[clang] fix incorrect assumption about function type 's ExtInfo

This fixes an assumption that the ExtInfo for two same function types
would have referential equality.

This should compare these ExtInfos by value instead.

The bug is pre-existing to #147835,
but that PR adds another way to reproduce it.

Author: mizvekov

clang/docs/ReleaseNotes.rst

@@ -350,6 +350,9 @@ Bug Fixes to C++ Support
   authentication enabled. (#GH152601)
 - Fix the check for narrowing int-to-float conversions, so that they are detected in
   cases where converting the float back to an integer is undefined behaviour (#GH157067).
+- Fix a crash when applying binary or ternary operators to two same function types with different spellings,
+  where at least one of the function parameters has an attribute which affects
+  the function type.
 - Fix an assertion failure when a ``constexpr`` variable is only referenced through
   ``__builtin_addressof``, and related issues with builtin arguments. (#GH154034)
 

clang/lib/AST/ASTContext.cpp

@@ -14195,7 +14195,11 @@ static QualType getCommonNonSugarTypeNode(const ASTContext &Ctx, const Type *X,
     FunctionProtoType::ExtProtoInfo EPIX = FX->getExtProtoInfo(),
                                     EPIY = FY->getExtProtoInfo();
     assert(EPIX.ExtInfo == EPIY.ExtInfo);
-    assert(EPIX.ExtParameterInfos == EPIY.ExtParameterInfos);
+    assert(!EPIX.ExtParameterInfos == !EPIY.ExtParameterInfos);
+    assert(!EPIX.ExtParameterInfos ||
+           llvm::equal(
+               llvm::ArrayRef(EPIX.ExtParameterInfos, FX->getNumParams()),
+               llvm::ArrayRef(EPIY.ExtParameterInfos, FY->getNumParams())));
     assert(EPIX.RefQualifier == EPIY.RefQualifier);
     assert(EPIX.TypeQuals == EPIY.TypeQuals);
     assert(EPIX.Variadic == EPIY.Variadic);

clang/test/SemaCXX/sugar-common-types.cpp

@@ -203,3 +203,27 @@ namespace member_pointers {
   N t3 = 0 ? &W1::a : &W2::b;
   // expected-error@-1 {{rvalue of type 'B1 member_pointers::W<void>::*'}}
 } // namespace member_pointers
+
+namespace FunctionTypeExtInfo {
+  namespace RecordType {
+    class A;
+    void (*x)(__attribute__((swift_async_context)) A *);
+
+    class A;
+    void (*y)(__attribute__((swift_async_context)) A *);
+
+    N t1 = 0 ? x : y;
+    // expected-error@-1 {{lvalue of type 'void (*)(__attribute__((swift_async_context)) A *)'}}
+  } // namespace RecordType
+  namespace TypedefType {
+    class A;
+    using B = A;
+    void (*x)(__attribute__((swift_async_context)) B *);
+
+    using B = A;
+    void (*y)(__attribute__((swift_async_context)) B *);
+
+    N t1 = 0 ? x : y;
+    // expected-error@-1 {{lvalue of type 'void (*)(__attribute__((swift_async_context)) B *)'}}
+  } // namespace TypedefType
+} // namespace FunctionTypeExtInfo