Bug in -J

[Mr. Pib via Digitalmars-d]

On Saturday, 12 August 2017 at 06:06:33 UTC, Vladimir Panteleev 
wrote:
> On Saturday, 12 August 2017 at 06:02:57 UTC, Vladimir Panteleev 
> wrote:
>> Sounds reasonable, the compiler could check if paths start 
>> with a -J path.
>
> There is a potential ambiguity here:
>
> dmd -Jsomedir test.d
>
> test.d: import("somedir/file.txt");
>
> Does the user mean to import "somedir/file.txt" or 
> "somedir/somedir/file.txt"? Currently the latter is understood. 
> Simply checking for path prefix would break this case. I guess 
> this could be done only with absolute paths, but that 
> introduces an inconsistency with relative paths. I'm not sure 
> it's worth it, considering it's easy to work around.

What is the inconsistency? Absolute paths are specific and well 
defined and so are relatives. Relatives are always relative to J, 
are they not?

so, import("somedir/file.txt"); obviously means 
somedir/somedir/file.txt.

If you wanted somedir/file.txt you would do import(`file.txt`).

I see no problem here. With absolute paths, one simply checks if 
the absolute base path matches the absolute base path specified 
by J. If it matches, then it passes and can be used directly or 
removed internally. If not then an error is given.

e.g.,

-JC:/basepath/somedir
C:/basepath/somedir/file.txt

import('C:/basepath/somedir/file.txt')
import('file.txt')
import('../somedir/file.txt')
import('C:/basepath/../basepath/somedir/file.txt')
import('C:/path/../basepath/file.txt')

should pass all pass.

import('../file.txt')
import('C:/basepath/../basepath/file.txt')
import('C:/path/file.txt')

should all fail.

(I'm only using .. for reference, not sure if they should 
actually be supported)

It seems quite simple to me

Any relative paths specified by import are prepended with the 
path specified by -J. Any absolute paths specified by an import 
are first matched to the path -J simply by

example:

if (J_path.length < basepath.length) assert("Import path must be 
located in the same path that is specified by -J");

if (basepath[0..J_path.length] != J_path) ditto; // makes sure 
absolute path is in the -J path. This is the check that is 
missing from dmd.

(this doesn't resolve ..'s, that could be done before and assumes 
basepath is an absolute path)