Fixed #2719 (Fix excessive false positives in include-file handling)

lib/preprocessor.cpp

@@ -1971,9 +1971,28 @@ void Preprocessor::handleIncludes(std::string &code, const std::string &filePath
     }
 }
 
+static bool missingIncludes[256];
+
 // Report that include is missing
 void Preprocessor::missingInclude(const std::string &filename, unsigned int linenr, const std::string &header, bool userheader)
 {
+    // FIXME: we need to check if this is a duplicate error. has it
+    // been reported already that this header is missing? This is not
+    // a trivial task because it must be thread safe and the code in the
+    // lib must be plain C++.
+
+    // A simple solution is to calculate a sum of the header name,
+    // if the same sum has been used before then bailout
+    {
+        unsigned char sum = 0;
+        for (unsigned int i = 0; i < header.size(); ++i)
+            sum += header[i];
+
+        if (missingIncludes[sum])
+            return;
+        missingIncludes[sum] = 1;
+    }
+
     std::list<ErrorLogger::ErrorMessage::FileLocation> locationList;
     if (!filename.empty())
     {