tweak; we can warn about unused union members

Author: danmar

lib/checkunusedvar.cpp

@@ -1615,41 +1615,6 @@ void CheckUnusedVar::checkStructMemberUsage()
             }
         }
 
-        // #7458 - if this is a union and any member is used, don't warn about other members
-        bool unionWithUsedMember = false;
-        if (scope.type == ScopeType::eUnion) {
-            // Check if any direct member of the union is used
-            for (const Variable &unionVar : scope.varlist) {
-                for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) {
-                    if (tok->variable() == &unionVar && tok != unionVar.nameToken()) {
-                        unionWithUsedMember = true;
-                        break;
-                    }
-                }
-                if (unionWithUsedMember)
-                    break;
-            }
-            // Also check if any member of nested structs in this union is used
-            if (!unionWithUsedMember) {
-                for (const Scope *nestedScope : scope.nestedList) {
-                    if (nestedScope->type == ScopeType::eStruct) {
-                        for (const Variable &structVar : nestedScope->varlist) {
-                            for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) {
-                                if (tok->variable() == &structVar && tok != structVar.nameToken()) {
-                                    unionWithUsedMember = true;
-                                    break;
-                                }
-                            }
-                            if (unionWithUsedMember)
-                                break;
-                        }
-                        if (unionWithUsedMember)
-                            break;
-                    }
-                }
-            }
-        }
-
         for (const Variable &var : scope.varlist) {
             // only warn for variables without side effects
             if (!var.typeStartToken()->isStandardType() && !var.isPointer() && !astIsContainer(var.nameToken()) && !isRecordTypeWithoutSideEffects(var.type()))
@@ -1667,9 +1632,6 @@ void CheckUnusedVar::checkStructMemberUsage()
             if (structInUnionWithUsedMember)
                 continue;
 
-            // Skip reporting unused members if this is a union and any member is used
-            if (unionWithUsedMember)
-                continue;
 
             // Check if the struct member variable is used anywhere in the file
             bool use = false;

test/testunusedvar.cpp

@@ -1411,14 +1411,16 @@ class TestUnusedVar : public TestFixture {
                                "    double asDouble;\n"
                                "    uint64_t asInt;\n"
                                "    struct {\n"
-                               "        uint32_t lo, hi;\n"
+                               "        uint32_t lo, hi;\n" // <- no FP about lo because hi is used
                                "    } asIntel;\n"
                                "};\n"
                                "void f() {\n"
                                "    union DoubleInt di;\n"
                                "    di.asIntel.hi = 3;\n"
                                "}");
-        ASSERT_EQUALS("", errout_str());
+        ASSERT_EQUALS("[test.cpp:2:12]: (style) union member 'DoubleInt::asDouble' is never used. [unusedStructMember]\n"
+                      "[test.cpp:3:14]: (style) union member 'DoubleInt::asInt' is never used. [unusedStructMember]\n",
+		      errout_str());
     }
 
     void structmember2() {