From 3f1ab5af9b7ff3753624302e9b591053b13d4f97 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <danielm77@spray.se>
Date: Sat, 10 Mar 2012 12:19:28 +0100
Subject: [PATCH] charvar: dont write warning about char type array index when
 array is small and the full valid range is accessible with the char type. If
 there are out of bounds access then, it is not because the type of the
 variable.

---
 lib/checkother.cpp   |  6 ++++--
 test/testcharvar.cpp | 42 +++++++++++++++++++++++++++++++++++-------
 2 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/lib/checkother.cpp b/lib/checkother.cpp
index 9a8bd4a64..61c750c83 100644
--- a/lib/checkother.cpp
+++ b/lib/checkother.cpp
@@ -2032,8 +2032,10 @@ void CheckOther::checkCharVariable()
 
     for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next()) {
         if ((tok->str() != ".") && Token::Match(tok->next(), "%var% [ %var% ]")) {
-            const Variable* var = symbolDatabase->getVariableFromVarId(tok->tokAt(3)->varId());
-            if (isSignedChar(var))
+            const Variable* arrayvar = symbolDatabase->getVariableFromVarId(tok->next()->varId());
+            const Variable* indexvar = symbolDatabase->getVariableFromVarId(tok->tokAt(3)->varId());
+            const MathLib::bigint arraysize = (arrayvar && arrayvar->isArray()) ? arrayvar->dimension(0U) : 0;
+            if (isSignedChar(indexvar) && arraysize > 0x80)
                 charArrayIndexError(tok->next());
         }
 
diff --git a/test/testcharvar.cpp b/test/testcharvar.cpp
index b2cc85b0b..245a475c4 100644
--- a/test/testcharvar.cpp
+++ b/test/testcharvar.cpp
@@ -35,6 +35,7 @@ private:
     void run() {
         TEST_CASE(array_index_1);
         TEST_CASE(array_index_2);
+        TEST_CASE(array_index_3);
         TEST_CASE(bitop1);
         TEST_CASE(bitop2);
         TEST_CASE(bitop3);
@@ -62,32 +63,36 @@ private:
     }
 
     void array_index_1() {
-        check("void foo()\n"
+        check("int buf[256];\n"
+              "void foo()\n"
               "{\n"
               "    unsigned char ch = 0x80;\n"
               "    buf[ch] = 0;\n"
               "}\n");
         ASSERT_EQUALS("", errout.str());
 
-        check("void foo()\n"
+        check("int buf[256];\n"
+              "void foo()\n"
               "{\n"
               "    char ch = 0x80;\n"
               "    buf[ch] = 0;\n"
               "}\n");
-        ASSERT_EQUALS("[test.cpp:4]: (warning) Using char type as array index\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:5]: (warning) Using char type as array index\n", errout.str());
 
-        check("void foo()\n"
+        check("int buf[256];\n"
+              "void foo()\n"
               "{\n"
               "    signed char ch = 0x80;\n"
               "    buf[ch] = 0;\n"
               "}\n");
-        ASSERT_EQUALS("[test.cpp:4]: (warning) Using char type as array index\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:5]: (warning) Using char type as array index\n", errout.str());
 
-        check("void foo(char ch)\n"
+        check("int buf[256];\n"
+              "void foo(char ch)\n"
               "{\n"
               "    buf[ch] = 0;\n"
               "}\n");
-        ASSERT_EQUALS("[test.cpp:3]: (warning) Using char type as array index\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:4]: (warning) Using char type as array index\n", errout.str());
 
         check("void foo(const char str[])\n"
               "{\n"
@@ -106,6 +111,29 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void array_index_3() {
+        // only write error message when array is more than
+        // 0x80 elements in size. Otherwise the full valid
+        // range is accessible with a char.
+
+        check("char buf[0x81];\n"
+              "void bar(char c) {\n"
+              "    buf[c] = 0;\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:3]: (warning) Using char type as array index\n", errout.str());
+
+        check("char buf[0x80];\n"
+              "void bar(char c) {\n"
+              "    buf[c] = 0;\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+
+        check("void bar(char c) {\n"
+              "    buf[c] = 0;\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void bitop1() {
         check("void foo()\n"
               "{\n"