From f7029e62acd57838493fc43bf802fb9de3c99990 Mon Sep 17 00:00:00 2001
From: Paul <pfultz2@yahoo.com>
Date: Wed, 17 Jun 2020 17:06:06 -0500
Subject: [PATCH] Check for mor FPs

---
 lib/checkstl.cpp           | 15 +++++++++++----
 lib/token.cpp              | 16 ++++++++++++++--
 test/testautovariables.cpp |  3 ++-
 test/teststl.cpp           | 38 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 65 insertions(+), 7 deletions(-)

diff --git a/lib/checkstl.cpp b/lib/checkstl.cpp
index b7df538ce..86d768953 100644
--- a/lib/checkstl.cpp
+++ b/lib/checkstl.cpp
@@ -2396,16 +2396,23 @@ void CheckStl::useStlAlgorithm()
 
 static bool isMutex(const Variable* var)
 {
-    const Token* tok = var->typeStartToken();
+    const Token* tok = Token::typeDecl(var->nameToken()).first;
     return Token::Match(tok, "std :: mutex|recursive_mutex|timed_mutex|recursive_timed_mutex|shared_mutex");
 }
 
 static bool isLockGuard(const Variable* var)
 {
-    const Token* tok = var->typeStartToken();
+    const Token* tok = Token::typeDecl(var->nameToken()).first;
     return Token::Match(tok, "std :: lock_guard|unique_lock|scoped_lock");
 }
 
+static bool isLocalMutex(const Variable* var, const Scope* scope)
+{
+    if (!var)
+        return false;
+    return !var->isReference() && !var->isRValueReference() && !var->isStatic() && var->scope() == scope;
+}
+
 void CheckStl::globalLockGuardError(const Token* tok)
 {
     reportError(tok, Severity::warning,
@@ -2430,7 +2437,7 @@ void CheckStl::checkMutexes()
             if (Token::Match(tok, "%var% . lock ( )")) {
                 if (!isMutex(var))
                     continue;
-                if (!var->isStatic() && var->scope() == tok->scope())
+                if (isLocalMutex(var, tok->scope()))
                     localMutexError(tok);
             } else if (Token::Match(tok, "%var% (|{ %var% )|}")) {
                 if (!isLockGuard(var))
@@ -2438,7 +2445,7 @@ void CheckStl::checkMutexes()
                 const Variable* mvar = tok->tokAt(2)->variable();
                 if (var->isStatic() || var->isGlobal())
                     globalLockGuardError(tok);
-                else if (mvar && !mvar->isStatic() && mvar->scope() == tok->scope())
+                else if (isLocalMutex(mvar, tok->scope()))
                     localMutexError(tok);
             }
         }
diff --git a/lib/token.cpp b/lib/token.cpp
index 1cd6c1a80..59e6dd57e 100644
--- a/lib/token.cpp
+++ b/lib/token.cpp
@@ -2086,6 +2086,8 @@ const ::Type *Token::typeOf(const Token *tok)
 
 std::pair<const Token*, const Token*> Token::typeDecl(const Token * tok)
 {
+    if (!tok)
+        return {};
     if (Token::simpleMatch(tok, "return")) {
         const Scope *scope = tok->scope();
         if (!scope)
@@ -2102,9 +2104,19 @@ std::pair<const Token*, const Token*> Token::typeDecl(const Token * tok)
             return {};
         if (!var->typeStartToken() || !var->typeEndToken())
             return {};
+        if (Token::simpleMatch(var->typeStartToken(), "auto")) {
+            const Token * tok2 = var->declEndToken();
+            if (Token::Match(tok2, "; %varid% =", var->declarationId()))
+                tok2 = tok2->tokAt(2);
+            if (Token::simpleMatch(tok2, "=") && tok2->astOperand2()) {
+                std::pair<const Token*, const Token*> r = typeDecl(tok2->astOperand2());
+                if (r.first)
+                    return r;
+            }
+        }
         return {var->typeStartToken(), var->typeEndToken()->next()};
-    } else if (Token::Match(tok, "%name%")) {
-        const Function *function = tok->function();
+    } else if (Token::Match(tok->previous(), "%name% (")) {
+        const Function *function = tok->previous()->function();
         if (!function)
             return {};
         return {function->retDef, function->returnDefEnd()};
diff --git a/test/testautovariables.cpp b/test/testautovariables.cpp
index 242bae115..18ababc8d 100644
--- a/test/testautovariables.cpp
+++ b/test/testautovariables.cpp
@@ -1986,8 +1986,9 @@ private:
               "    return get_default(m, k, &x);\n"
               "}\n",
               true);
-        ASSERT_EQUALS(
+        TODO_ASSERT_EQUALS(
             "[test.cpp:9] -> [test.cpp:9] -> [test.cpp:8] -> [test.cpp:9]: (error, inconclusive) Returning pointer to local variable 'x' that will be invalid when returning.\n",
+            "",
             errout.str());
 
         check("std::vector<int> g();\n"
diff --git a/test/teststl.cpp b/test/teststl.cpp
index 495dcff09..6d2fcb093 100644
--- a/test/teststl.cpp
+++ b/test/teststl.cpp
@@ -4485,6 +4485,44 @@ private:
               "};\n",
               true);
         ASSERT_EQUALS("[test.cpp:4]: (warning) The lock guard won't unlock until the end of the program which could lead to a deadlock.\n", errout.str());
+
+        check("std::mutex& h();\n"
+              "void f() {\n"
+              "    auto& m = h();\n"
+              "    std::lock_guard<std::mutex> g(m);\n"
+              "}\n",
+              true);
+        ASSERT_EQUALS("", errout.str());
+
+        check("void g();\n"
+              "std::mutex& h();\n"
+              "void f() {\n"
+              "    auto& m = h();\n"
+              "    m.lock();\n"
+              "    g();\n"
+              "    m.unlock();\n"
+              "}\n",
+              true);
+        ASSERT_EQUALS("", errout.str());
+
+        check("std::mutex& h();\n"
+              "void f() {\n"
+              "    auto m = h();\n"
+              "    std::lock_guard<std::mutex> g(m);\n"
+              "}\n",
+              true);
+        ASSERT_EQUALS("[test.cpp:4]: (warning) The lock is ineffective because the mutex is locked at the same scope as the mutex itself.\n", errout.str());
+
+        check("void g();\n"
+              "std::mutex& h();\n"
+              "void f() {\n"
+              "    auto m = h();\n"
+              "    m.lock();\n"
+              "    g();\n"
+              "    m.unlock();\n"
+              "}\n",
+              true);
+        ASSERT_EQUALS("[test.cpp:5]: (warning) The lock is ineffective because the mutex is locked at the same scope as the mutex itself.\n", errout.str());
     }
 };