Fixed #8941 (False Positive: Variable 'f' is assigned a value that is never used.)

lib/token.cpp

@@ -18,6 +18,7 @@
 
 #include "token.h"
 
+#include "astutils.h"
 #include "errorlogger.h"
 #include "library.h"
 #include "settings.h"
@@ -1173,13 +1174,24 @@ static const Token* goToRightParenthesis(const Token* start, const Token* end)
 std::pair<const Token *, const Token *> Token::findExpressionStartEndTokens() const
 {
     const Token * const top = this;
+
+    // find start node in AST tree
     const Token *start = top;
     while (start->astOperand1() &&
            (start->astOperand2() || !start->isUnaryPreOp() || Token::simpleMatch(start, "( )") || start->str() == "{"))
         start = start->astOperand1();
+
+    // find end node in AST tree
     const Token *end = top;
     while (end->astOperand1() && (end->astOperand2() || end->isUnaryPreOp())) {
-        if (Token::Match(end,"(|[") &&
+        // lambda..
+        if (end->str() == "[") {
+            const Token *lambdaEnd = findLambdaEndToken(end);
+            if (lambdaEnd) {
+                end = lambdaEnd;
+                break;
+            }
+        } else if (Token::Match(end,"(|[") &&
                    !(Token::Match(end, "( %type%") && !end->astOperand2())) {
             end = end->link();
             break;
@@ -1187,6 +1199,7 @@ std::pair<const Token *, const Token *> Token::findExpressionStartEndTokens() co
         end = end->astOperand2() ? end->astOperand2() : end->astOperand1();
     }
 
+    // skip parentheses
     start = goToLeftParenthesis(start, end);
     end = goToRightParenthesis(start, end);
     if (Token::simpleMatch(end, "{"))

test/testunusedvar.cpp

@@ -181,6 +181,7 @@ private:
         TEST_CASE(localvarFuncPtr); // #7194
         TEST_CASE(localvarAddr); // #7477
         TEST_CASE(localvarDelete);
+        TEST_CASE(localvarReturnCallLambda); // #8941
 
         TEST_CASE(localvarCppInitialization);
         TEST_CASE(localvarCpp11Initialization);
@@ -4232,6 +4233,14 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void localvarReturnCallLambda() {
+        functionVariableUsage("int foo() {\n"
+                              "    auto f = []{return 1};\n"
+                              "    return f();\n"
+                              "}");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void localvarCppInitialization() {
         functionVariableUsage("void foo() {\n"
                               "    int buf[6];\n"