clang-format: [JS] handle semis in generic types.

Summary:
TypeScript generic type arguments can contain object (literal) types,
which in turn can contain semicolons:

    const x: Array<{a: number; b: string;} = [];

Previously, clang-format would incorrectly categorize the braced list as
a block and terminate the line at the openening `{`, and then format the
entire expression badly.

With this change, clang-format recognizes `<` preceding a `{` as
introducing a type expression. In JS, `<` comparison with an object
literal can never be true, so the chance of introducing false positives
here is very low.

Reviewers: djasper

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D40424

llvm-svn: 318975

1 files changed, 1 insertions, 0 deletions

diff --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
index cfdd4b375b6..187b50221d1 100644
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -1414,6 +1414,7 @@ TEST_F(FormatTestJS, TypeAnnotations) {
   verifyFormat("function x(y: {a?: number;} = {}): number {\n"
                "  return 12;\n"
                "}");
+  verifyFormat("const x: Array<{a: number; b: string;}> = [];");
   verifyFormat("((a: string, b: number): string => a + b);");
   verifyFormat("var x: (y: number) => string;");
   verifyFormat("var x: P<string, (a: number) => string>;");