Fmt: Introduce clang-format

[stryku]

It would be really helpful. I think there should be a .clang-format file created and a cf version mentioned in the CONTRIBUTING.rst

[luncliff]

Sounds reasonable. I've been using .clang-format something like below.

Following links will be helpful.

• Designing .clang-format : https://clangformat.com/
• Support in Visual Studio : https://blogs.msdn.microsoft.com/vcblog/2018/03/13/clangformat-support-in-visual-studio-2017-15-7-preview-1/
• Support in Visual Studio Code: https://code.visualstudio.com/docs/languages/cpp#_code-formatting

BasedOnStyle: Google
Language: Cpp
Standard: Cpp11

UseTab: Never
IndentWidth: 4
ColumnLimit: 80
PointerAlignment: Left

AlignTrailingComments: true
AllowShortFunctionsOnASingleLine: false
AllowShortIfStatementsOnASingleLine: false
AllowShortLoopsOnASingleLine: false
AlwaysBreakTemplateDeclarations: true 

BreakBeforeBinaryOperators: true
BreakBeforeBraces: Allman
BreakBeforeTernaryOperators: true

ConstructorInitializerAllOnOneLineOrOnePerLine: true
Cpp11BracedListStyle: true

IndentCaseLabels: false
IndentFunctionDeclarationAfterType: true
NamespaceIndentation: None

[foonathan]

I've run https://github.com/johnmcfarlane/unformat and it created the following .clang-format file. It only did some minor changes to format.h, I recommend you try it out @vitaut.
clang-format.txt

(Had to rename the file for github)

[DanielaE]

Jonathan's .clang-format can be simplified to just

BasedOnStyle: Google
AlwaysBreakTemplateDeclarations: true

Enjoy!

[vitaut]

Done in https://github.com/fmtlib/fmt/commit/58b6f8db48792a6f8b43a0b6caef1de5fac96f03.