Resolving Merge Conflicts in Ogre-Next 3.0

In Ogre-Next 3.0 we performed multiple changes that affected nearly the entire code base in subtle ways:

• Codebase was C++11-fied (e.g. added override and final keywords)
• SharedPtr was replaced with std::shared_ptr and lots of its code was deprecated
• Lots of warnings were fixed
• Clang format 13 was applied to the entire codebase

Users who run a forked/customized version of Ogre-Next may found rebasing to the latest version a near impossible job due to the sheer amount of minor merge conflicts.

To perform this task more easily, we recommend the following:

1. Merge your changes with master branch (or 3.0 when it appears)
2. Resolve all conflicts with your code
3. Apply clang-format-13 again
4. Inspect the diff again to check for any auto-merge mistakes and fix them
5. Rebuild code to ensure it still compiles and runs
6. Commit

Now you have your changes applied on top of Ogre-Next 3.0!

Notes:

We're using clang-format-13

A common issue is that auto-merging will skip either an opening or closing brace (i.e. missing { or })

If you know what to look for, you can spot this quite easily thanks to clang format. Let say the following code:

void myFuntion( int a )
{
    for( int i = 0; i < count; ++i )
    {
        if( condition )
        {
            anotherFunction( a );
        }
    }
}
 
void anotherFunction( int a );
void run();
void moreFunctions()
{
    int abc = 0;
}

Got merged with but now a } is missing:

void myFuntion( int a )
{
    for( int i = 0; i < count; ++i )
    {
        if( condition )
        {
            anotherFunction( a );
        }
}
 
void anotherFunction( int a );
void run();
void moreFunctions()
{
    int abc = 0;
}

After applying Clang format, everything that follows will indent (and likely the code will not compile) which make much easier to spot where the problem went wrong:

void myFuntion( int a )
{
    for( int i = 0; i < count; ++i )
    {
        if( condition )
        {
            anotherFunction( a );
        }
    }
 
    void anotherFunction( int a );
    void run();
    void moreFunctions()
    {
        int abc = 0;
    }

If you find after merging and applying clang format that there is massive indentation being added (or removed); start from the top and find the first occurrence of this change and start looking for the missing brace.

Batch Script

The following bash script will run clang-format on all files with the right extensions in the current folder and recursively in its sub-directories.

FILES=$(find . -name "*.mm" -o -name "*.h" -o -name "*.cpp")
 
for file in $FILES
do
  echo "Formatting \"$file\""
  clang-format-13 -i "$file"
done

You can also look at our python script in .github/workflows/run_clang_format.py if you prefer Python instead.