clang-format: [JS] Prevent ASI before [ and (.

Summary:
JavaScript automatic semicolon insertion can trigger before [ and (, so
avoid breaking before them if the previous token is likely to terminate
an expression.

Reviewers: djasper

Subscribers: cfe-commits, klimek

Differential Revision: https://reviews.llvm.org/D42570

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@323532 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Format/TokenAnnotator.cpp

@@ -2710,9 +2710,11 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
             Keywords.kw_readonly, Keywords.kw_abstract, Keywords.kw_get,
             Keywords.kw_set, Keywords.kw_async, Keywords.kw_await))
       return false; // Otherwise automatic semicolon insertion would trigger.
-    if (Left.Tok.getIdentifierInfo() &&
-        Right.startsSequence(tok::l_square, tok::r_square))
-      return false;  // breaking in "foo[]" creates illegal TS type syntax.
+    if (Right.NestingLevel == 0 &&
+        (Left.Tok.getIdentifierInfo() ||
+         Left.isOneOf(tok::r_square, tok::r_paren)) &&
+        Right.isOneOf(tok::l_square, tok::l_paren))
+      return false; // Otherwise automatic semicolon insertion would trigger.
     if (Left.is(TT_JsFatArrow) && Right.is(tok::l_brace))
       return false;
     if (Left.is(TT_JsTypeColon))

unittests/Format/FormatTestJS.cpp

@@ -1157,6 +1157,9 @@ TEST_F(FormatTestJS, WrapRespectsAutomaticSemicolonInsertion) {
                "foo() {}",
                getGoogleJSStyleWithColumns(10));
   verifyFormat("await theReckoning;", getGoogleJSStyleWithColumns(10));
+  verifyFormat("some['a']['b']", getGoogleJSStyleWithColumns(10));
+  verifyFormat("x = (a['a']\n"
+               "      ['b']);", getGoogleJSStyleWithColumns(10));
 }
 
 TEST_F(FormatTestJS, AutomaticSemicolonInsertionHeuristic) {