[PATCH] D82805: [clang] Fix a crash on passing C structure of incompatible type to function with reference parameter

[Bruno Ricci via Phabricator via cfe-commits]

riccibruno added inline comments.


================
Comment at: clang/lib/Sema/SemaInit.cpp:4539
+    if (CXXRecordDecl *T2RecordDecl =
+        dyn_cast<CXXRecordDecl>(T2RecordType->getDecl())) {
+      const auto &Conversions = T2RecordDecl->getVisibleConversionFunctions();
----------------
ArcsinX wrote:
> riccibruno wrote:
> > I cannot reproduce this with the provided test case. Can you explain why `T2RecordDecl` would not be a `CXXRecordDecl` since we should only get there with c++?
> You can reproduce it with
> ```
> bin/clang -xc --target=arm-unknown-gnu -c ../clang/test/Sema/init-ref-c.c
> ```
> 
> We can get there with C in case of using builtins declared as functions with reference parameters (e.g. `__builtin_va_end()`)
Okay I see it now. Thank you.

I think it would be better to only call `TryRefInitWithConversionFunction` in C++ mode since conversion functions don't exist in C (only the first call on line 4773).


================
Comment at: clang/lib/Sema/SemaInit.cpp:4706
                                            Qualifiers T2Quals,
                                            InitializationSequence &Sequence) {
   QualType DestType = Entity.getType();
----------------
Can you add a comment here explaining that we can get there in C with some builtins?


================
Comment at: clang/lib/Sema/SemaInit.cpp:4773
     if (RefRelationship == Sema::Ref_Incompatible && T2->isRecordType() &&
         (isLValueRef || InitCategory.isRValue())) {
       ConvOvlResult = TryRefInitWithConversionFunction(
----------------
Here


================
Comment at: clang/test/Sema/init-ref-c.c:8
+}
\ No newline at end of file

----------------
I think it would be better to name this test `varargs-arm.c` since this bug can only happen with the varargs-related builtins (`__builtin_addressof` takes a reference but has custom type-checking).

Additional test case:
```
const __builtin_va_list cva;
__builtin_va_end(cva); // expected-error {{binding reference of type '__builtin_va_list' to value of type 'const __builtin_va_list' drops 'const' qualifier}}
```


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D82805/new/

https://reviews.llvm.org/D82805