[clang] 4c9d691 - clang-format: [JS] fix `??` opreator wrapping.

[Martin Probst via cfe-commits]

Author: Martin Probst
Date: 2020-01-20T17:07:14+01:00
New Revision: 4c9d6914453d970b7b8202b7efd7524b2f0a72ac

URL: https://github.com/llvm/llvm-project/commit/4c9d6914453d970b7b8202b7efd7524b2f0a72ac
DIFF: https://github.com/llvm/llvm-project/commit/4c9d6914453d970b7b8202b7efd7524b2f0a72ac.diff

LOG: clang-format: [JS] fix `??` opreator wrapping.

Summary:
clang-format currently treats the nullish coalescing operator `??` like
the ternary operator. That causes multiple nullish terms to be each
indented relative to the last `??`, as they would in a ternary.

The `??` operator is often used in chains though, and as such more
similar to other binary operators, such as `||`. So to fix the indent,
set its token type to `||`, so it inherits the same treatment.

This opens up the question of operator precedence. However, `??` is
required to be parenthesized when mixed with `||` and `&&`, so this is
not a problem that can come up in syntactically legal code.

Reviewers: krasimir

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D73026

Added: 
    

Modified: 
    clang/lib/Format/FormatTokenLexer.cpp
    clang/unittests/Format/FormatTestJS.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Format/FormatTokenLexer.cpp b/clang/lib/Format/FormatTokenLexer.cpp
index ef20ba884fb3..9c9fee2b0c32 100644
--- a/clang/lib/Format/FormatTokenLexer.cpp
+++ b/clang/lib/Format/FormatTokenLexer.cpp
@@ -120,8 +120,11 @@ void FormatTokenLexer::tryMergePreviousTokens() {
       Tokens.back()->Tok.setKind(tok::starequal);
       return;
     }
-    if (tryMergeTokens(JSNullishOperator, TT_JsNullishCoalescingOperator))
+    if (tryMergeTokens(JSNullishOperator, TT_JsNullishCoalescingOperator)) {
+      // Treat like the "||" operator (as opposed to the ternary ?).
+      Tokens.back()->Tok.setKind(tok::pipepipe);
       return;
+    }
     if (tryMergeTokens(JSNullPropagatingOperator,
                        TT_JsNullPropagatingOperator)) {
       // Treat like a regular "." access.

diff  --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
index ffeb53d9a33c..ef3c6361355a 100644
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -2294,6 +2294,11 @@ TEST_F(FormatTestJS, NullPropagatingOperator) {
 
 TEST_F(FormatTestJS, NullishCoalescingOperator) {
   verifyFormat("const val = something ?? 'some other default';\n");
+  verifyFormat(
+      "const val = something ?? otherDefault ??\n"
+      "    evenMore ?? evenMore;\n",
+      "const val = something ?? otherDefault ?? evenMore ?? evenMore;\n",
+      getGoogleJSStyleWithColumns(40));
 }
 
 TEST_F(FormatTestJS, Conditional) {