Fix #13685 FP uinitvar with nested compound statement scopes

PR #6714 introduced a regression in which variables initialized in nested
compound statements are incorrectly flagged as uninitialized by uninitvar.
Such scopes could be present due to usage of GNU compound statements.

Author: mptre

lib/symboldatabase.cpp

@@ -160,6 +160,7 @@ void SymbolDatabase::createSymbolDatabaseFindAllScopes()
     };
 
     std::stack<const Token*> inIfCondition;
+    std::stack<Scope*> pendingIfScopes;
 
     auto addLambda = [this, &scope](const Token* tok, const Token* lambdaEndToken) -> const Token* {
         const Token* lambdaStartToken = lambdaEndToken->link();
@@ -766,13 +767,14 @@ void SymbolDatabase::createSymbolDatabaseFindAllScopes()
                     scopeList.emplace_back(*this, tok, scope, ScopeType::eSwitch, scopeStartTok);
 
                 scope->nestedList.push_back(&scopeList.back());
-                scope = &scopeList.back();
-                if (scope->type == ScopeType::eFor)
-                    scope->checkVariable(tok->tokAt(2), AccessControl::Local); // check for variable declaration and add it to new scope if found
-                else if (scope->type == ScopeType::eCatch)
-                    scope->checkVariable(tok->tokAt(2), AccessControl::Throw); // check for variable declaration and add it to new scope if found
+                Scope* newScope = &scopeList.back();
+                if (newScope->type == ScopeType::eFor)
+                    newScope->checkVariable(tok->tokAt(2), AccessControl::Local); // check for variable declaration and add it to new scope if found
+                else if (newScope->type == ScopeType::eCatch)
+                    newScope->checkVariable(tok->tokAt(2), AccessControl::Throw); // check for variable declaration and add it to new scope if found
                 tok = tok->next();
                 inIfCondition.push(scopeStartTok);
+                pendingIfScopes.push(newScope);
             } else if (Token::Match(tok, "%var% {")) {
                 endInitList.emplace(tok->linkAt(1), scope);
                 tok = tok->next();
@@ -783,6 +785,8 @@ void SymbolDatabase::createSymbolDatabaseFindAllScopes()
                     endInitList.emplace(tok->link(), scope);
                 } else if (!inIfCondition.empty() && tok == inIfCondition.top()) {
                     inIfCondition.pop();
+                    scope = pendingIfScopes.top();
+                    pendingIfScopes.pop();
                 } else if (isExecutableScope(tok)) {
                     scopeList.emplace_back(*this, tok, scope, ScopeType::eUnconditional, tok);
                     scope->nestedList.push_back(&scopeList.back());

test/testuninitvar.cpp

@@ -76,6 +76,7 @@ class TestUninitVar : public TestFixture {
         TEST_CASE(uninitvar12); // #10218 - stream read
         TEST_CASE(uninitvar13); // #9772
         TEST_CASE(uninitvar14);
+        TEST_CASE(uninitvar15); // #13685
         TEST_CASE(uninitvar_unconditionalTry);
         TEST_CASE(uninitvar_funcptr); // #6404
         TEST_CASE(uninitvar_operator); // #6680
@@ -3647,6 +3648,17 @@ class TestUninitVar : public TestFixture {
         (checkuninitvar.valueFlowUninit)();
     }
 
+    void uninitvar15() { // #13685
+        const char code[] = "int f() {\n"
+                            "    int x;\n"
+                            "    if (!({ int *p = &x; *p = 1; 1; }))\n"
+                            "        return 0;\n"
+                            "    return x;\n"
+                            "}";
+        valueFlowUninit(code, false);
+        ASSERT_EQUALS("", errout_str());
+    }
+
     void valueFlowUninit2_value()
     {
         valueFlowUninit("void f() {\n"