[clang-tidy][modernize-return-braced-init-list]fix false-positives

clang-tools-extra/clang-tidy/modernize/ReturnBracedInitListCheck.cpp

@@ -9,6 +9,7 @@
 #include "ReturnBracedInitListCheck.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Lex/Lexer.h"
 #include "clang/Tooling/FixIt.h"
 
@@ -17,11 +18,27 @@ 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(
+      hasDeclaration(
+          // Container(size_type count, const T &value,
+          //           const Allocator &alloc = Allocator());
+          cxxConstructorDecl(parameterCountIs(3),
+                             hasParameter(0, hasType(qualType(hasCanonicalType(
+                                                 isInteger())))))),
+      hasType(cxxRecordDecl(hasAnyName("::std::basic_string", "::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(

clang-tools-extra/docs/ReleaseNotes.rst

@@ -269,6 +269,11 @@ 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``.
+
 - 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.

clang-tools-extra/test/clang-tidy/checkers/modernize/return-braced-init-list.cpp

@@ -30,12 +30,16 @@ class initializer_list {
 };
 
 template <typename T>
+struct allocator {};
+
+template <typename T, typename Allocator = ::std::allocator<T>>
 class vector {
 public:
-  vector(T) {}
-  vector(std::initializer_list<T>) {}
+  vector(T);
+  vector(size_t, T, const Allocator &alloc = Allocator());
+  vector(std::initializer_list<T>);
 };
-}
+} // namespace std
 
 class Bar {};
 
@@ -98,12 +102,26 @@ 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 {};
 }