clang-format: Handle "if constexpr".

c++1z adds the following constructions to the language:

  if constexpr (cond)
    statement1;
  else if constexpr (cond)
    statement2;
  else if constexpr (cond)
    statement3;
  else
    statement4;

A first version of this was proposed in reviews.llvm.org/D26953 by
Francis Visoiu Mistrih, but never commited. This patch additionally
fixes the behavior when allowing short if statements on a single line
and was authored by Jacob Bandes-Storch. Thank you to both authors.

llvm-svn: 305666

1 files changed, 2 insertions, 1 deletions

diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index 387923031f8..bc8fe549954 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -453,7 +453,8 @@ void ContinuationIndenter::addTokenOnCurrentLine(LineState &State, bool DryRun,
   State.Column += Spaces;
   if (Current.isNot(tok::comment) && Previous.is(tok::l_paren) &&
       Previous.Previous &&
-      Previous.Previous->isOneOf(tok::kw_if, tok::kw_for)) {
+      (Previous.Previous->isOneOf(tok::kw_if, tok::kw_for) ||
+       Previous.Previous->endsSequence(tok::kw_constexpr, tok::kw_if))) {
     // Treat the condition inside an if as if it was a second function
     // parameter, i.e. let nested calls have a continuation indent.
     State.Stack.back().LastSpace = State.Column;