From 79f091c59a3664af6b22563d4b692ef93a82931a Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Thu, 21 Jul 2022 22:15:16 +0200
Subject: [PATCH] Fix uselessCallsConstructor TODOs (#4299)

* Fix uselessCallsConstructor TODOs

* Format
---
 lib/checkstl.cpp | 16 +++++++++++++---
 test/teststl.cpp | 17 +++++++++++------
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/lib/checkstl.cpp b/lib/checkstl.cpp
index 793523c24..fbdbc8661 100644
--- a/lib/checkstl.cpp
+++ b/lib/checkstl.cpp
@@ -2175,9 +2175,19 @@ void CheckStl::uselessCalls()
                 uselessCallsEmptyError(tok->next());
             else if (Token::Match(tok, "[{};] std :: remove|remove_if|unique (") && tok->tokAt(5)->nextArgument())
                 uselessCallsRemoveError(tok->next(), tok->strAt(3));
-            else if (printPerformance && Token::Match(tok, "%var% = { %var% . begin ( ) ,") &&
-                     tok->valueType() && tok->valueType()->type == ValueType::CONTAINER && tok->varId() == tok->tokAt(3)->varId()) {
-                uselessCallsConstructorError(tok);
+            else if (printPerformance && tok->valueType() && tok->valueType()->type == ValueType::CONTAINER) {
+                if (Token::Match(tok, "%var% = { %var% . begin ( ) ,") && tok->varId() == tok->tokAt(3)->varId())
+                    uselessCallsConstructorError(tok);
+                else if (const Variable* var = tok->variable()) {
+                    std::string pattern = "%var% = ";
+                    for (const Token* t = var->typeStartToken(); t != var->typeEndToken()->next(); t = t->next()) {
+                        pattern += t->str();
+                        pattern += ' ';
+                    }
+                    pattern += "{|( %varid% . begin ( ) ,";
+                    if (Token::Match(tok, pattern.c_str(), tok->varId()))
+                        uselessCallsConstructorError(tok);
+                }
             }
         }
     }
diff --git a/test/teststl.cpp b/test/teststl.cpp
index 2ac0aa57e..12b91143f 100644
--- a/test/teststl.cpp
+++ b/test/teststl.cpp
@@ -4202,17 +4202,22 @@ private:
               "    s = std::string{ s.begin(), s.begin() + end };\n"
               "    return s;\n"
               "}\n");
-        TODO_ASSERT_EQUALS("[test.cpp:2]: (performance) Inefficient constructor call: container 's' is assigned a partial copy of itself. Use erase() or resize() instead.\n",
-                           "",
-                           errout.str());
+        ASSERT_EQUALS("[test.cpp:2]: (performance) Inefficient constructor call: container 's' is assigned a partial copy of itself. Use erase() or resize() instead.\n",
+                      errout.str());
 
         check("std::string f(std::string s, std::size_t end) {\n"
               "    s = std::string(s.begin(), s.begin() + end);\n"
               "    return s;\n"
               "}\n");
-        TODO_ASSERT_EQUALS("[test.cpp:2]: (performance) Inefficient constructor call: container 's' is assigned a partial copy of itself. Use erase() or resize() instead.\n",
-                           "",
-                           errout.str());
+        ASSERT_EQUALS("[test.cpp:2]: (performance) Inefficient constructor call: container 's' is assigned a partial copy of itself. Use erase() or resize() instead.\n",
+                      errout.str());
+
+        check("std::vector<int> f(std::vector<int> v, std::size_t end) {\n"
+              "    v = std::vector<int>(v.begin(), v.begin() + end);\n"
+              "    return v;\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:2]: (performance) Inefficient constructor call: container 'v' is assigned a partial copy of itself. Use erase() or resize() instead.\n",
+                      errout.str());
     }
 
     void stabilityOfChecks() {