From cf475fab515bc27fd21326d4b93d5961bc12cc77 Mon Sep 17 00:00:00 2001
From: Paul <pfultz2@yahoo.com>
Date: Fri, 26 Jun 2020 15:47:59 -0500
Subject: [PATCH] Fix issue 9778: False positive: constParameter when returning
 non-const reference cast

---
 lib/checkother.cpp | 4 +++-
 test/testother.cpp | 8 ++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/lib/checkother.cpp b/lib/checkother.cpp
index c68c80dfa..b2b912a38 100644
--- a/lib/checkother.cpp
+++ b/lib/checkother.cpp
@@ -1368,8 +1368,10 @@ void CheckOther::checkConstVariable()
         if (Function::returnsReference(function)) {
             std::vector<const Token*> returns = Function::findReturns(function);
             if (std::any_of(returns.begin(), returns.end(), [&](const Token* retTok) {
-            if (retTok->varId() == var->declarationId())
+                if (retTok->varId() == var->declarationId())
                     return true;
+                while (retTok && retTok->isCast())
+                    retTok = retTok->astOperand2();
                 while (Token::simpleMatch(retTok, "."))
                     retTok = retTok->astOperand2();
                 const Variable* retVar = getLifetimeVariable(getParentLifetime(retTok));
diff --git a/test/testother.cpp b/test/testother.cpp
index 58be8aa99..3b80943d1 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -2040,6 +2040,14 @@ private:
               "}\n");
         ASSERT_EQUALS("", errout.str());
 
+        // #9778
+        check("struct A {};\n"
+              "struct B : A {};\n"
+              "B& f(A& x) {\n"
+              "    return static_cast<B&>(x);\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+
         check("void e();\n"
               "void g(void);\n"
               "void h(void);\n"