Accept Input Source Maps

The typescript compiler produces sources maps mapping from the javascript it produces to the typescript sources it compiled. This is great, but doesn't go far enough if there are tools which generate the sources that are consumed by the typescript compiler.

For example, Tsickle preprocesses typescript sources before passing them to the typescript compiler. As things stand we've had to implement a hack to get our source maps to work. We use a compiler host which performs the tsickle transforms as the typescript compiler reads files, saves the resulting source maps and then compose them with the source maps produced by the typescript compiler as they're emitted.

Instead the typescript compiler could accept source maps as input alongside sources, and compose the input source maps with the source maps produced by the compiler.

The ideal api would be that the typescript compiler would look for either a. an inline source map as a comment in the source file or b. a file in the same directory with the name {source file name}.ts.map, which shouldn't require any crazy file resolution.

L’issue ne nomme aucun fichier ni test du dépôt. Commencez par suivre le chemin d’émission des source maps du compiler host et la manière dont les sources transformées sont lues, puis déterminez où les maps inline ou les fichiers .ts.map adjacents seraient découverts et composés. Le travail est terminé lorsque le compilateur accepte les deux formes de maps d’entrée et les combine avec ses source maps émises.