[clang] Fix crash when passing a braced-init list to a parentehsized aggregate init expression

[ayzhao]

Summary

The previous code incorrectly assumed that we would never call
warnBracedScalarInit(...) with a EK_ParenAggInitMember. This patch fixes
the bug by warning when a scalar member is initialized via a braced-init
list when performing a parentehsized aggregate initialization. This
behavior is consistent with parentehsized list aggregate initialization.

Fixes #63008

[shafik]

Thank you for the quick fix! LGTM

[ayzhao]

rebase to see if this fixes CI

[ayzhao]

rebasing, CI seems to be fixed now

clang/docs/ReleaseNotes.rst

- Match GCC's behavior for ``__builtin_object_size`` and
   ``__builtin_dynamic_object_size`` on structs containing flexible array
   members.
   (`#62789 <https://github.com/llvm/llvm-project/issues/62789>`_).
 - Fix a crash when instantiating a non-type template argument in a dependent scope.
   (`#62533 <https://github.com/llvm/llvm-project/issues/62533>`_).
 - Fix crash when diagnosing default comparison method.
   (`#62791 <https://github.com/llvm/llvm-project/issues/62791>`_) and
   (`#62102 <https://github.com/llvm/llvm-project/issues/62102>`_).
+- Fix crash when passing a braced initializer list to a parentehsized aggregate
+  initialization expression.
+  (`#63008 <https://github.com/llvm/llvm-project/issues/63008>`_).
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 Bug Fixes to Attribute Support
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 - Fixed a bug where attribute annotations on type specifiers (enums, classes,
   structs, unions, and scoped enums) were not properly ignored, resulting in

clang/lib/Sema/SemaInit.cpp

static void warnBracedScalarInit(Sema &S, const InitializedEntity &Entity,
   switch (Entity.getKind()) {
   case InitializedEntity::EK_VectorElement:
   case InitializedEntity::EK_ComplexElement:
   case InitializedEntity::EK_ArrayElement:
   case InitializedEntity::EK_Parameter:
   case InitializedEntity::EK_Parameter_CF_Audited:
   case InitializedEntity::EK_TemplateParameter:
   case InitializedEntity::EK_Result:
+  case InitializedEntity::EK_ParenAggInitMember:
     // Extra braces here are suspicious.
     DiagID = diag::warn_braces_around_init;
     break;
 
   case InitializedEntity::EK_Member:
     // Warn on aggregate initialization but not on ctor init list or
     // default member initializer.
     if (Entity.getParent())
static void warnBracedScalarInit(Sema &S, const InitializedEntity &Entity,
 
   case InitializedEntity::EK_Exception:
   case InitializedEntity::EK_Base:
   case InitializedEntity::EK_Delegating:
   case InitializedEntity::EK_BlockElement:
   case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
   case InitializedEntity::EK_Binding:
   case InitializedEntity::EK_StmtExprResult:
-  case InitializedEntity::EK_ParenAggInitMember:
     llvm_unreachable("unexpected braced scalar init");
   }
 
   if (DiagID) {
     S.Diag(Braces.getBegin(), DiagID)
         << Entity.getType()->isSizelessBuiltinType() << Braces
         << FixItHint::CreateRemoval(Braces.getBegin())
         << FixItHint::CreateRemoval(Braces.getEnd());

clang/test/SemaCXX/paren-list-agg-init.cpp

 // beforecxx20-warning@-1 {{aggregate initialization of type 'O' from a parenthesized list of values is a C++20 extension}}
 
 O o2(0, 0); // no-error
 // beforecxx20-warning@-1 {{aggregate initialization of type 'O' from a parenthesized list of values is a C++20 extension}}
 
 O o3(0);
 // expected-error@-1 {{reference member of type 'int &&' uninitialized}}
 }
+
+namespace gh63008 {
+auto a = new A('a', {1.1});
+// expected-warning@-1 {{braces around scalar init}}
+// beforecxx20-warning@-2 {{aggregate initialization of type 'A' from a parenthesized list of values is a C++20 extension}}
+}