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

[Felix Berger via cfe-commits]

================
@@ -290,69 +296,72 @@ void UnnecessaryCopyInitialization::check(
   // instantiations where the types differ and rely on implicit conversion would
   // no longer compile if we switched to a reference.
   if (differentReplacedTemplateParams(
-          NewVar->getType(), constructorArgumentType(OldVar, Result.Nodes),
+          Context.Var.getType(), constructorArgumentType(OldVar, Result.Nodes),
           *Result.Context))
     return;
 
   if (OldVar == nullptr) {
-    handleCopyFromMethodReturn(*NewVar, *BlockStmt, *Stmt, IssueFix, ObjectArg,
-                               *Result.Context);
+    // `auto NewVar = functionCall();`
+    handleCopyFromMethodReturn(Context, ObjectArg);
   } else {
-    handleCopyFromLocalVar(*NewVar, *OldVar, *BlockStmt, *Stmt, IssueFix,
-                           *Result.Context);
+    // `auto NewVar = OldVar;`
+    handleCopyFromLocalVar(Context, *OldVar);
   }
 }
 
-void UnnecessaryCopyInitialization::makeDiagnostic(
-    DiagnosticBuilder Diagnostic, const VarDecl &Var, const Stmt &BlockStmt,
-    const DeclStmt &Stmt, ASTContext &Context, bool IssueFix) {
-  const bool IsVarUnused = isVariableUnused(Var, BlockStmt, Context);
-  Diagnostic << &Var << IsVarUnused;
-  if (!IssueFix)
-    return;
-  if (IsVarUnused)
-    recordRemoval(Stmt, Context, Diagnostic);
-  else
-    recordFixes(Var, Context, Diagnostic);
-}
-
 void 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))
+    const CheckContext &Ctx, const VarDecl *ObjectArg) {
+  bool IsConstQualified = Ctx.Var.getType().isConstQualified();
+  if (!IsConstQualified && !Ctx.IsVarOnlyUsedAsConst)
     return;
   if (ObjectArg != nullptr &&
-      !isInitializingVariableImmutable(*ObjectArg, BlockStmt, Context,
+      !isInitializingVariableImmutable(*ObjectArg, Ctx.BlockStmt, Ctx.ASTCtx,
                                        ExcludedContainerTypes))
     return;
-
-  auto Diagnostic =
-      diag(Var.getLocation(),
-           "the %select{|const qualified }0variable %1 is copy-constructed "
-           "from a const reference%select{"
-           "%select{ but is only used as const reference|}0"
-           "| but is never used}2; consider "
-           "%select{making it a const reference|removing the statement}2")
-      << IsConstQualified;
-  makeDiagnostic(std::move(Diagnostic), Var, BlockStmt, Stmt, Context,
-                 IssueFix);
+  diagnoseCopyFromMethodReturn(Ctx, ObjectArg);
 }
 
 void UnnecessaryCopyInitialization::handleCopyFromLocalVar(
-    const VarDecl &Var, const VarDecl &OldVar, const Stmt &BlockStmt,
-    const DeclStmt &Stmt, bool IssueFix, ASTContext &Context) {
-  if (!isOnlyUsedAsConst(Var, BlockStmt, Context) ||
-      !isInitializingVariableImmutable(OldVar, BlockStmt, Context,
+    const CheckContext &Ctx, const VarDecl &OldVar) {
+  if (!Ctx.IsVarOnlyUsedAsConst ||
+      !isInitializingVariableImmutable(OldVar, Ctx.BlockStmt, Ctx.ASTCtx,
                                        ExcludedContainerTypes))
     return;
-  auto Diagnostic = diag(Var.getLocation(),
-                         "local copy %1 of the variable %0 is never modified"
-                         "%select{| and never used}2; consider "
-                         "%select{avoiding the copy|removing the statement}2")
-                    << &OldVar;
-  makeDiagnostic(std::move(Diagnostic), Var, BlockStmt, Stmt, Context,
-                 IssueFix);
+  diagnoseCopyFromLocalVar(Ctx, OldVar);
+}
+
+void UnnecessaryCopyInitialization::diagnoseCopyFromMethodReturn(
+    const CheckContext &Ctx, const VarDecl *ObjectArg) {
----------------
fberger wrote:

It doesn't look like ObjectArg is used. Can we remove it?

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