draft unittest not ready

Author: maramatias

clang/docs/ReleaseNotes.rst

@@ -642,6 +642,10 @@ Improvements to Clang's diagnostics
   #GH69470, #GH59391, #GH58172, #GH46215, #GH45915, #GH45891, #GH44490,
   #GH36703, #GH32903, #GH23312, #GH69874.
 
+- Improved the performance of static assertions envolving large integers by
+  using hex format instead of string.
+
+  Fixes #GH71675
 
 Improvements to Clang's time-trace
 ----------------------------------

clang/lib/Sema/SemaDeclCXX.cpp

@@ -47,6 +47,7 @@
 #include "clang/Sema/SemaOpenMP.h"
 #include "clang/Sema/Template.h"
 #include "clang/Sema/TemplateDeduction.h"
+#include "llvm/ADT/APSInt.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringExtras.h"
@@ -17575,7 +17576,14 @@ static bool ConvertAPValueToString(const APValue &V, QualType T,
           break;
         }
       }
-      V.getInt().toString(Str);
+
+      llvm::APSInt vInt = V.getInt();
+      if (vInt > std::numeric_limits<uint64_t>::max() ||
+          vInt < std::numeric_limits<int64_t>::min()) {
+            vInt.toString(Str,16);
+      } else {
+        vInt.toString(Str);
+      }
     }
 
     break;

clang/test/CXX/dcl.decl/dcl.decl.general/p4-20.cpp

@@ -35,6 +35,11 @@ struct S {
   void member() requires(sizeof(T) > 1);
 };
 
+namespace GH71675 {
+  constexpr unsigned _BitInt(__BITINT_MAXWIDTH__ >> 6) F = ~0;
+  static_assert(F == 1); // no-error
+}
+
 template<typename T>
 void ContainingFunction() {
   // expected-error@+1 {{non-templated function cannot have a requires clause}}