[Clang][Sema] Make UnresolvedLookupExprs in class scope explicit specializations instantiation dependent (#100392)

A class member named by an expression in a member function that may instantiate to a static _or_ non-static member is represented by a `UnresolvedLookupExpr` in order to defer the implicit transformation to a class member access expression until instantiation. Since `ASTContext::getDecltypeType` only creates a `DecltypeType` that has a `DependentDecltypeType` as its canonical type when the operand is instantiation dependent, and since we do not transform types unless they are instantiation dependent, we need to mark the `UnresolvedLookupExpr` as instantiation dependent in order to correctly build a `DecltypeType` using the expression as its operand with a `DependentDecltypeType` canonical type. Fixes #99873. 

1 files changed, 4 insertions, 2 deletions

diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 7d814e6b..b5978dd 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -17932,7 +17932,8 @@ buildDeclareReductionRef(Sema &SemaRef, SourceLocation Loc, SourceRange Range,
     return UnresolvedLookupExpr::Create(
         SemaRef.Context, /*NamingClass=*/nullptr,
         ReductionIdScopeSpec.getWithLocInContext(SemaRef.Context), ReductionId,
-        /*ADL=*/true, ResSet.begin(), ResSet.end(), /*KnownDependent=*/false);
+        /*ADL=*/true, ResSet.begin(), ResSet.end(), /*KnownDependent=*/false,
+        /*KnownInstantiationDependent=*/false);
   }
   // Lookup inside the classes.
   // C++ [over.match.oper]p3:
@@ -20798,7 +20799,8 @@ static ExprResult buildUserDefinedMapperRef(Sema &SemaRef, Scope *S,
     return UnresolvedLookupExpr::Create(
         SemaRef.Context, /*NamingClass=*/nullptr,
         MapperIdScopeSpec.getWithLocInContext(SemaRef.Context), MapperId,
-        /*ADL=*/false, URS.begin(), URS.end(), /*KnownDependent=*/false);
+        /*ADL=*/false, URS.begin(), URS.end(), /*KnownDependent=*/false,
+        /*KnownInstantiationDependent=*/false);
   }
   SourceLocation Loc = MapperId.getLoc();
   // [OpenMP 5.0], 2.19.7.3 declare mapper Directive, Restrictions