2 files changed, 66 insertions, 0 deletions
diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index 0862a4e0f95..90d2a999711 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -1398,6 +1398,30 @@ void ContinuationIndenter::moveStatePastScopeCloser(LineState &State) {
        (Current.is(tok::greater) && Current.is(TT_DictLiteral))))
     State.Stack.pop_back();
 
+  // 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).
+  // We check whether arguements fit after receiver scope closer (into the same
+  // line).
+  if (State.Stack.back().BreakBeforeParameter && Current.MatchingParen &&
+      Current.MatchingParen->Previous) {
+    const FormatToken &CurrentScopeOpener = *Current.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(tok::r_square)) {
     // If this ends the array subscript expr, reset the corresponding value.
     const FormatToken *NextNonComment = Current.getNextNonComment();
diff --git a/clang/unittests/Format/FormatTestObjC.cpp b/clang/unittests/Format/FormatTestObjC.cpp
index 58e75363a55..e56df6d130d 100644
--- a/clang/unittests/Format/FormatTestObjC.cpp
+++ b/clang/unittests/Format/FormatTestObjC.cpp
@@ -820,6 +820,48 @@ TEST_F(FormatTestObjC, FormatObjCMethodExpr) {
   verifyFormat("aaaaaa = [aa aa:aa\n"
                "             aa:aa];");
 
+  // Message receiver taking multiple lines.
+  // Non-corner case.
+  verifyFormat("[[object block:^{\n"
+               "  return 42;\n"
+               "}] a:42 b:42];");
+  // Arguments just fit into one line.
+  verifyFormat("[[object block:^{\n"
+               "  return 42;\n"
+               "}] aaaaaaa:42 b:42];");
+  // Arguments just over a column limit.
+  verifyFormat("[[object block:^{\n"
+               "  return 42;\n"
+               "}] aaaaaaa:42\n"
+               "        bb:42];");
+  // Arguments just fit into one line.
+  Style.ColumnLimit = 23;
+  verifyFormat("[[obj a:42\n"
+               "      b:42\n"
+               "      c:42\n"
+               "      d:42] e:42 f:42];");
+
+  // Arguments do not fit into one line with a receiver.
+  Style.ColumnLimit = 20;
+  verifyFormat("[[obj a:42] a:42\n"
+               "            b:42];");
+  verifyFormat("[[obj a:42] a:42\n"
+               "            b:42\n"
+               "            c:42];");
+  verifyFormat("[[obj aaaaaa:42\n"
+               "           b:42]\n"
+               "    cc:42\n"
+               "     d:42];");
+
+  // Avoid breaking receiver expression.
+  Style.ColumnLimit = 30;
+  verifyFormat("fooooooo =\n"
+               "    [[obj fooo] aaa:42\n"
+               "                aaa:42];");
+  verifyFormat("[[[obj foo] bar] aa:42\n"
+               "                 bb:42\n"
+               "                 cc:42];");
+
   Style.ColumnLimit = 70;
   verifyFormat(
       "void f() {\n"