transpilation doesn't handle multiple prologue directives

[ajafff]

TypeScript Version: 3.0.0-dev.20180605

Search Terms:

Code

// this is obviously a bogus function just to have a minimal repro
function test(p: any) {
    'use strong';
    'use strict';
    p = {prop: p} = p;
}

Expected behavior:

function test(p) {
    'use strong';
    'use strict';
    var _a;
    p = (_a = p, p = _a.prop, _a);
}

Actual behavior:

function test(p) {
    'use strong';
    var _a;
    'use strict';
    p = (_a = p, p = _a.prop, _a);
}

The transpiled code has different semantics, because 'use strict' is no longer treated as directive.

I don't know if this also affects other transformers that add statements.

Note that TypeScript correctly detects the 'use strict' directive and would correctly complain about octal literals.

Playground Link:

Related Issues:
#24582
#24386 (comment)

[mhegazy]

A PR would be appreciated.