[clang-format] Add ability to wrap braces after multi-line control statements

Summary:
Change the BraceWrappingFlags' AfterControlStatement from a bool to an enum with three values:

* "Never": This is the default, and does not do any brace wrapping after control statements.
* "MultiLine": This only wraps braces after multi-line control statements (this really only happens when a ColumnLimit is specified).
* "Always": This always wraps braces after control statements.

The first and last options are backwards-compatible with "false" and "true", respectively.

The new "MultiLine" option is useful for when a wrapped control statement's indentation matches the subsequent block's indentation. It makes it easier to see at a glance where the control statement ends and where the block's code begins. For example:

```
if (
  foo
  && bar )
{
  baz();
}
```

vs.

```
if (
  foo
  && bar ) {
  baz();
}
```

Short control statements (1 line) do not wrap the brace to the next line, e.g.

```
if (foo) {
  bar();
} else {
  baz();
}
```

Reviewers: sammccall, owenpan, reuk, MyDeveloperDay, klimek

Reviewed By: MyDeveloperDay

Subscribers: MyDeveloperDay, cfe-commits

Patch By: mitchell-stellar

Tags: #clang-format, #clang, #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D68296

llvm-svn: 373647

1 files changed, 6 insertions, 3 deletions

diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index 8fd0e9433b6..bbe05602f6d 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -1167,7 +1167,8 @@ void UnwrappedLineParser::parseStructuralElement() {
       case tok::objc_autoreleasepool:
         nextToken();
         if (FormatTok->Tok.is(tok::l_brace)) {
-          if (Style.BraceWrapping.AfterControlStatement)
+          if (Style.BraceWrapping.AfterControlStatement ==
+              FormatStyle::BWACS_Always)
             addUnwrappedLine();
           parseBlock(/*MustBeDeclaration=*/false);
         }
@@ -1179,7 +1180,8 @@ void UnwrappedLineParser::parseStructuralElement() {
           // Skip synchronization object
           parseParens();
         if (FormatTok->Tok.is(tok::l_brace)) {
-          if (Style.BraceWrapping.AfterControlStatement)
+          if (Style.BraceWrapping.AfterControlStatement ==
+              FormatStyle::BWACS_Always)
             addUnwrappedLine();
           parseBlock(/*MustBeDeclaration=*/false);
         }
@@ -1989,7 +1991,8 @@ void UnwrappedLineParser::parseLabel(bool LeftAlignLabel) {
                                        Style.BraceWrapping.IndentBraces);
     parseBlock(/*MustBeDeclaration=*/false);
     if (FormatTok->Tok.is(tok::kw_break)) {
-      if (Style.BraceWrapping.AfterControlStatement)
+      if (Style.BraceWrapping.AfterControlStatement ==
+          FormatStyle::BWACS_Always)
         addUnwrappedLine();
       parseStructuralElement();
     }