Slightly modify the formatting rules for braced lists.

Basically, the new rule is: The opening "{" always has to be on the
same line as the first element if the braced list is nested
(e.g. in another braced list or in a function).

The solution that clang-format produces almost always adheres to this
rule anyway and this makes clang-format significantly faster for larger
lists. Added a test cases for the only exception I could find
(which doesn't seem to be very important at first sight).

llvm-svn: 182082

1 files changed, 10 insertions, 2 deletions

diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index 6966aabd696..3dd0002abb5 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -977,10 +977,18 @@ private:
 
   /// \brief Returns \c true, if a line break after \p State is allowed.
   bool canBreak(const LineState &State) {
-    if (!State.NextToken->CanBreakBefore &&
-        !(State.NextToken->is(tok::r_brace) &&
+    const AnnotatedToken &Current = *State.NextToken;
+    const AnnotatedToken &Previous = *Current.Parent;
+    if (!Current.CanBreakBefore &&
+        !(Current.is(tok::r_brace) &&
           State.Stack.back().BreakBeforeClosingBrace))
       return false;
+    // The opening "{" of a braced list has to be on the same line as the first
+    // element if it is nested in another braced init list or function call.
+    if (!Current.MustBreakBefore && Previous.is(tok::l_brace) &&
+        Previous.Parent &&
+        Previous.Parent->isOneOf(tok::l_brace, tok::l_paren, tok::comma))
+      return false;
     return !State.Stack.back().NoLineBreak;
   }