[clang-tools-extra] [clang-tidy] performance-unnecessary-copy-init: Add a hook... (PR #73921)

[Clement Courbet via cfe-commits]

https://github.com/legrosbuffle created https://github.com/llvm/llvm-project/pull/73921

... so that derived checks can implement custom behaviour. Does nothing by default, which makes this  an NFC.

>From e251c440b42fe67dee4022d08d05e96d30d6aa02 Mon Sep 17 00:00:00 2001
From: Clement Courbet <courbet at google.com>
Date: Thu, 30 Nov 2023 11:08:51 +0100
Subject: [PATCH] [clang-tidy] performance-unnecessary-copy-init: Add a hook...

... so that derived checks can implement custom behaviour.
---
 .../UnnecessaryCopyInitialization.cpp         | 24 ++++++++++++-------
 .../UnnecessaryCopyInitialization.h           |  9 +++++--
 2 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp b/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
index 990e20400fbfcd2..966071e92833b87 100644
--- a/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
+++ b/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
@@ -294,24 +294,28 @@ void UnnecessaryCopyInitialization::check(
     return;
 
   if (OldVar == nullptr) {
-    handleCopyFromMethodReturn(*NewVar, *BlockStmt, *Stmt, IssueFix, ObjectArg,
-                               *Result.Context);
+    if (handleCopyFromMethodReturn(*NewVar, *BlockStmt, *Stmt, IssueFix,
+                                   ObjectArg, *Result.Context)) {
+      onWarningEmitted(*NewVar, *BlockStmt, *Result.Context);
+    }
   } else {
-    handleCopyFromLocalVar(*NewVar, *OldVar, *BlockStmt, *Stmt, IssueFix,
-                           *Result.Context);
+    if (handleCopyFromLocalVar(*NewVar, *OldVar, *BlockStmt, *Stmt, IssueFix,
+                               *Result.Context)) {
+      onWarningEmitted(*NewVar, *BlockStmt, *Result.Context);
+    }  
   }
 }
 
-void UnnecessaryCopyInitialization::handleCopyFromMethodReturn(
+bool UnnecessaryCopyInitialization::handleCopyFromMethodReturn(
     const VarDecl &Var, const Stmt &BlockStmt, const DeclStmt &Stmt,
     bool IssueFix, const VarDecl *ObjectArg, ASTContext &Context) {
   bool IsConstQualified = Var.getType().isConstQualified();
   if (!IsConstQualified && !isOnlyUsedAsConst(Var, BlockStmt, Context))
-    return;
+    return false;
   if (ObjectArg != nullptr &&
       !isInitializingVariableImmutable(*ObjectArg, BlockStmt, Context,
                                        ExcludedContainerTypes))
-    return;
+    return false;
   if (isVariableUnused(Var, BlockStmt, Context)) {
     auto Diagnostic =
         diag(Var.getLocation(),
@@ -331,15 +335,16 @@ void UnnecessaryCopyInitialization::handleCopyFromMethodReturn(
     if (IssueFix)
       recordFixes(Var, Context, Diagnostic);
   }
+  return true;
 }
 
-void UnnecessaryCopyInitialization::handleCopyFromLocalVar(
+bool UnnecessaryCopyInitialization::handleCopyFromLocalVar(
     const VarDecl &NewVar, const VarDecl &OldVar, const Stmt &BlockStmt,
     const DeclStmt &Stmt, bool IssueFix, ASTContext &Context) {
   if (!isOnlyUsedAsConst(NewVar, BlockStmt, Context) ||
       !isInitializingVariableImmutable(OldVar, BlockStmt, Context,
                                        ExcludedContainerTypes))
-    return;
+    return false;
 
   if (isVariableUnused(NewVar, BlockStmt, Context)) {
     auto Diagnostic = diag(NewVar.getLocation(),
@@ -358,6 +363,7 @@ void UnnecessaryCopyInitialization::handleCopyFromLocalVar(
     if (IssueFix)
       recordFixes(NewVar, Context, Diagnostic);
   }
+  return true;
 }
 
 void UnnecessaryCopyInitialization::storeOptions(
diff --git a/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.h b/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.h
index ea009ba9979de97..7d76c9e7cab940c 100644
--- a/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.h
+++ b/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.h
@@ -33,13 +33,18 @@ class UnnecessaryCopyInitialization : public ClangTidyCheck {
   void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
 
 private:
-  void handleCopyFromMethodReturn(const VarDecl &Var, const Stmt &BlockStmt,
+  bool handleCopyFromMethodReturn(const VarDecl &Var, const Stmt &BlockStmt,
                                   const DeclStmt &Stmt, bool IssueFix,
                                   const VarDecl *ObjectArg,
                                   ASTContext &Context);
-  void handleCopyFromLocalVar(const VarDecl &NewVar, const VarDecl &OldVar,
+  bool handleCopyFromLocalVar(const VarDecl &NewVar, const VarDecl &OldVar,
                               const Stmt &BlockStmt, const DeclStmt &Stmt,
                               bool IssueFix, ASTContext &Context);
+
+  // A hook called for each emitted warning.
+  virtual void onWarningEmitted(const VarDecl &Var, const Stmt &BlockStmt,
+                                ASTContext &context) {}
+
   const std::vector<StringRef> AllowedTypes;
   const std::vector<StringRef> ExcludedContainerTypes;
 };