[PATCH] D53847: [C++2a] P0634r3: Down with typename!

[Alan Zhao via Phabricator via cfe-commits]

ayzhao added inline comments.


================
Comment at: clang/lib/Sema/SemaDecl.cpp:362
+        // allow this as an extension.
+        if (AllowImplicitTypename == ImplicitTypenameContext::No &&
+            !isClassName && !IsCtorOrDtorName)
----------------
ayzhao wrote:
> Status update:
> 
> This line is currently causing [p2-2.cpp](https://github.com/llvm/llvm-project/blob/main/clang/test/CXX/module/module.interface/p2-2.cpp) to fail with the following error:
> 
> ```
> FAIL: Clang :: CXX/module/module.interface/p2-2.cpp (2 of 17555)
> ******************** TEST 'Clang :: CXX/module/module.interface/p2-2.cpp' FAILED ********************
> Script:
> --
> : 'RUN: at line 3';   /dev/shm/ayzhao_llvm/llvm-project/build/bin/clang -cc1 -internal-isystem /dev/shm/ayzhao_llvm/llvm-project/build/lib/clang/16.0.0/include -nostdsysteminc -std=c++20 /dev/shm/ayzhao_llvm/llvm-project/clang/test/CXX/module/module.interface/p2-2.cpp -verify
> --
> Exit Code: 1
>  
> Command Output (stderr):
> --
> error: 'error' diagnostics expected but not seen:
>   File /dev/shm/ayzhao_llvm/llvm-project/clang/test/CXX/module/module.interface/p2-2.cpp Line 17: cannot export 'iterator' as it is not at namespace scope
>   File /dev/shm/ayzhao_llvm/llvm-project/clang/test/CXX/module/module.interface/p2-2.cpp Line 35: cannot export 'iterator' as it is not at namespace scope
> error: 'error' diagnostics seen but not expected:
>   File /dev/shm/ayzhao_llvm/llvm-project/clang/test/CXX/module/module.interface/p2-2.cpp Line 17: declaration does not declare anything
>   File /dev/shm/ayzhao_llvm/llvm-project/clang/test/CXX/module/module.interface/p2-2.cpp Line 35: declaration does not declare anything
> 4 errors generated.
>  
> --
>  
> ********************
> ```
> 
> A reduced repro is here:
> 
> ```
> export module X;
> 
> export template <typename T>
> struct X {
>   struct iterator {
>     T node;
>   };
> };
> 
> export template <typename T> X<T>::iterator;
> ```
> 
> `Sema::getTypeName(...)` is called from [these lines](https://github.com/llvm/llvm-project/blob/ace05124f5494173ae4769259d49f33d75d6f76b/clang/lib/Parse/ParseDecl.cpp#L3391-L3396), with the result being that `TypeRep` is null in main but not null in this patch.
> 
> I'm still in the process of trying to figure out how to resolve this, but any suggestions/insights would be **very** welcome.
I fixed this with the following diff:

```
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 1375431d8998..dacba4d18021 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -362,6 +362,11 @@ ParsedType Sema::getTypeName(const IdentifierInfo &II, SourceLocation NameLoc,
         if (AllowImplicitTypename == ImplicitTypenameContext::No &&
             !isClassName && !IsCtorOrDtorName)
           return nullptr;
+        // FIXME: This hack is required in order to make the test
+        // CXX/module/module.interface/p2-2.cpp pass. Can we get this working
+        // with this method returning a non-null ParsedType?
+        if (isa<ExportDecl>(CurContext))
+          return nullptr;
         bool IsImplicitTypename = !isClassName && !IsCtorOrDtorName;
         if (IsImplicitTypename) {
           SourceLocation QualifiedLoc = SS->getRange().getBegin();
```

It's very hacky, but it works (for now)


Repository:
  rG LLVM Github Monorepo

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https://reviews.llvm.org/D53847