Merge pull request #3952 from leoetlino/clangformat

Contributing: Update guide for clang-format

Contributing.md

@@ -24,35 +24,38 @@ This guide is for developers who wish to contribute to the Dolphin codebase. It
 
 Following this guide and formatting your code as detailed will likely get your pull request merged much faster than if you don't (assuming the written code has no mistakes in itself).
 
+This project uses clang-format (stable branch) to check for common style issues. In case of conflicts between this guide and clang-format rules, the latter should be followed instead of this guide.
+
+
+### Checking and fixing formatting issues
+
+In most cases, clang-format can and **should** be used to automatically reformat code and solve most formatting issues.
+
+- To run clang-format on all staged files:
+  ```
+  git diff --cached --name-only | egrep '[.](cpp|h|mm)$' | xargs clang-format -i
+  ```
+
+- Formatting issues can be checked for before committing with a lint script that is included with the codebase. To enable it as a pre-commit hook (assuming you are in the repository root):
+  ```
+  ln -s ../../Tools/lint.sh .git/hooks/pre-commit
+  ```
+
+- Alternatively, a custom git filter driver can be used to automatically and transparently reformat any changes:
+  ```
+  git config filter.clang_format.smudge 'cat'
+  git config filter.clang_format.clean 'clang-format %f'
+  echo '/Source/Core/**/*.cpp filter=clang_format' >> .git/info/attributes
+  echo '/Source/Core/**/*.h filter=clang_format' >> .git/info/attributes
+  echo '/Source/Core/**/*.mm filter=clang_format' >> .git/info/attributes
+  ```
+
 ## Styling and formatting
 
 ### General
 - Try to limit lines of code to a maximum of 100 characters.
     - Note that this does not mean you should try and use all 100 characters every time you have the chance. Typically with well formatted code, you normally shouldn't hit a line count of anything over 80 or 90 characters.
-- The indentation style we use is tabs for initial indentation and then, if vertical alignment is needed, spaces are to be used:
+- The indentation style we use is 2 spaces per level.
-```c++
-class IndentAndAlignmentSample
-{
-public:
-	void ThisMethodIsIndentedByOneLevel(int using_one_single_tab)
-	{
-		// this method, along with its opening and closing braces are
-		// indented with a single tab. This comment however is indented
-		// with two tabs. There is no vertical alignment yet, so no
-		// spaces are involved at this point.
-		m_other->DoStuff(m_first_parameter,
-		                 m_second_parameter,
-		                 m_third_parameter);
-		// Indent for the three previous lines is done using two tabs
-		// each (which brings the lines to the column where the word
-		// m_other begins in the first line).
-		// However, lines two and three are vertically aligned using
-		// 17 spaces (that's the length of "m_other->DoStuff(") in order
-		// to line up the method parameters correctly, regardless of
-		// tab-width settings used in your editor/IDE.
-	}
-}
-```
 - The opening brace for namespaces, classes, functions, enums, structs, unions, conditionals, and loops go on the next line.
   - With array initializer lists and lambda expressions it is OK to keep the brace on the same line.
 - References and pointers have the ampersand or asterisk against the type name, not the variable name. Example: `int* var`, not `int *var`.
@@ -166,9 +169,10 @@ private:
 - If a header is not necessary in a certain source file, remove them.
 - If you find duplicate includes of a certain header, remove it.
 - When declaring includes in a source file, make sure they follow the given pattern:
+  - The header for the source file
   - Standard library headers
   - System-specific headers (these should also likely be in an `#ifdef` block unless the source file itself is system-specific).
-  - Dolphin source file headers
+  - Other Dolphin source file headers
 - Each of the above header sections should also be in alphabetical order
 - Project source file headers should be included in a way that is relative to the `[Dolphin Root]/Source/Core` directory.
 - This project uses `#pragma once` as header guards.