clang-format: [JS] improve calculateBraceType heuristic

Summary:

calculateBraceTypes decides for braced init for empty brace pairs ({}).
In context of a function declaration, this incorrectly classifies empty
function or method bodies as braced inits, leading to missing wraps:

    class C {
      foo() {}[bar]() {}
    }

Where code should have wrapped after "}", before "[". This change adds
another piece of contextual information in that braces following closing
parentheses must always be the opening braces of function blocks. This
fixes brace detection for methods immediately followed by brackets
(computed property declarations), but also curlies.

Reviewers: djasper

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D33714

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@304290 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Format/UnwrappedLineParser.cpp b/lib/Format/UnwrappedLineParser.cpp
index ae79ea5d8a66899bd89ecf53f5807aecaf2f1b64..eda7ef36434df05a4731b737884d87e5e7a7d2ab 100644 (file)
--- a/lib/Format/UnwrappedLineParser.cpp
+++ b/lib/Format/UnwrappedLineParser.cpp
@@ -360,16 +360,21 @@ void UnwrappedLineParser::calculateBraceTypes(bool ExpectClassBody) {
 
     switch (Tok->Tok.getKind()) {
     case tok::l_brace:
-      if (Style.Language == FormatStyle::LK_JavaScript && PrevTok &&
-          PrevTok->is(tok::colon))
-        // A colon indicates this code is in a type, or a braced list following
-        // a label in an object literal ({a: {b: 1}}).
-        // The code below could be confused by semicolons between the individual
-        // members in a type member list, which would normally trigger BK_Block.
-        // In both cases, this must be parsed as an inline braced init.
-        Tok->BlockKind = BK_BracedInit;
-      else
+      if (Style.Language == FormatStyle::LK_JavaScript && PrevTok) {
+        if (PrevTok->is(tok::colon))
+          // A colon indicates this code is in a type, or a braced list
+          // following a label in an object literal ({a: {b: 1}}). The code
+          // below could be confused by semicolons between the individual
+          // members in a type member list, which would normally trigger
+          // BK_Block. In both cases, this must be parsed as an inline braced
+          // init.
+          Tok->BlockKind = BK_BracedInit;
+        else if (PrevTok->is(tok::r_paren))
+          // `) { }` can only occur in function or method declarations in JS.
+          Tok->BlockKind = BK_Block;
+      } else {
         Tok->BlockKind = BK_Unknown;
+      }
       LBraceStack.push_back(Tok);
       break;
     case tok::r_brace:
@@ -391,6 +396,8 @@ void UnwrappedLineParser::calculateBraceTypes(bool ExpectClassBody) {
           // BlockKind later if we parse a braced list (where all blocks
           // inside are by default braced lists), or when we explicitly detect
           // blocks (for example while parsing lambdas).
+          // FIXME: Some of these do not apply to JS, e.g. "} {" can never be a
+          // braced list in JS.
           ProbablyBracedList =
               (Style.Language == FormatStyle::LK_JavaScript &&
                NextTok->isOneOf(Keywords.kw_of, Keywords.kw_in,

diff --git a/unittests/Format/FormatTestJS.cpp b/unittests/Format/FormatTestJS.cpp
index d8f887f9c788a7b694a006779ef704cc24210280..92a113111b6a7ff6f81c9ba0926bd4e195fbabd1 100644 (file)
--- a/unittests/Format/FormatTestJS.cpp
+++ b/unittests/Format/FormatTestJS.cpp
@@ -474,9 +474,8 @@ TEST_F(FormatTestJS, FormatsFreestandingFunctions) {
                "(function f() {\n"
                "  var x = 1;\n"
                "}());\n");
-  // Known issue: this should wrap after {}, but calculateBraceTypes
-  // misclassifies the first braces as a BK_BracedInit.
-  verifyFormat("function aFunction(){} {\n"
+  verifyFormat("function aFunction() {}\n"
+               "{\n"
                "  let x = 1;\n"
                "  console.log(x);\n"
                "}\n");
@@ -1233,6 +1232,10 @@ TEST_F(FormatTestJS, ClassDeclarations) {
   verifyFormat("class C {\n  x: string = 12;\n}");
   verifyFormat("class C {\n  x(): string => 12;\n}");
   verifyFormat("class C {\n  ['x' + 2]: string = 12;\n}");
+  verifyFormat("class C {\n"
+               "  foo() {}\n"
+               "  [bar]() {}\n"
+               "}\n");
   verifyFormat("class C {\n  private x: string = 12;\n}");
   verifyFormat("class C {\n  private static x: string = 12;\n}");
   verifyFormat("class C {\n  static x(): string {\n    return 'asd';\n  }\n}");