r343179 - clang-format: [JS] conditional types.

[Martin Probst via cfe-commits]

Author: mprobst
Date: Wed Sep 26 23:48:13 2018
New Revision: 343179

URL: http://llvm.org/viewvc/llvm-project?rev=343179&view=rev
Log:
clang-format: [JS] conditional types.

Summary:
This change adds some rudimentary support for conditional types.
Specifically it avoids breaking before `extends` and `infer` keywords,
which are subject to Automatic Semicolon Insertion, so breaking before
them creates incorrect syntax.

The actual formatting of the type expression is odd, but there is as of
yet no clear idea on how to format these.

See https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-8.html#conditional-types.

Reviewers: krasimir

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D52536

Modified:
    cfe/trunk/lib/Format/FormatToken.h
    cfe/trunk/lib/Format/TokenAnnotator.cpp
    cfe/trunk/unittests/Format/FormatTestJS.cpp

Modified: cfe/trunk/lib/Format/FormatToken.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Format/FormatToken.h?rev=343179&r1=343178&r2=343179&view=diff
==============================================================================
--- cfe/trunk/lib/Format/FormatToken.h (original)
+++ cfe/trunk/lib/Format/FormatToken.h Wed Sep 26 23:48:13 2018
@@ -680,6 +680,7 @@ struct AdditionalKeywords {
     kw_function = &IdentTable.get("function");
     kw_get = &IdentTable.get("get");
     kw_import = &IdentTable.get("import");
+    kw_infer = &IdentTable.get("infer");
     kw_is = &IdentTable.get("is");
     kw_let = &IdentTable.get("let");
     kw_module = &IdentTable.get("module");
@@ -751,6 +752,7 @@ struct AdditionalKeywords {
   IdentifierInfo *kw_function;
   IdentifierInfo *kw_get;
   IdentifierInfo *kw_import;
+  IdentifierInfo *kw_infer;
   IdentifierInfo *kw_is;
   IdentifierInfo *kw_let;
   IdentifierInfo *kw_module;

Modified: cfe/trunk/lib/Format/TokenAnnotator.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Format/TokenAnnotator.cpp?rev=343179&r1=343178&r2=343179&view=diff
==============================================================================
--- cfe/trunk/lib/Format/TokenAnnotator.cpp (original)
+++ cfe/trunk/lib/Format/TokenAnnotator.cpp Wed Sep 26 23:48:13 2018
@@ -3088,6 +3088,12 @@ bool TokenAnnotator::canBreakBefore(cons
       return Style.BreakBeforeBinaryOperators != FormatStyle::BOS_None;
     if (Right.is(Keywords.kw_as))
       return false; // must not break before as in 'x as type' casts
+    if (Right.isOneOf(Keywords.kw_extends, Keywords.kw_infer)) {
+      // extends and infer can appear as keywords in conditional types:
+      //   https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-8.html#conditional-types
+      // do not break before them, as the expressions are subject to ASI.
+      return false;
+    }
     if (Left.is(Keywords.kw_as))
       return true;
     if (Left.is(TT_JsNonNullAssertion))

Modified: cfe/trunk/unittests/Format/FormatTestJS.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/unittests/Format/FormatTestJS.cpp?rev=343179&r1=343178&r2=343179&view=diff
==============================================================================
--- cfe/trunk/unittests/Format/FormatTestJS.cpp (original)
+++ cfe/trunk/unittests/Format/FormatTestJS.cpp Wed Sep 26 23:48:13 2018
@@ -2308,5 +2308,14 @@ TEST_F(FormatTestJS, ParameterNamingComm
   verifyFormat("callFoo(/*spaceAfterParameterNamingComment=*/ 1);");
 }
 
+TEST_F(FormatTestJS, ConditionalTypes) {
+  // Formatting below is not necessarily intentional, this just ensures that
+  // clang-format does not break the code.
+  verifyFormat( // wrap
+      "type UnionToIntersection<U> =\n"
+      "    (U extends any ? (k: U) => void :\n"
+      "                     never) extends((k: infer I) => void) ? I : never;");
+}
+
 } // end namespace tooling
 } // end namespace clang