js-syntax-propertize: Disambiguate JS from JSX, fixing some indents

Fix some JSX indentation bugs:

- Bug#24896 / https://github.com/mooz/js2-mode/issues/389
- Bug#30225
- https://github.com/mooz/js2-mode/issues/459

* lisp/progmodes/js.el (js--dotted-captured-name-re)
(js--unary-keyword-re, js--unary-keyword-p)
(js--disambiguate-beginning-of-jsx-tag)
(js--disambiguate-end-of-jsx-tag)
(js--disambiguate-js-from-jsx): New variables and functions.

(js-syntax-propertize): Additionally clarify when syntax is JS so that
‘(with-syntax-table sgml-mode-syntax-table …)’ does not mistake some
JS punctuation syntax for SGML parenthesis syntax, namely ‘<’ and ‘>’.

* test/manual/indent/js-jsx-unclosed-2.js: Add additional test for
unary operator parsing.

1 files changed, 14 insertions, 0 deletions

diff --git a/test/manual/indent/js-jsx-unclosed-2.js b/test/manual/indent/js-jsx-unclosed-2.js
index 2d42cf70f84..8b6f33325d7 100644
--- a/test/manual/indent/js-jsx-unclosed-2.js
+++ b/test/manual/indent/js-jsx-unclosed-2.js
@@ -15,3 +15,17 @@ if (foo > bar) void 0
 // Don’t even misinterpret unary operators as JSX.
 if (foo < await bar) void 0
 while (await foo > bar) void 0
+
+// Allow unary keyword names as null-valued JSX attributes.
+// (As if this will EVER happen…)
+<Foo yield>
+  <Bar void>
+    <Baz
+      zorp
+      typeof>
+      <Please do_n0t delete this_stupidTest >
+        How would we ever live without unary support
+      </Please>
+    </Baz>
+  </Bar>
+</Foo>