Description

Closes #19203.

When !default or !global appeared inside a string or function argument in SCSS, Prettier treated it as a Sass declaration flag and split it off the value, injecting a stray space:

/* input */
$a: "!default";
$b: unquote("!default");
$c: url("x!global");

/* output before this PR */
$a: " !default";
$b: unquote(" !default");
$c: url("x !global");

Cause

The flag was detected with value.match(/(\s*)(!default).*$/), which matches the raw !default / !global text anywhere in the value — including inside strings and url(...) / function arguments — and then sliced everything after it off the value.

Fix

Detect the directive structurally. A genuine trailing flag parses as the final top-level value-word node whose value is exactly !default / !global (optionally followed only by comments). Text inside a string parses as a value-string, and text inside a function parses as a value-func, so those are correctly left untouched. The comma-separated case (where the flag lives in the last comma item) is handled too. If the value can't be parsed structurally, it falls back to the original regex so existing behavior is preserved.

/* output after this PR */
$a: "!default";
$b: unquote("!default");
$c: url("x!global");

/* genuine flags still work, including alongside a string value */
$d: "!default" !default;
$e: "x!global" !global;
$f: map-get($map, "!default") !default;

Checklist

• Added a regression fixture (tests/format/scss/flag/19203.scss) covering in-string, function-argument, and mixed string-plus-genuine-flag cases.
• yarn jest tests/format/scss tests/format/css tests/format/less passes (358/358).
• yarn eslint src/language-css/parser-postcss.js passes.
• yarn lint:prettier passes.