[clang-format] Fix putting ObjC message arguments in one line for multiline receiver

Summary:
Currently BreakBeforeParameter is set to true everytime message receiver spans multiple lines, e.g.:
```
[[object block:^{
  return 42;
}] aa:42 bb:42];
```
will be formatted:
```
[[object block:^{
  return 42;
}] aa:42
   bb:42];
```
even though arguments could fit into one line. This change fixes this behavior.

Test Plan:
make -j12 FormatTests && tools/clang/unittests/Format/FormatTests

Reviewers: benhamilton, djasper

Reviewed By: benhamilton

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D46879

llvm-svn: 332582

1 files changed, 27 insertions, 1 deletions

diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index 9a07c5ed591..fc4c9115e89 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -1073,8 +1073,34 @@ unsigned ContinuationIndenter::moveStateToNextToken(LineState &State,
   if (Current.isMemberAccess())
     State.Stack.back().StartOfFunctionCall =
         !Current.NextOperator ? 0 : State.Column;
-  if (Current.is(TT_SelectorName))
+  if (Current.is(TT_SelectorName) &&
+      !State.Stack.back().ObjCSelectorNameFound) {
     State.Stack.back().ObjCSelectorNameFound = true;
+
+    // Reevaluate whether ObjC message arguments fit into one line.
+    // If a receiver spans multiple lines, e.g.:
+    //   [[object block:^{
+    //     return 42;
+    //   }] a:42 b:42];
+    // BreakBeforeParameter is calculated based on an incorrect assumption
+    // (it is checked whether the whole expression fits into one line without
+    // considering a line break inside a message receiver).
+    if (Current.Previous && Current.Previous->closesScope() &&
+        Current.Previous->MatchingParen &&
+        Current.Previous->MatchingParen->Previous) {
+      const FormatToken &CurrentScopeOpener =
+          *Current.Previous->MatchingParen->Previous;
+      if (CurrentScopeOpener.is(TT_ObjCMethodExpr) &&
+          CurrentScopeOpener.MatchingParen) {
+        int NecessarySpaceInLine =
+            getLengthToMatchingParen(CurrentScopeOpener, State.Stack) +
+            CurrentScopeOpener.TotalLength - Current.TotalLength - 1;
+        if (State.Column + Current.ColumnWidth + NecessarySpaceInLine <=
+            Style.ColumnLimit)
+          State.Stack.back().BreakBeforeParameter = false;
+      }
+    }
+  }
   if (Current.is(TT_CtorInitializerColon) &&
       Style.BreakConstructorInitializers != FormatStyle::BCIS_AfterColon) {
     // Indent 2 from the column, so: