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

llvm-svn: 196901

1 files changed, 5 insertions, 2 deletions

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index d22facb9220..b8905a9bfd3 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -1293,9 +1293,12 @@ bool TokenAnnotator::spaceRequiredBetween(const AnnotatedLine &Line,
     return Line.Type == LT_ObjCDecl ||
            Left.isOneOf(tok::kw_return, tok::kw_new, tok::kw_delete,
                         tok::semi) ||
-           (Style.SpaceAfterControlStatementKeyword &&
+           (Style.SpaceBeforeParens != FormatStyle::SBPO_Never &&
             Left.isOneOf(tok::kw_if, tok::kw_for, tok::kw_while, tok::kw_switch,
-                         tok::kw_catch));
+                         tok::kw_catch)) ||
+           (Style.SpaceBeforeParens == FormatStyle::SBPO_Always &&
+            Left.isOneOf(tok::identifier, tok::kw___attribute) &&
+            Line.Type != LT_PreprocessorDirective);
   }
   if (Left.is(tok::at) && Right.Tok.getObjCKeywordID() != tok::objc_not_keyword)
     return false;