[libcxx-commits] [PATCH] D127695: WIP: clang: Implement Template Specialization Resugaring

[David Rector via Phabricator via libcxx-commits]

davrec added inline comments.


================
Comment at: clang/lib/Sema/SemaTemplate.cpp:534-540
+  QualType TransformSubstTemplateTypeParmType(TypeLocBuilder &TLB,
+                                              SubstTemplateTypeParmTypeLoc TL) {
+    QualType QT = TL.getType();
+    const SubstTemplateTypeParmType *T = TL.getTypePtr();
+    Decl *ReplacedDecl = T->getReplacedDecl();
+
+    Optional<unsigned> PackIndex = T->getPackIndex();
----------------
Haven't thought this through fully, but: would the following make D128113 (storing the pack index in the STTPT or introducing a new sugar type) unnecessary?
```
map<pair<Decl *, unsigned>, Optional<unsigned>> CurPackIndices;
QualType TransformSubstTemplateTypeParmType(TypeLocBuilder &TLB,
                                              SubstTemplateTypeParmTypeLoc TL) {
   QualType QT = TL.getType();
   const SubstTemplateTypeParmType *T = TL.getTypePtr();
   Decl *ReplacedDecl = T->getReplacedDecl();
   
   Optional<unsigned> &PackIndex = CurPackIndices[{ReplacedDecl, T->getIndex()}];
   if (!PackIndex && T->getReplacedParameter()->isParameterPack())
     PackIndex = 0;
    
   ...

   if (PackIndex)
     ++PackIndex;
     // ^ maybe reset to zero if > pack size, if we might be resugaring multiple expansions
   return QT;
}
```


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D127695/new/

https://reviews.llvm.org/D127695