[clang] Fix a crash with parenthesized aggregate initialization and base classes

[ayzhao]

Summary

When calling InitializeBase(...), TryOrBuidlParenListInit(...) needs to
pass in the parent entity; otherwise, we erroneously try to cast
CurContext to a CXXConstructorDecl[0], which can't be done since we're
performing aggregate initialization, not constructor initialization.

Field initialization is not affected, but this patch still adds some
tests for it.

Fixes 62296

[0]: https://github.com/llvm/llvm-project/blob/33d6bd1c667456f7f4a9d338a7996a30a3af50a3/clang/lib/Sema/SemaAccess.cpp#L1696

[aaron.ballman]

LGTM, good catch! I think you should add a release note for this when landing, and this seems pretty reasonable to consider backporting to 16.x, WDYT?

[ayzhao]

add release note

[ayzhao]

In D149301#4302621, @aaron.ballman wrote:

I think you should add a release note for this when landing,

Done

and this seems pretty reasonable to consider backporting to 16.x, WDYT?

Agreed, given that this is a crash.

clang/docs/ReleaseNotes.rst

 - Fix crash when member function contains invalid default argument.
   (`#62122 <https://github.com/llvm/llvm-project/issues/62122>`_)
 - Fix crash when handling undefined template partial specialization
   (`#61356 <https://github.com/llvm/llvm-project/issues/61356>`_)
 - Fix a crash caused by incorrectly evaluating constraints on an inheriting
   constructor declaration.
   (`#62361 <https://github.com/llvm/llvm-project/issues/62361>`_)
   (`#62362 <https://github.com/llvm/llvm-project/issues/62362>`_)
+- Fix crash when attempting to perform parenthesized initialization of an
+  aggregate with a base class with only non-public constructors.
+  (`#62296 <https://github.com/llvm/llvm-project/issues/62296 >`_)
 
 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

if (ArrayLength >= Args.size()) {
 
       ResultType = S.Context.getConstantArrayType(
           AT->getElementType(), llvm::APInt(/*numBits=*/32, ArrayLength),
           nullptr, ArrayType::Normal, 0);
     }
   } else if (auto *RT = Entity.getType()->getAs<RecordType>()) {
     const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
 
-    auto BaseRange = map_range(RD->bases(), [&S](auto &base) {
-      return InitializedEntity::InitializeBase(S.getASTContext(), &base, false);
+    auto BaseRange = map_range(RD->bases(), [&](auto &base) {
+      return InitializedEntity::InitializeBase(S.getASTContext(), &base, false,
+                                               &Entity);
     });
     auto FieldRange = map_range(RD->fields(), [](auto *field) {
       return InitializedEntity::InitializeMember(field);
     });
 
     if (!ProcessEntities(BaseRange))
       return;
 

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

void bar() {
 
   V v2(v1);
   // expected-error@-1 {{call to implicitly-deleted copy constructor of 'V'}}
 
   V v3((V&&) v1);
   // expected-error@-1 {{call to implicitly-deleted copy constructor of 'V'}}
 }
 }
+
+namespace gh62296 {
+struct L {
+protected:
+  L(int);
+  // expected-note@-1 2{{declared protected here}}
+};
+
+struct M : L {};
+
+struct N {
+  L l;
+};
+
+M m(42);
+// expected-error@-1 {{base class 'L' has protected constructor}}
+// beforecxx20-warning@-2 {{aggregate initialization of type 'M' from a parenthesized list of values is a C++20 extension}}
+
+N n(43);
+// expected-error@-1 {{field of type 'L' has protected constructor}}
+// beforecxx20-warning@-2 {{aggregate initialization of type 'N' from a parenthesized list of values is a C++20 extension}}
+
+}