[clang-tools-extra] [clang-tidy][modernize-return-braced-init-list]fix false-positives (PR #68491)

[Congcong Cai via cfe-commits]

https://github.com/HerrCai0907 created https://github.com/llvm/llvm-project/pull/68491

fix false-positives when constructing the container with ``count`` copies of elements with value ``value``
(e.g., ``vector(size_type count, const T& value);``). Fixes: #68159

>From d1b76f7649e1b1239ad328c7da9b1f9d8fb2c5f3 Mon Sep 17 00:00:00 2001
From: Congcong Cai <congcongcai0907 at 163.com>
Date: Sun, 8 Oct 2023 01:00:15 +0800
Subject: [PATCH] [clang-tidy][modernize-return-braced-init-list]fix
 false-positives

when constructing the container with ``count`` copies of
elements with value ``value``
(e.g., ``vector(size_type count, const T& value);``).
Fixes: #68159
---
 .../modernize/ReturnBracedInitListCheck.cpp   | 16 +++++++++++---
 clang-tools-extra/docs/ReleaseNotes.rst       |  6 ++++++
 .../modernize/return-braced-init-list.cpp     | 21 ++++++++++++++++---
 3 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/modernize/ReturnBracedInitListCheck.cpp b/clang-tools-extra/clang-tidy/modernize/ReturnBracedInitListCheck.cpp
index 407de610d13a79f..edb0468d2914600 100644
--- a/clang-tools-extra/clang-tidy/modernize/ReturnBracedInitListCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/ReturnBracedInitListCheck.cpp
@@ -17,11 +17,21 @@ using namespace clang::ast_matchers;
 namespace clang::tidy::modernize {
 
 void ReturnBracedInitListCheck::registerMatchers(MatchFinder *Finder) {
-  // Skip list initialization and constructors with an initializer list.
+  auto SemanticallyDifferentContainer = allOf(
+      argumentCountIs(2), hasArgument(0, hasType(isInteger())),
+      hasType(cxxRecordDecl(hasAnyName("::std::vector", "::std::deque",
+                                       "::std::forward_list", "::std::list"))));
+
   auto ConstructExpr =
       cxxConstructExpr(
-          unless(anyOf(hasDeclaration(cxxConstructorDecl(isExplicit())),
-                       isListInitialization(), hasDescendant(initListExpr()))))
+          unless(anyOf(
+              // Skip explicit constructor.
+              hasDeclaration(cxxConstructorDecl(isExplicit())),
+              // Skip list initialization and constructors with an initializer
+              // list.
+              isListInitialization(), hasDescendant(initListExpr()),
+              // Skip container `vector(size_type, const T&)`.
+              SemanticallyDifferentContainer)))
           .bind("ctor");
 
   Finder->addMatcher(
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index c1b926b296b055a..053d6b20a6fe875 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -269,6 +269,12 @@ Changes in existing checks
   <clang-tidy/checks/modernize/loop-convert>` to support for-loops with
   iterators initialized by free functions like ``begin``, ``end``, or ``size``.
 
+- Improved :doc:`modernize-return-braced-init-list
+  <clang-tidy/checks/modernize/return-braced-init-list>` check to ignore
+  false-positives when constructing the container with ``count`` copies of
+  elements with value ``value``
+  (e.g., ``vector(size_type count, const T& value);``).
+
 - Improved :doc:`modernize-use-equals-delete
   <clang-tidy/checks/modernize/use-equals-delete>` check to ignore
   false-positives when special member function is actually used or implicit.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/return-braced-init-list.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/return-braced-init-list.cpp
index 4db1d49da2ea8b9..b9526ce5746dec2 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/modernize/return-braced-init-list.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/return-braced-init-list.cpp
@@ -32,8 +32,9 @@ class initializer_list {
 template <typename T>
 class vector {
 public:
-  vector(T) {}
-  vector(std::initializer_list<T>) {}
+  vector(T);
+  vector(size_t, T);
+  vector(std::initializer_list<T>);
 };
 }
 
@@ -98,12 +99,26 @@ Foo f6() {
   return Foo(b6, 1);
 }
 
-std::vector<int> f7() {
+std::vector<int> vectorWithOneParameter() {
   int i7 = 1;
   return std::vector<int>(i7);
   // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: avoid repeating the return type
 }
 
+std::vector<int> vectorIntWithTwoParameter() {
+  return std::vector<int>(1, 2);
+}
+
+std::vector<double> vectorDoubleWithTwoParameter() {
+  return std::vector<double>(1, 2.1);
+}
+struct A {};
+std::vector<A> vectorRecordWithTwoParameter() {
+  A a{};
+  return std::vector<A>(1, a);
+}
+
+
 Bar f8() {
   return {};
 }