Fix 10582: ValueFlow; wrong known value (#3550)

Author: pfultz2

lib/astutils.cpp

@@ -1748,7 +1748,7 @@ bool isReturnScope(const Token* const endToken, const Library* library, const To
         if (!functionScope && Token::simpleMatch(prev->link()->previous(), ") {") &&
             Token::simpleMatch(prev->link()->linkAt(-1)->previous(), "switch (") &&
             !Token::findsimplematch(prev->link(), "break", prev)) {
-            return true;
+            return isReturnScope(prev, library, unknownFunc, functionScope);
         }
         if (isEscaped(prev->link()->astTop(), functionScope, library))
             return true;

test/testcondition.cpp

@@ -3800,6 +3800,15 @@ class TestCondition : public TestFixture {
               "    do {} while (i++ == 0);\n"
               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        // #10582
+        check("static void fun(message_t *message) {\n"
+              "    if (message->length >= 1) {\n"
+              "        switch (data[0]) {}\n"
+              "    }\n"
+              "    uint8_t d0 = message->length > 0 ? data[0] : 0xff;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void alwaysTrueSymbolic()