TypeScript/tests/cases/compiler/doubleUnderscoreLabels.ts

function doThing() {
    __call: while (true) {
        aLabel: for (let i = 0; i < 10; i++) {
            if (i === 3) {
                break __call;
            }
            if (i === 5) {
                break aLabel;
            }
        }
    }
}
doThing();
Created a branded type for identifier-escaped strings (#16915) * Created a branded type for escaped strings Then flowed it throughout the compiler, finding and fixing a handful of bugs relating to underscore-prefixed identifiers in the process. Includes a test for two cases noticed - diagnostics from conflicting symbols from export 's, and enum with underscore prefixed member emit. Correctly double underscores WRT mapped types * Add fourslash tests for other fixed issues * use function call over cast * Update forEachEntry type accuracy * Just use escaped names for ActiveLabel * Remove casts from getPropertyNameForPropertyNameNode * This pattern has occurred a few times, could use a helper function. * Remove duplicated helper * Remove unneeded check, use helper * Identifiers list is no longer escaped strings * Extract repeated string-getting code into helper * Rename type and associated functions * Make getName() return UnderscoreEscapedString, add getUnescapedName() * Add list of internal symbol names to escaped string type to cut back on casting * Remove outdated comments * Reassign interned values to nodes, just in case * Swap to string enum * Add deprecated aliases to escapeIdentifier and unescapeIdentifier * Add temp var * Remove unsafe casts * Rename escaped string type as per @sandersn's suggestion, fix string enum usages * Reorganize double underscore tests * Remove jfreeman from TODO * Remove unneeded parenthesis 2017-07-06 23:45:50 +02:00			`function doThing() {`
			`__call: while (true) {`
			`aLabel: for (let i = 0; i < 10; i++) {`
			`if (i === 3) {`
			`break __call;`
			`}`
			`if (i === 5) {`
			`break aLabel;`
			`}`
			`}`
			`}`
			`}`
			`doThing();`