From 67b61a0ab7447cfb6b52cf80b37f2ef95767eb27 Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Tue, 31 Oct 2023 19:08:08 +0100
Subject: [PATCH] Fix #12134 false negative: passedByValue (#5607)

---
 cfg/std.cfg        | 3 +++
 lib/checkother.cpp | 2 +-
 lib/checkother.h   | 2 +-
 test/cfg/std.cpp   | 7 +++++++
 4 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/cfg/std.cfg b/cfg/std.cfg
index cc9785244..490480a56 100644
--- a/cfg/std.cfg
+++ b/cfg/std.cfg
@@ -6977,6 +6977,7 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
   </function>
   <function name="std::string::substr">
     <use-retval/>
+    <const/>
     <returnValue type="std::string"/>
     <noreturn>false</noreturn>
     <arg nr="1" default="0" direction="in">
@@ -6990,6 +6991,7 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
   </function>
   <function name="std::wstring::substr">
     <use-retval/>
+    <const/>
     <returnValue type="std::wstring"/>
     <noreturn>false</noreturn>
     <arg nr="1" default="0" direction="in">
@@ -7003,6 +7005,7 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
   </function>
   <function name="std::basic_string::substr">
     <use-retval/>
+    <const/>
     <returnValue type="std::basic_string"/>
     <noreturn>false</noreturn>
     <arg nr="1" default="0" direction="in">
diff --git a/lib/checkother.cpp b/lib/checkother.cpp
index 8324fb130..3cd33d2e5 100644
--- a/lib/checkother.cpp
+++ b/lib/checkother.cpp
@@ -3596,7 +3596,7 @@ void CheckOther::checkShadowVariables()
     }
 }
 
-void CheckOther::shadowError(const Token *var, const Token *shadowed, std::string type)
+void CheckOther::shadowError(const Token *var, const Token *shadowed, const std::string& type)
 {
     ErrorPath errorPath;
     errorPath.emplace_back(shadowed, "Shadowed declaration");
diff --git a/lib/checkother.h b/lib/checkother.h
index 420c208b5..2499ef1b5 100644
--- a/lib/checkother.h
+++ b/lib/checkother.h
@@ -284,7 +284,7 @@ private:
     void accessMovedError(const Token *tok, const std::string &varname, const ValueFlow::Value *value, bool inconclusive);
     void funcArgNamesDifferent(const std::string & functionName, nonneg int index, const Token* declaration, const Token* definition);
     void funcArgOrderDifferent(const std::string & functionName, const Token * declaration, const Token * definition, const std::vector<const Token*> & declarations, const std::vector<const Token*> & definitions);
-    void shadowError(const Token *var, const Token *shadowed, std::string type);
+    void shadowError(const Token *var, const Token *shadowed, const std::string& type);
     void knownArgumentError(const Token *tok, const Token *ftok, const ValueFlow::Value *value, const std::string &varexpr, bool isVariableExpressionHidden);
     void knownPointerToBoolError(const Token* tok, const ValueFlow::Value* value);
     void comparePointersError(const Token *tok, const ValueFlow::Value *v1, const ValueFlow::Value *v2);
diff --git a/test/cfg/std.cpp b/test/cfg/std.cpp
index a281552c8..ecabb2f95 100644
--- a/test/cfg/std.cpp
+++ b/test/cfg/std.cpp
@@ -4638,6 +4638,13 @@ void string_view_unused(std::string_view v)
     v.substr(1, 3);
 }
 
+// cppcheck-suppress passedByValue
+void string_substr(std::string s)
+{
+    // cppcheck-suppress ignoredReturnValue
+    s.substr(1, 3);
+}
+
 void stdspan()
 {
 #ifndef __cpp_lib_span