Fix #12138 FP passedByValue with anonymous union (#5611)

Author: chrchr-github

lib/checkother.cpp

@@ -1200,16 +1200,22 @@ static int estimateSize(const Type* type, const Settings* settings, const Symbol
         else
             cumulatedSize += size;
     };
-    for (const Variable&var : type->classScope->varlist) {
+    std::set<const Scope*> anonScopes;
+    for (const Variable& var : type->classScope->varlist) {
         int size = 0;
         if (var.isStatic())
             continue;
         if (var.isPointer() || var.isReference())
             size = settings->platform.sizeof_pointer;
         else if (var.type() && var.type()->classScope)
-            size = estimateSize(var.type(), settings, symbolDatabase, recursionDepth+1);
+            size = estimateSize(var.type(), settings, symbolDatabase, recursionDepth + 1);
         else if (var.valueType() && var.valueType()->type == ValueType::Type::CONTAINER)
             size = 3 * settings->platform.sizeof_pointer; // Just guess
+        else if (var.nameToken()->scope() != type->classScope && var.nameToken()->scope()->definedType) { // anonymous union
+            const auto ret = anonScopes.insert(var.nameToken()->scope());
+            if (ret.second)
+                size = estimateSize(var.nameToken()->scope()->definedType, settings, symbolDatabase, recursionDepth + 1);
+        }
         else
             size = symbolDatabase->sizeOfType(var.typeStartToken());
 

test/testother.cpp

@@ -2172,6 +2172,25 @@ class TestOther : public TestFixture {
               "}\n");
         ASSERT_EQUALS("[test.cpp:1]: (performance) Function parameter 't' should be passed by const reference.\n", errout.str());
 
+        check("struct S {\n" // #12138
+              "    union {\n"
+              "        int a = 0;\n"
+              "        int x;\n"
+              "    };\n"
+              "    union {\n"
+              "        int b = 0;\n"
+              "        int y;\n"
+              "    };\n"
+              "    union {\n"
+              "        int c = 0;\n"
+              "        int z;\n"
+              "    };\n"
+              "};\n"
+              "void f(S s) {\n"
+              "    if (s.x > s.y) {}\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+
         Settings settings1 = settingsBuilder().platform(Platform::Type::Win64).build();
         check("using ui64 = unsigned __int64;\n"
               "ui64 Test(ui64 one, ui64 two) { return one + two; }\n",