bug#10474: Building guile 2.x under mingw + msys

[Andy Wingo <wingo@pobox.com>]

Hi,

On Tue 19 Feb 2013 18:53, Eli Zaretskii <eliz@gnu.org> writes:

>> +       (define (unc-path?)
>> +         ;; Universal Naming Convention (UNC) paths start with \\, and
>> +         ;; are always absolute.
>> +         (string-prefix? "\\\\" path))
>
> A UNC file name can also begin with 2 slashes, as in "//foo/bar/".  In
> general, Windows system calls treat both kinds of slashes identically.

Interesting, thanks.

>>    (define (canonical->suffix canon)
>>      (cond
>> -     ((string-prefix? "/" canon) canon)
>> -     ((and (> (string-length canon) 2)
>> -           (eqv? (string-ref canon 1) #\:))
>> -      ;; Paths like C:... transform to /C...
>> -      (string-append "/" (substring canon 0 1) (substring canon 2)))
>> +     ((and (not (string-null? canon))
>> +           (path-separator? (string-ref canon 0)))
>> +      canon)
>> +     ((and (eq? (system-path-convention) 'windows)
>> +           (absolute-path? canon))
>> +      ;; An absolute path that doesn't start with a path separator starts with a
>> +      ;; drive component.  Transform the drive component to a path element:
>> +      ;; c:\foo -> \c\foo.
>
> Why is this transformation needed?  Native Windows system calls will
> not understand "/c/foo" syntax.  What is this about?  (I know it was
> in the original code, but I didn't understand it then, either.)

Auto-compiling /foo/bar/baz.scm produces
$HOME/.cache/guile/2.0/ccache/foo/bar/baz.go.  This turns the drive
component into a path element on Windows so compiling C:/foo.scm caches
$HOME/.cache/guile/2.0/ccache/c/foo.go.

Andy
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