Rebase onto #105602

Created using spr 1.3.5-bogner

Author: bogner

.github/workflows/libcxx-build-and-test.yaml

@@ -146,6 +146,7 @@ jobs:
           'generic-no-experimental',
           'generic-no-filesystem',
           'generic-no-localization',
+          'generic-no-terminal',
           'generic-no-random_device',
           'generic-no-threads',
           'generic-no-tzdb',

bolt/lib/Core/BinaryFunction.cpp

@@ -2502,7 +2502,7 @@ void BinaryFunction::annotateCFIState() {
     }
   }
 
-  if (!StateStack.empty()) {
+  if (opts::Verbosity >= 1 && !StateStack.empty()) {
     BC.errs() << "BOLT-WARNING: non-empty CFI stack at the end of " << *this
               << '\n';
   }

bolt/lib/Core/BinaryFunctionProfile.cpp

@@ -336,7 +336,8 @@ void BinaryFunction::inferFallThroughCounts() {
       if (SuccBI.Count == 0) {
         SuccBI.Count = Inferred;
         SuccBI.MispredictedCount = BinaryBasicBlock::COUNT_INFERRED;
-        Succ->ExecutionCount += Inferred;
+        Succ->ExecutionCount =
+            std::max(Succ->getKnownExecutionCount(), Inferred);
       }
     }
   }

bolt/test/X86/infer-fall-throughs.s

@@ -0,0 +1,45 @@
+## Test that infer-fall-throughs would correctly infer the wrong fall-through
+## edge count in the example
+
+# RUN: llvm-mc --filetype=obj --triple x86_64-unknown-unknown %s -o %t.o
+# RUN: link_fdata %s %t.o %t.fdata
+# RUN: llvm-strip --strip-unneeded %t.o
+# RUN: %clang %cflags %t.o -o %t.exe -Wl,-q
+# RUN: llvm-bolt %t.exe -o %t.bolt \
+# RUN:         --print-estimate-edge-counts --data=%t.fdata \
+# RUN:     2>&1 | FileCheck --check-prefix=WITHOUTINFERENCE %s
+# RUN: llvm-bolt %t.exe -o %t.bolt --infer-fall-throughs \
+# RUN:         --print-estimate-edge-counts --data=%t.fdata \
+# RUN:     2>&1 | FileCheck --check-prefix=CORRECTINFERENCE %s
+
+
+# WITHOUTINFERENCE: Binary Function "main" after estimate-edge-counts
+# WITHOUTINFERENCE: {{^\.Ltmp0}}
+# WITHOUTINFERENCE: Successors: .Ltmp1 (mispreds: 0, count: 10), .LFT0 (mispreds: 0, count: 0)
+# WITHOUTINFERENCE: {{^\.LFT0}}
+# WITHOUTINFERENCE: Exec Count : 490
+
+# CORRECTINFERENCE: Binary Function "main" after estimate-edge-counts
+# CORRECTINFERENCE: {{^\.Ltmp0}}
+# CORRECTINFERENCE: Successors: .Ltmp1 (mispreds: 0, count: 10), .LFT0 (inferred count: 490)
+# CORRECTINFERENCE: {{^\.LFT0}}
+# CORRECTINFERENCE: Exec Count : 490
+
+
+        .globl  main
+        .type   main, @function
+main:
+LLmain_LLstart:
+        jmp     LLstart
+# FDATA: 1 main #LLmain_LLstart# 1 main #LLstart# 0 500
+LLstart:
+        jge     LLexit
+# FDATA: 1 main #LLstart# 1 main #LLexit# 0 10
+# FDATA: 1 main #LLstart# 1 main #LLmore# 0 0
+LLmore:
+        movl    $5, %eax
+# FDATA: 1 main #LLmore# 1 main #LLexit# 0 490
+LLexit:
+        ret
+.LLmain_end:
+        .size   main, .LLmain_end-main

clang/cmake/caches/CrossWinToARMLinux.cmake

@@ -108,9 +108,9 @@ endif()
 
 message(STATUS "Toolchain target to build: ${LLVM_TARGETS_TO_BUILD}")
 
-# Allow to override libc++ ABI version. Use 2 by default.
+# Allow to override libc++ ABI version (1 is default).
 if (NOT DEFINED LIBCXX_ABI_VERSION)
-  set(LIBCXX_ABI_VERSION 2)
+  set(LIBCXX_ABI_VERSION 1)
 endif()
 
 message(STATUS "Toolchain's Libc++ ABI version: ${LIBCXX_ABI_VERSION}")
@@ -217,6 +217,8 @@ set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_ENABLE_SHARED
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_ABI_VERSION                        ${LIBCXX_ABI_VERSION} CACHE STRING "")
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_CXX_ABI                            "libcxxabi" CACHE STRING "")    #!!!
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS      ON CACHE BOOL "")
+# Merge libc++ and libc++abi libraries into the single libc++ library file.
+set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_ENABLE_STATIC_ABI_LIBRARY          ON CACHE BOOL "")
 
 # Avoid searching for the python3 interpreter during the runtimes configuration for the cross builds.
 # It starts searching the python3 package using the target's sysroot path, that usually is not compatible with the build host.

clang/docs/InternalsManual.rst

@@ -3200,7 +3200,7 @@ are similar.
    always involve two functions: an ``ActOnXXX`` function that will be called
    directly from the parser, and a ``BuildXXX`` function that performs the
    actual semantic analysis and will (eventually!) build the AST node.  It's
-   fairly common for the ``ActOnCXX`` function to do very little (often just
+   fairly common for the ``ActOnXXX`` function to do very little (often just
    some minor translation from the parser's representation to ``Sema``'s
    representation of the same thing), but the separation is still important:
    C++ template instantiation, for example, should always call the ``BuildXXX``

clang/docs/LanguageExtensions.rst

@@ -3987,7 +3987,7 @@ ellipsis (``...``) in the function signature. Alternatively, in C23 mode or
 later, it may be the integer literal ``0`` if there is no parameter preceding
 the ellipsis. This function initializes the given ``__builtin_va_list`` object.
 It is undefined behavior to call this function on an already initialized
-``__builin_va_list`` object.
+``__builtin_va_list`` object.
 
 * ``void __builtin_va_end(__builtin_va_list list)``
 
@@ -4321,7 +4321,7 @@ an appropriate value during the emission.
 
 Note that there is no builtin matching the `llvm.coro.save` intrinsic. LLVM
 automatically will insert one if the first argument to `llvm.coro.suspend` is
-token `none`. If a user calls `__builin_suspend`, clang will insert `token none`
+token `none`. If a user calls `__builtin_suspend`, clang will insert `token none`
 as the first argument to the intrinsic.
 
 Source location builtins

clang/docs/ReleaseNotes.rst

@@ -152,6 +152,9 @@ Resolutions to C++ Defect Reports
 - ``nullptr`` is now promoted to ``void*`` when passed to a C-style variadic function.
   (`CWG722: Can nullptr be passed to an ellipsis? <https://cplusplus.github.io/CWG/issues/722.html>`_)
 
+- Allow ``void{}`` as a prvalue of type ``void``.
+  (`CWG2351: void{} <https://cplusplus.github.io/CWG/issues/2351.html>`_).
+
 C Language Changes
 ------------------
 
@@ -287,6 +290,8 @@ Bug Fixes to C++ Support
 - Clang now properly handles the order of attributes in `extern` blocks. (#GH101990).
 - Fixed an assertion failure by preventing null explicit object arguments from being deduced. (#GH102025).
 - Correctly check constraints of explicit instantiations of member functions. (#GH46029)
+- Fixed an assertion failure about a constraint of a friend function template references to a value with greater
+  template depth than the friend function template. (#GH98258)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -305,6 +310,12 @@ Miscellaneous Clang Crashes Fixed
 - Fixed a crash caused by long chains of ``sizeof`` and other similar operators
   that can be followed by a non-parenthesized expression. (#GH45061)
 
+- Fixed an crash when compiling ``#pragma STDC FP_CONTRACT DEFAULT`` with
+  ``-ffp-contract=fast-honor-pragmas``. (#GH104830)
+
+- Fixed a crash when function has more than 65536 parameters.
+  Now a diagnostic is emitted. (#GH35741)
+
 OpenACC Specific Changes
 ------------------------
 
@@ -438,6 +449,36 @@ Moved checkers
 Sanitizers
 ----------
 
+- Added the ``-fsanitize-undefined-ignore-overflow-pattern`` flag which can be
+  used to disable specific overflow-dependent code patterns. The supported
+  patterns are: ``add-overflow-test``, ``negated-unsigned-const``, and
+  ``post-decr-while``. The sanitizer instrumentation can be toggled off for all
+  available patterns by specifying ``all``. Conversely, you can disable all
+  exclusions with ``none``.
+
+  .. code-block:: c++
+
+     /// specified with ``-fsanitize-undefined-ignore-overflow-pattern=add-overflow-test``
+     int common_overflow_check_pattern(unsigned base, unsigned offset) {
+       if (base + offset < base) { /* ... */ } // The pattern of `a + b < a`, and other re-orderings, won't be instrumented
+     }
+
+     /// specified with ``-fsanitize-undefined-ignore-overflow-pattern=negated-unsigned-const``
+     void negation_overflow() {
+       unsigned long foo = -1UL; // No longer causes a negation overflow warning
+       unsigned long bar = -2UL; // and so on...
+     }
+
+     /// specified with ``-fsanitize-undefined-ignore-overflow-pattern=post-decr-while``
+     void while_post_decrement() {
+       unsigned char count = 16;
+       while (count--) { /* ... */} // No longer causes unsigned-integer-overflow sanitizer to trip
+     }
+
+  Many existing projects have a large amount of these code patterns present.
+  This new flag should allow those projects to enable integer sanitizers with
+  less noise.
+
 Python Binding Changes
 ----------------------
 - Fixed an issue that led to crashes when calling ``Type.get_exception_specification_kind``.

clang/docs/UndefinedBehaviorSanitizer.rst

@@ -293,6 +293,48 @@ To silence reports from unsigned integer overflow, you can set
 ``-fsanitize-recover=unsigned-integer-overflow``, is particularly useful for
 providing fuzzing signal without blowing up logs.
 
+Disabling instrumentation for common overflow patterns
+------------------------------------------------------
+
+There are certain overflow-dependent or overflow-prone code patterns which
+produce a lot of noise for integer overflow/truncation sanitizers. Negated
+unsigned constants, post-decrements in a while loop condition and simple
+overflow checks are accepted and pervasive code patterns. However, the signal
+received from sanitizers instrumenting these code patterns may be too noisy for
+some projects. To disable instrumentation for these common patterns one should
+use ``-fsanitize-undefined-ignore-overflow-pattern=``.
+
+Currently, this option supports three overflow-dependent code idioms:
+
+``negated-unsigned-const``
+
+.. code-block:: c++
+
+    /// -fsanitize-undefined-ignore-overflow-pattern=negated-unsigned-const
+    unsigned long foo = -1UL; // No longer causes a negation overflow warning
+    unsigned long bar = -2UL; // and so on...
+
+``post-decr-while``
+
+.. code-block:: c++
+
+    /// -fsanitize-undefined-ignore-overflow-pattern=post-decr-while
+    unsigned char count = 16;
+    while (count--) { /* ... */ } // No longer causes unsigned-integer-overflow sanitizer to trip
+
+``add-overflow-test``
+
+.. code-block:: c++
+
+    /// -fsanitize-undefined-ignore-overflow-pattern=add-overflow-test
+    if (base + offset < base) { /* ... */ } // The pattern of `a + b < a`, and other re-orderings,
+                                            // won't be instrumented (same for signed types)
+
+You can enable all exclusions with
+``-fsanitize-undefined-ignore-overflow-pattern=all`` or disable all exclusions
+with ``-fsanitize-undefined-ignore-overflow-pattern=none``. Specifying ``none``
+has precedence over other values.
+
 Issue Suppression
 =================
 

clang/include/clang/AST/Expr.h

@@ -3888,6 +3888,7 @@ class BinaryOperator : public Expr {
   /// Construct an empty binary operator.
   explicit BinaryOperator(EmptyShell Empty) : Expr(BinaryOperatorClass, Empty) {
     BinaryOperatorBits.Opc = BO_Comma;
+    BinaryOperatorBits.ExcludedOverflowPattern = false;
   }
 
 public:
@@ -4043,6 +4044,15 @@ class BinaryOperator : public Expr {
   void setHasStoredFPFeatures(bool B) { BinaryOperatorBits.HasFPFeatures = B; }
   bool hasStoredFPFeatures() const { return BinaryOperatorBits.HasFPFeatures; }
 
+  /// Set and get the bit that informs arithmetic overflow sanitizers whether
+  /// or not they should exclude certain BinaryOperators from instrumentation
+  void setExcludedOverflowPattern(bool B) {
+    BinaryOperatorBits.ExcludedOverflowPattern = B;
+  }
+  bool hasExcludedOverflowPattern() const {
+    return BinaryOperatorBits.ExcludedOverflowPattern;
+  }
+
   /// Get FPFeatures from trailing storage
   FPOptionsOverride getStoredFPFeatures() const {
     assert(hasStoredFPFeatures());

clang/include/clang/AST/ExprCXX.h

@@ -2176,8 +2176,9 @@ class LambdaExpr final : public Expr,
   const_child_range children() const;
 };
 
-/// An expression "T()" which creates a value-initialized rvalue of type
-/// T, which is a non-class type.  See (C++98 [5.2.3p2]).
+/// An expression "T()" which creates an rvalue of a non-class type T.
+/// For non-void T, the rvalue is value-initialized.
+/// See (C++98 [5.2.3p2]).
 class CXXScalarValueInitExpr : public Expr {
   friend class ASTStmtReader;
 

clang/include/clang/AST/Stmt.h

@@ -650,6 +650,11 @@ class alignas(void *) Stmt {
     LLVM_PREFERRED_TYPE(bool)
     unsigned HasFPFeatures : 1;
 
+    /// Whether or not this BinaryOperator should be excluded from integer
+    /// overflow sanitization.
+    LLVM_PREFERRED_TYPE(bool)
+    unsigned ExcludedOverflowPattern : 1;
+
     SourceLocation OpLoc;
   };
 

clang/include/clang/AST/Type.h

@@ -1929,6 +1929,11 @@ class alignas(TypeAlignment) Type : public ExtQualsTypeCommonBase {
     unsigned Kind : NumOfBuiltinTypeBits;
   };
 
+public:
+  static constexpr int FunctionTypeNumParamsWidth = 16;
+  static constexpr int FunctionTypeNumParamsLimit = (1 << 16) - 1;
+
+protected:
   /// FunctionTypeBitfields store various bits belonging to FunctionProtoType.
   /// Only common bits are stored here. Additional uncommon bits are stored
   /// in a trailing object after FunctionProtoType.
@@ -1966,7 +1971,7 @@ class alignas(TypeAlignment) Type : public ExtQualsTypeCommonBase {
     /// According to [implimits] 8 bits should be enough here but this is
     /// somewhat easy to exceed with metaprogramming and so we would like to
     /// keep NumParams as wide as reasonably possible.
-    unsigned NumParams : 16;
+    unsigned NumParams : FunctionTypeNumParamsWidth;
 
     /// The type of exception specification this function has.
     LLVM_PREFERRED_TYPE(ExceptionSpecificationType)

clang/include/clang/Basic/BuiltinsX86.def

@@ -2217,6 +2217,50 @@ TARGET_BUILTIN(__builtin_ia32_vcvttps2ibs512_mask, "V16UiV16fV16UiUsIi", "nV:512
 TARGET_BUILTIN(__builtin_ia32_vcvttps2iubs128_mask, "V4UiV4fV4UiUc", "nV:128:", "avx10.2-256")
 TARGET_BUILTIN(__builtin_ia32_vcvttps2iubs256_mask, "V8UiV8fV8UiUcIi", "nV:256:", "avx10.2-256")
 TARGET_BUILTIN(__builtin_ia32_vcvttps2iubs512_mask, "V16UiV16fV16UiUsIi", "nV:512:", "avx10.2-512")
+
+// AVX10.2 CONVERT
+TARGET_BUILTIN(__builtin_ia32_vcvt2ps2phx128_mask, "V8xV4fV4fV8xUc", "ncV:128:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvt2ps2phx256_mask, "V16xV8fV8fV16xUsIi", "ncV:256:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvt2ps2phx512_mask, "V32xV16fV16fV32xUiIi", "ncV:512:", "avx10.2-512")
+TARGET_BUILTIN(__builtin_ia32_vcvtbiasph2bf8_128_mask, "V16cV16cV8xV16cUc", "nV:128:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtbiasph2bf8_256_mask, "V16cV32cV16xV16cUs", "nV:256:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtbiasph2bf8_512_mask, "V32cV64cV32xV32cUi", "nV:512:", "avx10.2-512")
+TARGET_BUILTIN(__builtin_ia32_vcvtbiasph2bf8s_128_mask, "V16cV16cV8xV16cUc", "nV:128:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtbiasph2bf8s_256_mask, "V16cV32cV16xV16cUs", "nV:256:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtbiasph2bf8s_512_mask, "V32cV64cV32xV32cUi", "nV:512:", "avx10.2-512")
+TARGET_BUILTIN(__builtin_ia32_vcvtbiasph2hf8_128_mask, "V16cV16cV8xV16cUc", "nV:128:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtbiasph2hf8_256_mask, "V16cV32cV16xV16cUs", "nV:256:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtbiasph2hf8_512_mask, "V32cV64cV32xV32cUi", "nV:512:", "avx10.2-512")
+TARGET_BUILTIN(__builtin_ia32_vcvtbiasph2hf8s_128_mask, "V16cV16cV8xV16cUc", "nV:128:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtbiasph2hf8s_256_mask, "V16cV32cV16xV16cUs", "nV:256:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtbiasph2hf8s_512_mask, "V32cV64cV32xV32cUi", "nV:512:", "avx10.2-512")
+TARGET_BUILTIN(__builtin_ia32_vcvtne2ph2bf8_128, "V16cV8xV8x", "nV:128:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtne2ph2bf8_256, "V32cV16xV16x", "nV:256:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtne2ph2bf8_512, "V64cV32xV32x", "nV:512:", "avx10.2-512")
+TARGET_BUILTIN(__builtin_ia32_vcvtne2ph2bf8s_128, "V16cV8xV8x", "nV:128:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtne2ph2bf8s_256, "V32cV16xV16x", "nV:256:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtne2ph2bf8s_512, "V64cV32xV32x", "nV:512:", "avx10.2-512")
+TARGET_BUILTIN(__builtin_ia32_vcvtne2ph2hf8_128, "V16cV8xV8x", "nV:128:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtne2ph2hf8_256, "V32cV16xV16x", "nV:256:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtne2ph2hf8_512, "V64cV32xV32x", "nV:512:", "avx10.2-512")
+TARGET_BUILTIN(__builtin_ia32_vcvtne2ph2hf8s_128, "V16cV8xV8x", "nV:128:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtne2ph2hf8s_256, "V32cV16xV16x", "nV:256:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtne2ph2hf8s_512, "V64cV32xV32x", "nV:512:", "avx10.2-512")
+TARGET_BUILTIN(__builtin_ia32_vcvthf8_2ph128_mask, "V8xV16cV8xUc", "nV:128:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvthf8_2ph256_mask, "V16xV16cV16xUs", "nV:256:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvthf8_2ph512_mask, "V32xV32cV32xUi", "nV:512:", "avx10.2-512")
+TARGET_BUILTIN(__builtin_ia32_vcvtneph2bf8_128_mask, "V16cV8xV16cUc", "nV:128:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtneph2bf8_256_mask, "V16cV16xV16cUs", "nV:256:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtneph2bf8_512_mask, "V32cV32xV32cUi", "nV:512:", "avx10.2-512")
+TARGET_BUILTIN(__builtin_ia32_vcvtneph2bf8s_128_mask, "V16cV8xV16cUc", "nV:128:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtneph2bf8s_256_mask, "V16cV16xV16cUs", "nV:256:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtneph2bf8s_512_mask, "V32cV32xV32cUi", "nV:512:", "avx10.2-512")
+TARGET_BUILTIN(__builtin_ia32_vcvtneph2hf8_128_mask, "V16cV8xV16cUc", "nV:128:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtneph2hf8_256_mask, "V16cV16xV16cUs", "nV:256:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtneph2hf8_512_mask, "V32cV32xV32cUi", "nV:512:", "avx10.2-512")
+TARGET_BUILTIN(__builtin_ia32_vcvtneph2hf8s_128_mask, "V16cV8xV16cUc", "nV:128:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtneph2hf8s_256_mask, "V16cV16xV16cUs", "nV:256:", "avx10.2-256")
+TARGET_BUILTIN(__builtin_ia32_vcvtneph2hf8s_512_mask, "V32cV32xV32cUi", "nV:512:", "avx10.2-512")
 #undef BUILTIN
 #undef TARGET_BUILTIN
 #undef TARGET_HEADER_BUILTIN

clang/include/clang/Basic/CodeGenOptions.def

@@ -176,6 +176,7 @@ CODEGENOPT(MergeAllConstants , 1, 1) ///< Merge identical constants.
 CODEGENOPT(MergeFunctions    , 1, 0) ///< Set when -fmerge-functions is enabled.
 CODEGENOPT(NoCommon          , 1, 0) ///< Set when -fno-common or C++ is enabled.
 CODEGENOPT(NoExecStack       , 1, 0) ///< Set when -Wa,--noexecstack is enabled.
+CODEGENOPT(MipsMsa           , 1, 0) ///< Set when -Wa,-mmsa is enabled.
 CODEGENOPT(FatalWarnings     , 1, 0) ///< Set when -Wa,--fatal-warnings is
                                      ///< enabled.
 CODEGENOPT(NoWarn            , 1, 0) ///< Set when -Wa,--no-warn is enabled.

clang/include/clang/Basic/DiagnosticParseKinds.td

@@ -481,6 +481,9 @@ def ext_decomp_decl_empty : ExtWarn<
   "ISO C++17 does not allow a decomposition group to be empty">,
   InGroup<DiagGroup<"empty-decomposition">>;
 
+def err_function_parameter_limit_exceeded : Error<
+  "too many function parameters; subsequent parameters will be ignored">;
+
 // C++26 structured bindings
 def ext_decl_attrs_on_binding : ExtWarn<
   "an attribute specifier sequence attached to a structured binding declaration "