[Clang] Remove the special-casing for RequiresExprBodyDecl in BuildResolvedCallExpr() after fd87d765c0 (#111277)

The special-casing for RequiresExprBodyDecl caused a regression, as
reported in #110785.

The original fix for #84020 has been superseded by fd87d765c0, which
establishes a `DependentScopeDeclRefExpr` instead of a
`CXXDependentScopeMemberExpr` for the case in issue. So the spurious
diagnostic in #84020 would no longer occur.

This also merges the test for #84020 together with that for #110785 into
clang/test/SemaTemplate/instantiate-requires-expr.cpp.

No release note because I think this merits a backport.

Fixes #110785

(cherry picked from commit 8c1547055eaf65003f3e6fd024195f4926ff2356)

clang/lib/Sema/SemaExpr.cpp

@@ -6922,8 +6922,7 @@ ExprResult Sema::BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
   }
 
   if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(FDecl))
-    if (!isa<RequiresExprBodyDecl>(CurContext) &&
-        Method->isImplicitObjectMemberFunction())
+    if (Method->isImplicitObjectMemberFunction())
       return ExprError(Diag(LParenLoc, diag::err_member_call_without_object)
                        << Fn->getSourceRange() << 0);
 

clang/lib/Sema/TreeTransform.h

@@ -13608,7 +13608,7 @@ bool TreeTransform<Derived>::TransformOverloadExprDecls(OverloadExpr *Old,
     }
 
     AllEmptyPacks &= Decls.empty();
-  };
+  }
 
   // C++ [temp.res]/8.4.2:
   //   The program is ill-formed, no diagnostic required, if [...] lookup for

clang/test/SemaCXX/PR84020.cpp

@@ -1,23 +0,0 @@
-// RUN: %clang_cc1 -std=c++20 -verify %s
-// RUN: %clang_cc1 -std=c++23 -verify %s
-// expected-no-diagnostics
-
-struct B {
-    template <typename S>
-    void foo();
-
-    void bar();
-};
-
-template <typename T, typename S>
-struct A : T {
-    auto foo() {
-        static_assert(requires { T::template foo<S>(); });
-        static_assert(requires { T::bar(); });
-    }
-};
-
-int main() {
-    A<B, double> a;
-    a.foo();
-}

clang/test/SemaTemplate/instantiate-requires-expr.cpp

@@ -237,3 +237,34 @@ constexpr bool e_v = true;
 static_assert(e_v<bool>);
 
 } // namespace GH73885
+
+namespace GH84020 {
+
+struct B {
+  template <typename S> void foo();
+  void bar();
+};
+
+template <typename T, typename S> struct A : T {
+  void foo() {
+    static_assert(requires { T::template foo<S>(); });
+    static_assert(requires { T::bar(); });
+  }
+};
+
+template class A<B, double>;
+
+} // namespace GH84020
+
+namespace GH110785 {
+
+struct Foo {
+  static void f(auto) requires(false) {}
+  void f(int) {}
+
+  static_assert([](auto v) {
+    return requires { f(v); };
+  } (0) == false);
+};
+
+} // namespace GH110785