[clang] Fix missing template arguments in AST of access to member variable template

[mizvekov]

Summary

Signed-off-by: Matheus Izvekov <[e-mail]>

Depends on D132816

clang/docs/ReleaseNotes.rst

- Fix `-Wpre-c++17-compat` crashing Clang when compiling C++20 code which
   `Issue 57793 <https://github.com/llvm/llvm-project/issues/57793>`_
 - Respect constructor constraints during class template argument deduction (CTAD).
   This is the suggested resolution to CWG DR2628.
   `Issue 57646 <https://github.com/llvm/llvm-project/issues/57646>`_
   `Issue 43829 <https://github.com/llvm/llvm-project/issues/43829>`_
 - Fixed a crash in C++20 mode in Clang and Clangd when compile source
   with compilation errors.
   `Issue 53628 <https://github.com/llvm/llvm-project/issues/53628>`_
+- The template arguments of a variable template being accessed as a
+  member will now be represented in the AST.
 
 
 Improvements to Clang's diagnostics
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 - Clang will now check compile-time determinable string literals as format strings.
   Fixes `Issue 55805: <https://github.com/llvm/llvm-project/issues/55805>`_.
 - ``-Wformat`` now recognizes ``%b`` for the ``printf``/``scanf`` family of
   functions and ``%B`` for the ``printf`` family of functions. Fixes

clang/lib/Sema/SemaExprMember.cpp

if (!VDecl.get())
       return ActOnDependentMemberExpr(
           BaseExpr, BaseExpr->getType(), IsArrow, OpLoc, SS, TemplateKWLoc,
           FirstQualifierInScope, MemberNameInfo, TemplateArgs);
 
     VarDecl *Var = cast<VarDecl>(VDecl.get());
     if (!Var->getTemplateSpecializationKind())
       Var->setTemplateSpecializationKind(TSK_ImplicitInstantiation, MemberLoc);
 
-    return BuildMemberExpr(
-        BaseExpr, IsArrow, OpLoc, &SS, TemplateKWLoc, Var, FoundDecl,
-        /*HadMultipleCandidates=*/false, MemberNameInfo,
-        Var->getType().getNonReferenceType(), VK_LValue, OK_Ordinary);
+    return BuildMemberExpr(BaseExpr, IsArrow, OpLoc, &SS, TemplateKWLoc, Var,
+                           FoundDecl, /*HadMultipleCandidates=*/false,
+                           MemberNameInfo, Var->getType().getNonReferenceType(),
+                           VK_LValue, OK_Ordinary, TemplateArgs);
   }
 
   // We found something that we didn't expect. Complain.
   if (isa<TypeDecl>(MemberDecl))
     Diag(MemberLoc, diag::err_typecheck_member_reference_type)
       << MemberName << BaseType << int(IsArrow);
   else
     Diag(MemberLoc, diag::err_typecheck_member_reference_unknown)

clang/test/SemaCXX/cxx1z-ast-print.cpp

 //RUN: %clang_cc1 -std=c++1z -verify -ast-print %s | FileCheck %s
 
 struct TypeSuffix {
   template <long> static int x; // expected-note {{forward declaration of template entity is here}}
   template <auto> static int y; // expected-note {{forward declaration of template entity is here}}
 };
-// CHECK: int k = TypeSuffix().x + TypeSuffix().y;
+// CHECK: int k = TypeSuffix().x<0L> + TypeSuffix().y<0L>;
 int k = TypeSuffix().x<0L> + TypeSuffix().y<0L>; // expected-warning {{instantiation of variable 'TypeSuffix::x<0>' required here, but no definition is available}} \
                                                  // expected-note {{add an explicit instantiation declaration to suppress this warning if 'TypeSuffix::x<0>' is explicitly instantiated in another translation unit}} \
                                                  // expected-warning {{instantiation of variable 'TypeSuffix::y<0L>' required here, but no definition is available}} \
                                                  // expected-note {{add an explicit instantiation declaration to suppress this warning if 'TypeSuffix::y<0L>' is explicitly instantiated in another translation unit}}

clang/unittests/Tooling/Syntax/BuildTreeTest.cpp

if (!GetParam().isCXX14OrLater()) {
     return;
   }
   EXPECT_TRUE(treeDumpEqualOnAnnotations(
       R"cpp(
 struct S {
   template<typename T>
   static constexpr T x = 42;
 };
-// FIXME: `<int>` should be a child of `MemberExpression` and `;` of
-// `ExpressionStatement`. This is a bug in clang, in `getSourceRange` methods.
 void test(S s) [[{
   s.x<int>;
 }]]
 )cpp",
       {R"txt(
 CompoundStatement
 |-'{' OpenParen
 |-ExpressionStatement Statement
-| `-MemberExpression Expression
-|   |-IdExpression Object
-|   | `-UnqualifiedId UnqualifiedId
-|   |   `-'s'
-|   |-'.' AccessToken
-|   `-IdExpression Member
-|     `-UnqualifiedId UnqualifiedId
-|       `-'x'
-|-'<'
-|-'int'
-|-'>'
-|-';'
+| |-MemberExpression Expression
+| | |-IdExpression Object
+| | | `-UnqualifiedId UnqualifiedId
+| | |   `-'s'
+| | |-'.' AccessToken
+| | `-IdExpression Member
+| |   `-UnqualifiedId UnqualifiedId
+| |     |-'x'
+| |     |-'<'
+| |     |-'int'
+| |     `-'>'
+| `-';'
 `-'}' CloseParen
 )txt"}));
 }
 
 TEST_P(BuildSyntaxTreeTest, MemberExpression_FunctionTemplate) {
   if (!GetParam().isCXX()) {
     return;
   }