[clang] 55d5ba9 - [NFC] Fix compilation in C++20 mode with GCC 12

[Ilya Biryukov via cfe-commits]

Author: Ilya Biryukov
Date: 2024-01-03T17:02:00+01:00
New Revision: 55d5ba905da0db55282dd3985761ddf3dd452fd1

URL: https://github.com/llvm/llvm-project/commit/55d5ba905da0db55282dd3985761ddf3dd452fd1
DIFF: https://github.com/llvm/llvm-project/commit/55d5ba905da0db55282dd3985761ddf3dd452fd1.diff

LOG: [NFC] Fix compilation in C++20 mode with GCC 12

I ran into the following compiler error when trying to build with GCC 12
and `-DCMAKE_CXX_STANDARD=20`:
```
llvm-project/clang/lib/Sema/SemaChecking.cpp:16690:16:   required from here
/usr/include/c++/12/type_traits:971:30: error: default member initializer for '{anonymous}::SequenceChecker::Usage::UsageExpr' required before the end of its enclosing class
```

The error seems correct, GCC just instantiates the `SmallDenseMap`
early and detects it. Clang does not, but that's an acceptable
implementation difference as far as the standard is concerned.

Move constructor outside the class to avoid this problem.

Added: 
    

Modified: 
    clang/lib/Sema/SemaChecking.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index da0570b7b0f1e6..3168d38dd66c36 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -16677,7 +16677,7 @@ class SequenceChecker : public ConstEvaluatedExprVisitor<SequenceChecker> {
     /// Have we issued a diagnostic for this object already?
     bool Diagnosed = false;
 
-    UsageInfo() = default;
+    UsageInfo();
   };
   using UsageInfoMap = llvm::SmallDenseMap<Object, UsageInfo, 16>;
 
@@ -17436,6 +17436,8 @@ class SequenceChecker : public ConstEvaluatedExprVisitor<SequenceChecker> {
   }
 };
 
+SequenceChecker::UsageInfo::UsageInfo() = default;
+
 } // namespace
 
 void Sema::CheckUnsequencedOperations(const Expr *E) {