chasing Ghosts I: constant expressions v2</td>
diff --git a/revert_patches.txt b/revert_patches.txt
@@ -2,3 +2,6 @@
 revert: breaks rocBLAS build
 d57230c7 [AMDGPU][MC] Disallow op_sel in some VOP3P dot instructions (#100485)
 ---
+breaks build of ROCmValidationSuite
+[C2y] Support WG14 N3457, the __COUNTER__ macro (#162662)
+---
diff --git a/third-party/benchmark/include/benchmark/benchmark.h b/third-party/benchmark/include/benchmark/benchmark.h
@@ -250,19 +250,13 @@ BENCHMARK(BM_test)->Unit(benchmark::kMillisecond);
   _Pragma("GCC diagnostic push")             \
   _Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"")
 #define BENCHMARK_RESTORE_DEPRECATED_WARNING _Pragma("GCC diagnostic pop")
-#define BENCHMARK_DISABLE_PEDANTIC_WARNING \
-  _Pragma("GCC diagnostic push")             \
-  _Pragma("GCC diagnostic ignored \"-Wpedantic\"")
-#define BENCHMARK_RESTORE_PEDANTIC_WARNING _Pragma("GCC diagnostic pop")
 #elif defined(__NVCOMPILER)
 #define BENCHMARK_BUILTIN_EXPECT(x, y) __builtin_expect(x, y)
 #define BENCHMARK_DEPRECATED_MSG(msg) __attribute__((deprecated(msg)))
 #define BENCHMARK_DISABLE_DEPRECATED_WARNING \
   _Pragma("diagnostic push") \
   _Pragma("diag_suppress deprecated_entity_with_custom_message")
 #define BENCHMARK_RESTORE_DEPRECATED_WARNING _Pragma("diagnostic pop")
-#define BENCHMARK_DISABLE_PEDANTIC_WARNING
-#define BENCHMARK_RESTORE_PEDANTIC_WARNING
 #else
 #define BENCHMARK_BUILTIN_EXPECT(x, y) x
 #define BENCHMARK_DEPRECATED_MSG(msg)
@@ -271,8 +265,6 @@ BENCHMARK(BM_test)->Unit(benchmark::kMillisecond);
       __LINE__) ") : warning note: " msg))
 #define BENCHMARK_DISABLE_DEPRECATED_WARNING
 #define BENCHMARK_RESTORE_DEPRECATED_WARNING
-#define BENCHMARK_DISABLE_PEDANTIC_WARNING
-#define BENCHMARK_RESTORE_PEDANTIC_WARNING
 #endif
 // clang-format on
 
@@ -1470,13 +1462,11 @@ class Fixture : public internal::Benchmark {
 // Check that __COUNTER__ is defined and that __COUNTER__ increases by 1
 // every time it is expanded. X + 1 == X + 0 is used in case X is defined to be
 // empty. If X is empty the expression becomes (+1 == +0).
-BENCHMARK_DISABLE_PEDANTIC_WARNING
 #if defined(__COUNTER__) && (__COUNTER__ + 1 == __COUNTER__ + 0)
 #define BENCHMARK_PRIVATE_UNIQUE_ID __COUNTER__
 #else
 #define BENCHMARK_PRIVATE_UNIQUE_ID __LINE__
 #endif
-BENCHMARK_RESTORE_PEDANTIC_WARNING
 
 // Helpers for generating unique variable names
 #ifdef BENCHMARK_HAS_CXX11
