[clang] Revert "[Clang][Sema] Fix crash when using name of UnresolvedUsingValueDecl with template arguments (#83842)" (PR #84457)

[Krystian Stasiowski via cfe-commits]

https://github.com/sdkrystian created https://github.com/llvm/llvm-project/pull/84457

This reverts commit a642eb89bdaf10c6b4994fc1187de27b441236ed.

>From 02f98e180b94bec0c6abafeaaf8a7513f5116eab Mon Sep 17 00:00:00 2001
From: Krystian Stasiowski <sdkrystian at gmail.com>
Date: Fri, 8 Mar 2024 05:44:48 -0500
Subject: [PATCH] Revert "[Clang][Sema] Fix crash when using name of
 UnresolvedUsingValueDecl with template arguments (#83842)"

This reverts commit a642eb89bdaf10c6b4994fc1187de27b441236ed.
---
 clang/docs/ReleaseNotes.rst                   |  2 --
 clang/lib/Sema/SemaDecl.cpp                   |  5 +---
 clang/lib/Sema/SemaTemplate.cpp               | 10 +++----
 .../unqual-unresolved-using-value.cpp         | 30 -------------------
 4 files changed, 5 insertions(+), 42 deletions(-)
 delete mode 100644 clang/test/SemaTemplate/unqual-unresolved-using-value.cpp

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 225ca85e18115d..0ee2801766a9cc 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -332,8 +332,6 @@ Bug Fixes to C++ Support
   our attention by an attempt to fix in (#GH77703). Fixes (#GH83385).
 - Fix evaluation of some immediate calls in default arguments.
   Fixes (#GH80630)
-- Fix a crash when an explicit template argument list is used with a name for which lookup
-  finds a non-template function and a dependent using declarator.
 - Fixed an issue where the ``RequiresExprBody`` was involved in the lambda dependency
   calculation. (#GH56556), (#GH82849).
 - Fix a bug where overload resolution falsely reported an ambiguity when it was comparing
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 910d0dfbf9f65f..1f4a041e88dfff 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -1110,9 +1110,7 @@ Sema::NameClassification Sema::ClassifyName(Scope *S, CXXScopeSpec &SS,
     //   unqualified-id followed by a < and name lookup finds either one
     //   or more functions or finds nothing.
     if (!IsFilteredTemplateName)
-      FilterAcceptableTemplateNames(Result,
-                                    /*AllowFunctionTemplates=*/true,
-                                    /*AllowDependent=*/true);
+      FilterAcceptableTemplateNames(Result);
 
     bool IsFunctionTemplate;
     bool IsVarTemplate;
@@ -1122,7 +1120,6 @@ Sema::NameClassification Sema::ClassifyName(Scope *S, CXXScopeSpec &SS,
       Template = Context.getOverloadedTemplateName(Result.begin(),
                                                    Result.end());
     } else if (!Result.empty()) {
-      assert(!Result.isUnresolvableResult());
       auto *TD = cast<TemplateDecl>(getAsTemplateNameDecl(
           *Result.begin(), /*AllowFunctionTemplates=*/true,
           /*AllowDependent=*/false));
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 7e91815c2d52a8..83eee83aa6cad8 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -491,20 +491,18 @@ bool Sema::LookupTemplateName(LookupResult &Found,
     // To keep our behavior consistent, we apply the "finds nothing" part in
     // all language modes, and diagnose the empty lookup in ActOnCallExpr if we
     // successfully form a call to an undeclared template-id.
-    bool AnyFunctions =
-        getLangOpts().CPlusPlus20 && llvm::any_of(Found, [](NamedDecl *ND) {
+    bool AllFunctions =
+        getLangOpts().CPlusPlus20 && llvm::all_of(Found, [](NamedDecl *ND) {
           return isa<FunctionDecl>(ND->getUnderlyingDecl());
         });
-    if (AnyFunctions || (Found.empty() && !IsDependent)) {
+    if (AllFunctions || (Found.empty() && !IsDependent)) {
       // If lookup found any functions, or if this is a name that can only be
       // used for a function, then strongly assume this is a function
       // template-id.
       *ATK = (Found.empty() && Found.getLookupName().isIdentifier())
                  ? AssumedTemplateKind::FoundNothing
                  : AssumedTemplateKind::FoundFunctions;
-      FilterAcceptableTemplateNames(Found,
-                                    /*AllowFunctionTemplates*/ true,
-                                    /*AllowDependent*/ true);
+      Found.clear();
       return false;
     }
   }
diff --git a/clang/test/SemaTemplate/unqual-unresolved-using-value.cpp b/clang/test/SemaTemplate/unqual-unresolved-using-value.cpp
deleted file mode 100644
index 688e7a0a10b779..00000000000000
--- a/clang/test/SemaTemplate/unqual-unresolved-using-value.cpp
+++ /dev/null
@@ -1,30 +0,0 @@
-// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %s
-
-template<typename T>
-struct A : T {
-  using T::f;
-  using T::g;
-  using T::h;
-
-  void f();
-  void g();
-
-  void i() {
-    f<int>();
-    g<int>(); // expected-error{{no member named 'g' in 'A<B>'}}
-    h<int>(); // expected-error{{expected '(' for function-style cast or type construction}}
-              // expected-error at -1{{expected expression}}
-  }
-};
-
-struct B {
-  template<typename T>
-  void f();
-
-  void g();
-
-  template<typename T>
-  void h();
-};
-
-template struct A<B>; // expected-note{{in instantiation of member function 'A<B>::i' requested here}}