Specifying --outDir on the CLI causes error TS5055 with declarations

[slikts]

TypeScript Version: 2.4.0-dev.20170517, 2.3.2

Files to reproduce: https://gist.github.com/slikts/7a35d205e01b54f169c7d13dfe248a69 (just an empty .ts file and an empty tsconfig.json file)

$ tsc --outDir dist --declaration true
$ tsc --outDir dist --declaration true
error TS5055: Cannot write file 'dist/Foo.d.ts' because it would overwrite input file.

This error does not occur if the outDir option is set in tsconfig.json.

[mhegazy]

:D this is a fun one. so here is what is going on, if no exclude (or include) is specified explicitly in the tsconfig, one is created. by default, that is ["node_modules" , "<otutDir>"], but since the outDir is specified on the commend line, it is not taken into account when the tsconfig.json is parsed.

the result is a including the .d.ts that was generated the previous time, and hence the error, that hte output of foo.ts would overwrite an input dist/foo.d.ts.

A workaround would be to add include, or exclude with dist in your tsconfig.json, or just set the outDir in the tsconfig.json as you noted.