Fix some GCC warnings regarding the sign conversion.

cli/cppcheckexecutor.cpp

@@ -26,6 +26,7 @@
 #include <cstdlib> // EXIT_SUCCESS and EXIT_FAILURE
 #include <cstring>
 #include <algorithm>
+#include <climits>
 
 #include "cmdlineparser.h"
 #include "filelister.h"
@@ -106,7 +107,7 @@ bool CppCheckExecutor::parseFromArgs(CppCheck *cppcheck, int argc, const char* c
         bool warned = false;
         std::vector<std::string> ignored = parser.GetIgnoredPaths();
         std::vector<std::string>::iterator iterIgnored = ignored.begin();
-        for (int i = (int)ignored.size() - 1; i >= 0; i--) {
+        for (unsigned int i = ignored.size() - 1; i != UINT_MAX; --i) {
             const std::string extension = Path::getFilenameExtension(ignored[i]);
             if (extension == ".h" || extension == ".hpp") {
                 ignored.erase(iterIgnored + i);
@@ -120,14 +121,14 @@ bool CppCheckExecutor::parseFromArgs(CppCheck *cppcheck, int argc, const char* c
 
         PathMatch matcher(parser.GetIgnoredPaths());
         std::vector<std::string>::iterator iterBegin = filenames.begin();
-        for (int i = (int)filenames.size() - 1; i >= 0; i--) {
+        for (unsigned int i = filenames.size() - 1; i != UINT_MAX; i--) {
 #if defined(_WIN32)
             // For Windows we want case-insensitive path matching
             const bool caseSensitive = false;
 #else
             const bool caseSensitive = true;
 #endif
-            if (matcher.Match(filenames[(unsigned int)i], caseSensitive))
+            if (matcher.Match(filenames[i], caseSensitive))
                 filenames.erase(iterBegin + i);
         }
     } else {

lib/checkbufferoverrun.cpp

@@ -1212,7 +1212,7 @@ void CheckBufferOverrun::checkScope(const Token *tok, const ArrayInfo &arrayInfo
 
 void CheckBufferOverrun::checkReadlinkBufferUsage(const Token* tok, const Token *scope_begin, const MathLib::bigint total_size, const bool is_readlinkat)
 {
-    unsigned int param_offset = is_readlinkat ? 2 : 0;
+    unsigned char param_offset = is_readlinkat ? 2 : 0;
     const std::string funcname = is_readlinkat ? "readlinkat" : "readlink";
 
     const MathLib::bigint n = MathLib::toLongNumber(tok->strAt(6 + param_offset));

lib/checkclass.cpp

@@ -1353,24 +1353,24 @@ bool CheckClass::isMemberVar(const Scope *scope, const Token *tok)
     return false;
 }
 
-static int countParameters(const Token *tok)
+static unsigned int countParameters(const Token *tok)
 {
     if (Token::Match(tok->tokAt(2), "void| )"))
         return 0;
 
-    int numpar = 1;
-    int parlevel = 0;
+    unsigned int numpar = 1;
+    unsigned int parlevel = 0;
     for (; tok; tok = tok->next()) {
         if (tok->str() == "(")
             ++parlevel;
 
         else if (tok->str() == ")") {
-            if (parlevel <= 1)
+            if (!parlevel)
                 break;
             --parlevel;
         }
 
-        else if (parlevel == 1 && tok->str() == ",") {
+        else if (!parlevel && tok->str() == ",") {
             ++numpar;
         }
     }

lib/checkinternal.cpp

@@ -82,7 +82,7 @@ void CheckInternal::checkTokenSimpleMatchPatterns()
         // Check for [xyz] usage - but exclude standalone square brackets
         unsigned int char_count = 0;
         for (string::size_type pos = 0; pos < pattern.size(); ++pos) {
-            unsigned char c = pattern[pos];
+            char c = pattern[pos];
 
             if (c == ' ') {
                 char_count = 0;
@@ -99,7 +99,7 @@ void CheckInternal::checkTokenSimpleMatchPatterns()
         // Check | usage: Count characters before the symbol
         char_count = 0;
         for (string::size_type pos = 0; pos < pattern.size(); ++pos) {
-            unsigned char c = pattern[pos];
+            char c = pattern[pos];
 
             if (c == ' ') {
                 char_count = 0;

lib/checkstl.cpp

@@ -1075,8 +1075,8 @@ void CheckStl::string_c_strError(const Token *tok)
 //---------------------------------------------------------------------------
 void CheckStl::checkAutoPointer()
 {
-    std::set<int> autoPtrVarId;
-    std::set<int>::const_iterator iter;
+    std::set<unsigned int> autoPtrVarId;
+    std::set<unsigned int>::const_iterator iter;
     static const char STL_CONTAINER_LIST[] = "bitset|deque|list|map|multimap|multiset|priority_queue|queue|set|stack|hash_map|hash_multimap|hash_set|vector";
 
     for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next()) {

lib/tokenize.cpp

@@ -956,7 +956,7 @@ void Tokenizer::simplifyTypedef()
         Token *argFuncRetEnd = 0;
         Token *funcStart = 0;
         Token *funcEnd = 0;
-        unsigned int offset = 1;
+        unsigned short offset = 1;
         bool function = false;
         bool functionPtr = false;
         bool functionRef = false;

tools/dmake.cpp

@@ -210,9 +210,10 @@ int main(int argc, char **argv)
         makeConditionalVariable(fout, "CXXFLAGS", "-O2 -DNDEBUG -Wall");
     } else {
         // TODO: add more compiler warnings.
-        // -Wlogical-op      : doesn't work on older GCC
-        // -Wconversion      : too many warnings
-        // -Wsign-conversion : too many warnings
+        // -Wlogical-op       : doesn't work on older GCC
+        // -Wconversion       : too many warnings
+        // -Wsign-conversion  : too many warnings
+        // -Wunreachable-code : some GCC versions report lots of warnings
 
         // The _GLIBCXX_DEBUG doesn't work in cygwin
         makeConditionalVariable(fout, "CXXFLAGS",