[flang-commits] [clang] [flang] Fix/172072 auto function param (PR #172092)

[via flang-commits]

Serafean wrote:

Sorry, this doesn't seem to work... when the parameters are visited like so:
```
  auto kind = clang_getCursorKind(current_cursor);
  if (kind == CXCursor_ParmDecl){
        auto type = clang_getCursorType(current_cursor);
        std::cout << "Param : \n\ttype:" << type << "  kind: " << type.kind <<   std::endl;

    }
```

the TypeKind in still `unexposed`.  

`AutoTypeLoc` isn't called for the auto parameter, that honor goes to `VisitFunctionTypeLoc` explicitly calling `Visit()` for every param, and then `VisitTemplateTypeParmTypeLoc` for the `auto` keyword.

for the `CXType_Auto` not being reported, so far I managed to paper over it this way:

```
--- a/clang/tools/libclang/CXType.cpp
+++ b/clang/tools/libclang/CXType.cpp
@@ -149,6 +149,16 @@ CXType cxtype::MakeCXType(QualType T, CXTranslationUnit TU) {
     if (auto *PTT = T->getAs<ParenType>()) {
       return MakeCXType(PTT->getInnerType(), TU);
     }
+    
+    // auto in function parameters
+    if(auto *TTP = T->getAs<TemplateTypeParmType>()) {
+      auto *D = TTP->getDecl();
+      if (D && D->isImplicit()) {
+        if (auto *TC = D->getTypeConstraint(); !TC) {
+          TK = CXType_Auto;
+        }
+      }
+    }
```

Logic taken from[ `TypePrinter.cpp:1676`](https://github.com/llvm/llvm-project/blob/main/clang/lib/AST/TypePrinter.cpp#L1676).

No idea yet how to stop visiting and exposing the `auto` keyword as a Cursor. 

https://github.com/llvm/llvm-project/pull/172092