From 765c1ace87eddc49ba3dcf81f00adcfad46f026e Mon Sep 17 00:00:00 2001
From: IOBYTE <reif@earthlink.net>
Date: Sat, 26 Dec 2020 07:45:17 -0500
Subject: [PATCH] fix #10008 (false negative: knownEmptyContainer with alias in
 namespace and "using namespace") (#2979)

---
 lib/tokenize.cpp           | 33 ++++++++++++++++++++-------------
 test/testsimplifyusing.cpp | 16 ++++++++++++++++
 test/teststl.cpp           | 11 +++++++++++
 3 files changed, 47 insertions(+), 13 deletions(-)

diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index a4a13d21a..0ef905e48 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -1696,8 +1696,10 @@ void Tokenizer::simplifyTypedef()
 
 namespace {
     struct ScopeInfo3 {
-        ScopeInfo3(const std::string &name_, const Token *bodyEnd_) : name(name_), bodyEnd(bodyEnd_) {}
+        ScopeInfo3(const std::string &name_, const Token *bodyStart_, const Token *bodyEnd_)
+            : name(name_), bodyStart(bodyStart_), bodyEnd(bodyEnd_) {}
         const std::string name;
+        const Token * const bodyStart;
         const Token * const bodyEnd;
         std::set<std::string> usingNamespaces;
     };
@@ -1716,6 +1718,9 @@ namespace {
     {
         if (!tok)
             return;
+        if (tok->str() == "{" && !scopeInfo->empty() && tok == scopeInfo->back().bodyStart)
+            return;
+
         while (tok->str() == "}" && !scopeInfo->empty() && tok == scopeInfo->back().bodyEnd)
             scopeInfo->pop_back();
         if (!Token::Match(tok, "namespace|class|struct|union %name% {|:|::|<")) {
@@ -1762,13 +1767,13 @@ namespace {
                             scope = tok1->strAt(-3) + " :: " + scope;
                             tok1 = tok1->tokAt(-2);
                         }
-                        scopeInfo->emplace_back(scope, tok->link());
+                        scopeInfo->emplace_back(scope, tok, tok->link());
                         added = true;
                     }
                 }
 
                 if (all && !added)
-                    scopeInfo->emplace_back("", tok->link());
+                    scopeInfo->emplace_back("", tok, tok->link());
             }
             return;
         }
@@ -1791,7 +1796,7 @@ namespace {
                 tok = tok->next();
         }
         if (tok && tok->str() == "{") {
-            scopeInfo->emplace_back(classname,tok->link());
+            scopeInfo->emplace_back(classname, tok, tok->link());
         }
     }
 
@@ -1878,14 +1883,16 @@ namespace {
             return true;
 
         // check using namespace
-        if (!scopeList1.back().usingNamespaces.empty()) {
-            if (qualification.empty()) {
-                if (scopeList1.back().usingNamespaces.find(scope) != scopeList1.back().usingNamespaces.end())
-                    return true;
-            } else {
-                for (auto ns : scopeList1.back().usingNamespaces) {
-                    if (scope == ns + " :: " + qualification)
+        for (std::list<ScopeInfo3>::const_reverse_iterator it = scopeList1.crbegin(); it != scopeList1.crend(); ++it) {
+            if (!it->usingNamespaces.empty()) {
+                if (qualification.empty()) {
+                    if (it->usingNamespaces.find(scope) != it->usingNamespaces.end())
                         return true;
+                } else {
+                    for (auto ns : it->usingNamespaces) {
+                        if (scope == ns + " :: " + qualification)
+                            return true;
+                    }
                 }
             }
         }
@@ -1945,7 +1952,7 @@ bool Tokenizer::simplifyUsing()
     };
     std::list<Using> usingList;
 
-    scopeList.emplace_back("", nullptr);
+    scopeList.emplace_back("", nullptr, nullptr);
 
     for (Token *tok = list.front(); tok; tok = tok->next()) {
         if (mErrorLogger && !list.getFiles().empty())
@@ -1975,7 +1982,7 @@ bool Tokenizer::simplifyUsing()
             continue;
 
         std::list<ScopeInfo3> scopeList1;
-        scopeList1.emplace_back("", nullptr);
+        scopeList1.emplace_back("", nullptr, nullptr);
         std::string name = tok->strAt(1);
         const Token *nameToken = tok->next();
         std::string scope = getScopeName(scopeList);
diff --git a/test/testsimplifyusing.cpp b/test/testsimplifyusing.cpp
index 60d1cd349..58eb8cfb9 100644
--- a/test/testsimplifyusing.cpp
+++ b/test/testsimplifyusing.cpp
@@ -75,6 +75,7 @@ private:
         TEST_CASE(simplifyUsing9388);
         TEST_CASE(simplifyUsing9518);
         TEST_CASE(simplifyUsing9757);
+        TEST_CASE(simplifyUsing10008);
     }
 
     std::string tok(const char code[], bool simplify = true, Settings::PlatformType type = Settings::Native, bool debugwarnings = true) {
@@ -647,6 +648,21 @@ private:
                            "switch ( type ) { } }";
         ASSERT_EQUALS(exp, tok(code, false));
     }
+
+    void simplifyUsing10008() {
+        const char code[] = "namespace ns {\n"
+                            "    using ArrayType = std::vector<int>;\n"
+                            "}\n"
+                            "using namespace ns;\n"
+                            "static void f() {\n"
+                            "    const ArrayType arr;\n"
+                            "}";
+        const char exp[] = "using namespace ns ; "
+                           "static void f ( ) { "
+                           "const std :: vector < int > arr ; "
+                           "}";
+        ASSERT_EQUALS(exp, tok(code, false));
+    }
 };
 
 REGISTER_TEST(TestSimplifyUsing)
diff --git a/test/teststl.cpp b/test/teststl.cpp
index 439e1a413..7db9d5c4f 100644
--- a/test/teststl.cpp
+++ b/test/teststl.cpp
@@ -4741,6 +4741,17 @@ private:
               "}\n",
               true);
         ASSERT_EQUALS("", errout.str());
+
+        check("namespace ns {\n"
+              "    using ArrayType = std::vector<int>;\n"
+              "}\n"
+              "using namespace ns;\n"
+              "static void f() {\n"
+              "    const ArrayType arr;\n"
+              "    for (const auto &a : arr) {}\n"
+              "}",
+              true);
+        ASSERT_EQUALS("[test.cpp:7]: (style) Iterating over container 'arr' that is always empty.\n", errout.str());
     }
 
     void checkMutexes() {