Fix #12944 FP uninitvar reported in lambda (#8237)

Author: chrchr-github

lib/valueflow.cpp

@@ -5958,9 +5958,12 @@ static Token* findStartToken(const Variable* var, Token* start, const Library& l
     }))
         return first->previous();
     // Compute the outer scope
-    while (scope && scope->nestedIn != var->scope())
+    while (scope && scope->nestedIn != var->scope()) {
+        if (scope->type == ScopeType::eLambda && !Token::simpleMatch(scope->bodyEnd, "} ("))
+            return start;
         scope = scope->nestedIn;
-    if (!scope)
+    }
+    if (!scope || (scope->type == ScopeType::eLambda && !Token::simpleMatch(scope->bodyEnd, "} (")))
         return start;
     auto* tok = const_cast<Token*>(scope->bodyStart);
     if (!tok)

test/testuninitvar.cpp

@@ -6663,6 +6663,26 @@ class TestUninitVar : public TestFixture {
                         "    return ret;\n"
                         "}\n");
         ASSERT_EQUALS("", errout_str());
+
+        valueFlowUninit("int f() {\n" // #12944
+                        "    int i;\n"
+                        "    auto x = [&]() { return i; };\n"
+                        "    i = 5;\n"
+                        "    return x();\n"
+                        "}\n"
+                        "int g() {\n"
+                        "    int i;\n"
+                        "    {\n"
+                        "        auto x = [&]() { return i; };\n"
+                        "        i = 5;\n"
+                        "        return x();\n"
+                        "    }\n"
+                        "}\n"
+                        "int h() {\n"
+                        "    int j;\n"
+                        "    return [&]() { return j; }();\n"
+                        "}\n");
+        ASSERT_EQUALS("[test.cpp:17:27]: (error) Uninitialized variable: j [uninitvar]\n", errout_str());
     }
 
     void valueFlowUninitBreak() { // Do not show duplicate warnings about the same uninitialized value