From 9a4b574dd6a07d6811356529ebb8a3f15d6e40a2 Mon Sep 17 00:00:00 2001
From: Stephen Kelly <steveire@gmail.com>
Date: Tue, 29 Dec 2020 13:18:57 +0000
Subject: [PATCH] [clang-itdy] Simplify virtual near-miss check

Diagnose the problem in templates in the context of the template
declaration instead of in the context of all of the (possibly very many)
template instantiations.

Differential Revision: https://reviews.llvm.org/D96224
---
 .../clang-tidy/bugprone/VirtualNearMissCheck.cpp   | 31 ++++++++++++----------
 .../clang-tidy/bugprone/VirtualNearMissCheck.h     |  3 +++
 .../checkers/bugprone-virtual-near-miss.cpp        |  5 ++--
 3 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/bugprone/VirtualNearMissCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/VirtualNearMissCheck.cpp
index 150b517..dc810c6 100644
--- a/clang-tools-extra/clang-tidy/bugprone/VirtualNearMissCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/VirtualNearMissCheck.cpp
@@ -216,10 +216,9 @@ bool VirtualNearMissCheck::isOverriddenByDerivedClass(
 
 void VirtualNearMissCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
-      cxxMethodDecl(
-          unless(anyOf(isOverride(), isImplicit(), cxxConstructorDecl(),
-                       cxxDestructorDecl(), cxxConversionDecl(), isStatic(),
-                       isOverloadedOperator())))
+      cxxMethodDecl(unless(anyOf(isOverride(), cxxConstructorDecl(),
+                                 cxxDestructorDecl(), cxxConversionDecl(),
+                                 isStatic(), isOverloadedOperator())))
           .bind("method"),
       this);
 }
@@ -234,7 +233,15 @@ void VirtualNearMissCheck::check(const MatchFinder::MatchResult &Result) {
   assert(DerivedRD);
 
   for (const auto &BaseSpec : DerivedRD->bases()) {
-    if (const auto *BaseRD = BaseSpec.getType()->getAsCXXRecordDecl()) {
+    const auto *BaseRD = BaseSpec.getType()->getAsCXXRecordDecl();
+    if (const auto *TST =
+            dyn_cast<TemplateSpecializationType>(BaseSpec.getType())) {
+      auto TN = TST->getTemplateName();
+      BaseRD =
+          dyn_cast<CXXRecordDecl>(TN.getAsTemplateDecl()->getTemplatedDecl());
+    }
+
+    if (BaseRD) {
       for (const auto *BaseMD : BaseRD->methods()) {
         if (!isPossibleToBeOverridden(BaseMD))
           continue;
@@ -250,16 +257,12 @@ void VirtualNearMissCheck::check(const MatchFinder::MatchResult &Result) {
             auto Range = CharSourceRange::getTokenRange(
                 SourceRange(DerivedMD->getLocation()));
 
-            bool ApplyFix = !BaseMD->isTemplateInstantiation() &&
-                            !DerivedMD->isTemplateInstantiation();
-            auto Diag =
-                diag(DerivedMD->getBeginLoc(),
-                     "method '%0' has a similar name and the same signature as "
-                     "virtual method '%1'; did you mean to override it?")
+            diag(DerivedMD->getBeginLoc(),
+                 "method '%0' has a similar name and the same signature as "
+                 "virtual method '%1'; did you mean to override it?")
                 << DerivedMD->getQualifiedNameAsString()
-                << BaseMD->getQualifiedNameAsString();
-            if (ApplyFix)
-              Diag << FixItHint::CreateReplacement(Range, BaseMD->getName());
+                << BaseMD->getQualifiedNameAsString()
+                << FixItHint::CreateReplacement(Range, BaseMD->getName());
           }
         }
       }
diff --git a/clang-tools-extra/clang-tidy/bugprone/VirtualNearMissCheck.h b/clang-tools-extra/clang-tidy/bugprone/VirtualNearMissCheck.h
index 69ae278..ec90251 100644
--- a/clang-tools-extra/clang-tidy/bugprone/VirtualNearMissCheck.h
+++ b/clang-tools-extra/clang-tidy/bugprone/VirtualNearMissCheck.h
@@ -32,6 +32,9 @@ public:
   }
   void registerMatchers(ast_matchers::MatchFinder *Finder) override;
   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  llvm::Optional<TraversalKind> getCheckTraversalKind() const override {
+    return TK_IgnoreUnlessSpelledInSource;
+  }
 
 private:
   /// Check if the given method is possible to be overridden by some other
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone-virtual-near-miss.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone-virtual-near-miss.cpp
index 553d2f4..f3f8d32 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone-virtual-near-miss.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone-virtual-near-miss.cpp
@@ -44,9 +44,8 @@ template <typename T>
 struct TDerived : TBase<T> {
   virtual void tfunk(T t);
   // Should not apply fix for template.
-  // CHECK-MESSAGES: :[[@LINE-2]]:3: warning: method 'TDerived<double>::tfunk' has {{.*}} 'TBase<double>::tfunc'
-  // CHECK-MESSAGES: :[[@LINE-3]]:3: warning: method 'TDerived<int>::tfunk' has {{.*}} 'TBase<int>::tfunc'
-  // CHECK-FIXES: virtual void tfunk(T t);
+  // CHECK-MESSAGES: :[[@LINE-2]]:3: warning: method 'TDerived::tfunk' has {{.*}} 'TBase::tfunc'
+  // CHECK-FIXES: virtual void tfunc(T t);
 };
 
 TDerived<int> T1;
-- 
2.7.4