[clang-tools-extra] [clang-tidy] fix false negatives for performance-inefficient-vector-operation (PR #95667)

[Congcong Cai via cfe-commits]

https://github.com/HerrCai0907 created https://github.com/llvm/llvm-project/pull/95667

Fixes: #95596
Check will warn if the loop var type is not same as var init expr type


>From 5a4a4aac26a2a4078f07977b5101d3a1e22a3e0c Mon Sep 17 00:00:00 2001
From: Congcong Cai <congcongcai0907 at 163.com>
Date: Sat, 15 Jun 2024 16:24:55 +0000
Subject: [PATCH] [clang-tidy] fix false negatives for
 performance-inefficient-vector-operation

Fixes: #95596
Check will warn if the loop var type is not same as var init expr type
---
 .../InefficientVectorOperationCheck.cpp       |  6 ++--
 clang-tools-extra/docs/ReleaseNotes.rst       |  5 +++
 .../inefficient-vector-operation.cpp          | 35 +++++++++++++++++++
 3 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/performance/InefficientVectorOperationCheck.cpp b/clang-tools-extra/clang-tidy/performance/InefficientVectorOperationCheck.cpp
index 20aea5a79fe9a..dc6e0cf9c7d12 100644
--- a/clang-tools-extra/clang-tidy/performance/InefficientVectorOperationCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/InefficientVectorOperationCheck.cpp
@@ -105,9 +105,9 @@ void InefficientVectorOperationCheck::addMatcher(
           onImplicitObjectArgument(declRefExpr(to(TargetVarDecl))))
           .bind(AppendCallName);
   const auto AppendCall = expr(ignoringImplicit(AppendCallExpr));
-  const auto LoopVarInit =
-      declStmt(hasSingleDecl(varDecl(hasInitializer(integerLiteral(equals(0))))
-                                 .bind(LoopInitVarName)));
+  const auto LoopVarInit = declStmt(hasSingleDecl(
+      varDecl(hasInitializer(ignoringParenImpCasts(integerLiteral(equals(0)))))
+          .bind(LoopInitVarName)));
   const auto RefersToLoopVar = ignoringParenImpCasts(
       declRefExpr(to(varDecl(equalsBoundNode(LoopInitVarName)))));
 
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 7092d0b6fdb02..3bdd735f7dcf7 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -387,6 +387,11 @@ Changes in existing checks
 - Improved :doc:`modernize-use-using <clang-tidy/checks/modernize/use-using>`
   check by adding support for detection of typedefs declared on function level.
 
+- Improved :doc:`performance-inefficient-vector-operation
+  <clang-tidy/checks/performance/inefficient-vector-operation>` fixing false
+  negatives caused by different variable definition type and variable initial
+  value type in loop initialization expression.
+
 - Improved :doc:`performance-move-const-arg
   <clang-tidy/checks/performance/move-const-arg>` check by ignoring
   ``std::move()`` calls when their target is used as an rvalue.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/performance/inefficient-vector-operation.cpp b/clang-tools-extra/test/clang-tidy/checkers/performance/inefficient-vector-operation.cpp
index c28592f4d6368..50424920d72b7 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/performance/inefficient-vector-operation.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/performance/inefficient-vector-operation.cpp
@@ -387,3 +387,38 @@ void foo(const StructWithFieldContainer &Src) {
     B.push_back(Number);
   }
 }
+
+namespace gh95596 {
+
+void f(std::vector<int>& t) {
+  {
+    std::vector<int> gh95596_0;
+    // CHECK-FIXES: gh95596_0.reserve(10);
+    for (unsigned i = 0; i < 10; ++i)
+      gh95596_0.push_back(i);
+      // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: 'push_back' is called inside a loop; consider pre-allocating the container capacity before the loop
+  }
+  {
+    std::vector<int> gh95596_1;
+    // CHECK-FIXES: gh95596_1.reserve(10);
+    for (int i = 0U; i < 10; ++i)
+      gh95596_1.push_back(i);
+      // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: 'push_back' is called inside a loop; consider pre-allocating the container capacity before the loop
+  }
+  {
+    std::vector<int> gh95596_2;
+    // CHECK-FIXES: gh95596_2.reserve(10);
+    for (unsigned i = 0U; i < 10; ++i)
+      gh95596_2.push_back(i);
+      // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: 'push_back' is called inside a loop; consider pre-allocating the container capacity before the loop
+  }
+  {
+    std::vector<int> gh95596_3;
+    // CHECK-FIXES: gh95596_3.reserve(10U);
+    for (int i = 0; i < 10U; ++i)
+      gh95596_3.push_back(i);
+      // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: 'push_back' is called inside a loop; consider pre-allocating the container capacity before the loop
+  }
+}
+
+} // namespace gh95596
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