From 74088f0ea1ed1e6a63db5581efb607d3d1f528b2 Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Thu, 11 Apr 2024 14:37:07 +0200
Subject: [PATCH 1/4] Update checkclass.cpp

---
 lib/checkclass.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/checkclass.cpp b/lib/checkclass.cpp
index 1a42f8ab820..cbf21898579 100644
--- a/lib/checkclass.cpp
+++ b/lib/checkclass.cpp
@@ -3327,6 +3327,8 @@ void CheckClass::checkReturnByReference()
         for (const Function& func : classScope->functionList) {
             if (Function::returnsPointer(&func) || Function::returnsReference(&func) || Function::returnsStandardType(&func))
                 continue;
+            if (func.isImplicitlyVirtual())
+                continue;
             if (const Variable* var = getSingleReturnVar(func.functionScope)) {
                 if (!var->valueType())
                     continue;

From 754b0070c03ae91554ef2610ee65310fdeecdbb5 Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Thu, 11 Apr 2024 14:38:23 +0200
Subject: [PATCH 2/4] Update testclass.cpp

---
 test/testclass.cpp | 34 +++++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/test/testclass.cpp b/test/testclass.cpp
index 4d62db1eadb..a0e52a94bcf 100644
--- a/test/testclass.cpp
+++ b/test/testclass.cpp
@@ -8960,21 +8960,29 @@ class TestClass : public TestFixture {
     }
 
     void returnByReference() {
-        checkReturnByReference("struct T { int a[10]; };" // #12546
-                               "struct S {"
-                               "    T t;"
-                               "    int i;"
-                               "    std::string s;"
-                               "    T getT() const { return t; }"
-                               "    int getI() const { return i; }"
-                               "    std::string getS() const { return s; }"
-                               "    unknown_t f() { return; }"
-                               "};");
-        ASSERT_EQUALS("[test.cpp:1]: (performance) Function 'getT()' should return member 't' by const reference.\n"
-                      "[test.cpp:1]: (performance) Function 'getS()' should return member 's' by const reference.\n",
+        checkReturnByReference("struct T { int a[10]; };\n" // #12546
+                               "struct S {\n"
+                               "    T t;\n"
+                               "    int i;\n"
+                               "    std::string s;\n"
+                               "    T getT() const { return t; }\n"
+                               "    int getI() const { return i; }\n"
+                               "    std::string getS() const { return s; }\n"
+                               "    unknown_t f() { return; }\n"
+                               "};\n");
+        ASSERT_EQUALS("[test.cpp:6]: (performance) Function 'getT()' should return member 't' by const reference.\n"
+                      "[test.cpp:8]: (performance) Function 'getS()' should return member 's' by const reference.\n",
                       errout_str());
-    }
 
+        checkReturnByReference("struct B {\n" // #12608
+                               "    virtual std::string f() { return \"abc\"; }\n"
+                               "};\n"
+                               "struct D : B {\n"
+                               "    std::string f() override { return s; }\n"
+                               "    std::string s;\n"
+                               "}");
+        ASSERT_EQUALS("", errout_str());
+    }
 };
 
 REGISTER_TEST(TestClass)

From 7adfb08f31ee3b4487850b2182263762166414b7 Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Thu, 11 Apr 2024 15:13:07 +0200
Subject: [PATCH 3/4] Update checkclass.cpp

---
 lib/checkclass.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/checkclass.cpp b/lib/checkclass.cpp
index cbf21898579..2961873de26 100644
--- a/lib/checkclass.cpp
+++ b/lib/checkclass.cpp
@@ -3332,6 +3332,8 @@ void CheckClass::checkReturnByReference()
             if (const Variable* var = getSingleReturnVar(func.functionScope)) {
                 if (!var->valueType())
                     continue;
+                if (var->isArgument())
+                    continue;
                 const bool isContainer = var->valueType()->type == ValueType::Type::CONTAINER && var->valueType()->container;
                 const bool isView = isContainer && var->valueType()->container->view;
                 bool warn = isContainer && !isView;

From 7bfb95cc1079b14e5b8fb41bf83f8ccacab98411 Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Thu, 11 Apr 2024 15:15:20 +0200
Subject: [PATCH 4/4] Update testclass.cpp

---
 test/testclass.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/test/testclass.cpp b/test/testclass.cpp
index a0e52a94bcf..b0ffbb6b550 100644
--- a/test/testclass.cpp
+++ b/test/testclass.cpp
@@ -8980,7 +8980,12 @@ class TestClass : public TestFixture {
                                "struct D : B {\n"
                                "    std::string f() override { return s; }\n"
                                "    std::string s;\n"
-                               "}");
+                               "};\n");
+        ASSERT_EQUALS("", errout_str());
+
+        checkReturnByReference("struct S {\n"
+                               "    std::string f(std::string s) { return s; }\n"
+                               "};\n");
         ASSERT_EQUALS("", errout_str());
     }
 };