From cb7757f6507e56fe0febddb5f8cf4e4dea68598e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Thu, 28 Jun 2012 17:22:56 +0200
Subject: [PATCH] CheckUnusedVar: dont report false positives for extern
 variables

---
 lib/checkunusedvar.cpp | 2 +-
 test/testunusedvar.cpp | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/lib/checkunusedvar.cpp b/lib/checkunusedvar.cpp
index 7be6cf3c7..8e7cb0971 100644
--- a/lib/checkunusedvar.cpp
+++ b/lib/checkunusedvar.cpp
@@ -597,7 +597,7 @@ void CheckUnusedVar::checkFunctionVariableUsage_iterateScopes(const Scope* const
     if (scope->type != Scope::eClass && scope->type != Scope::eUnion && scope->type != Scope::eStruct) {
         // Find declarations
         for (std::list<Variable>::const_iterator i = scope->varlist.begin(); i != scope->varlist.end(); ++i) {
-            if (i->isThrow())
+            if (i->isThrow() || i->isExtern())
                 continue;
             Variables::VariableType type = Variables::none;
             if (i->isArray() && (i->nameToken()->previous()->str() == "*" || i->nameToken()->strAt(-2) == "*"))
diff --git a/test/testunusedvar.cpp b/test/testunusedvar.cpp
index f340d58e8..16c65aae5 100644
--- a/test/testunusedvar.cpp
+++ b/test/testunusedvar.cpp
@@ -102,6 +102,7 @@ private:
         TEST_CASE(localvaralias10); // ticket #2004
         TEST_CASE(localvarasm);
         TEST_CASE(localvarstatic);
+        TEST_CASE(localvarextern);
         TEST_CASE(localvardynamic1);
         TEST_CASE(localvardynamic2); // ticket #2904
         TEST_CASE(localvardynamic3); // ticket #3467
@@ -2793,6 +2794,14 @@ private:
         ASSERT_EQUALS("[test.cpp:4]: (style) Variable 'b' is assigned a value that is never used\n", errout.str());
     }
 
+    void localvarextern() {
+        functionVariableUsage("void foo() {\n"
+                              "    extern int i;\n"
+                              "    i = 0;\n"
+                              "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void localvardynamic1() {
         functionVariableUsage("void foo()\n"
                               "{\n"