Support GNU style rule to put a space before opening parenthesis.
Summary:
The rule from the GNU style states:
"We find it easier to read a program when it has spaces before the open-parentheses and after the commas."
http://www.gnu.org/prep/standards/standards.html#index-spaces-before-open_002dparen
This patch makes clang-format adds an option to put spaces before almost all open parentheses, except the cases, where different behavior is dictated by the style rules or language syntax:
* preprocessor:
** function-like macro definitions can't have a space between the macro name and the parenthesis;
** `#if defined(...)` can have a space, but it seems, that it's more frequently used without a space in GCC, for example;
* never add spaces after unary operators;
* adding spaces between two opening parentheses is controlled with the `SpacesInParentheses` option;
* never add spaces between `[` and `(` (there's no option yet).
Reviewers: djasper
Reviewed By: djasper
CC: cfe-commits, klimek
Differential Revision: http://llvm-reviews.chandlerc.com/D2326
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@196901
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