[clang] Skip defaulted functions in zero-as-null-pointer-constant.

The zero-as-null-pointer-constant check should not fire if it is inside
a defaulted function, e.g. defaulted spaceship operators.
Add C++20 tests with spaceship operators.

Fixes #50221

Differential Revision: https://reviews.llvm.org/D138727

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index c229a77..ad53e87 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -597,6 +597,12 @@ void Sema::diagnoseZeroToNullptrConversion(CastKind Kind, const Expr *E) {
           CodeSynthesisContext::RewritingOperatorAsSpaceship)
     return;
 
+  // Ignore null pointers in defaulted comparison operators.
+  FunctionDecl *FD = getCurFunctionDecl();
+  if (FD && FD->isDefaulted()) {
+    return;
+  }
+
   // If it is a macro from system header, and if the macro name is not "NULL",
   // do not warn.
   SourceLocation MaybeMacroLoc = E->getBeginLoc();