Fix GCC 4.7 warnings, which are related to char being signed in GCC

src/mksnapshot.cc

Index: src/mksnapshot.cc
===================================================================
--- src/mksnapshot.cc	(revision 10237)
+++ src/mksnapshot.cc	(working copy)
@@ -87,8 +87,8 @@
 class Compressor {
  public:
   virtual ~Compressor() {}
-  virtual bool Compress(i::Vector<char> input) = 0;
-  virtual i::Vector<char>* output() = 0;
+  virtual bool Compress(i::Vector<unsigned char> input) = 0;
+  virtual i::Vector<unsigned char>* output() = 0;
 };
 
 
@@ -112,7 +112,7 @@
       fprintf(fp, "%d", at(j));

[Vyacheslav Egorov (Chromium), 2011/12/12 18:06:17]

Instead of using unsigned char you can probably just add a cast from char to
unsigned char here. This will be a smaller yet more correct change (as it
conveys our intent directly --- we want all printed values to be positive).

What do you think?

[Tobias Burnus, 2011/12/12 21:54:00]

I agree that the patch will be shorter. I am not sure that it is more correct.
With the current patch, no cast is needed which I regard as more correct than
adding a cast. However, I am open for either solution.

     }
   }
-  char at(int i) { return data_[i]; }
+  unsigned char at(int i) { return data_[i]; }
   bool Compress(Compressor* compressor) {
     ASSERT_EQ(-1, raw_size_);
     raw_size_ = data_.length();
@@ -124,7 +124,7 @@
   int raw_size() { return raw_size_; }
 
  private:
-  i::List<char> data_;
+  i::List<unsigned char> data_;
   int raw_size_;
 };
 
@@ -232,9 +232,10 @@
   virtual ~BZip2Compressor() {
     delete output_;
   }
-  virtual bool Compress(i::Vector<char> input) {
+  virtual bool Compress(i::Vector<unsigned char> input) {
     delete output_;
-    output_ = new i::ScopedVector<char>((input.length() * 101) / 100 + 1000);
+    output_ = new i::ScopedVector<unsigned char>((input.length() * 101) / 100

[Vyacheslav Egorov (Chromium), 2011/12/12 18:06:17]

Usually we are leaving operation on the previous line.

You can break the line after >( if + does not fit.

+                                                 + 1000);
     unsigned int output_length_ = output_->length();
     int result = BZ2_bzBuffToBuffCompress(output_->start(), &output_length_,
                                           input.start(), input.length(),
@@ -247,10 +248,10 @@
       return false;
     }
   }
-  virtual i::Vector<char>* output() { return output_; }
+  virtual i::Vector<unsigned char>* output() { return output_; }
 
  private:
-  i::ScopedVector<char>* output_;
+  i::ScopedVector<unsigned char>* output_;
 };
 
 
@@ -259,7 +260,7 @@
   virtual ~BZip2Decompressor() { }
 
  protected:
-  virtual int DecompressData(char* raw_data,
+  virtual int DecompressData(unsigned char* raw_data,
                              int* raw_data_size,
                              const char* compressed_data,
                              int compressed_data_size) {
@@ -269,7 +270,7 @@
     int result =
         BZ2_bzBuffToBuffDecompress(raw_data,
                                    &decompressed_size,
-                                   const_cast<char*>(compressed_data),
+                                   const_cast<unsigned char*>(compressed_data),
                                    compressed_data_size,
                                    0, 1);
     if (result == BZ_OK) {