bug#60528: uri->string swallows mandatory slashes

[<tomas@tuxteam.de>]

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On Tue, Jan 03, 2023 at 09:00:48PM +0100, Liliana Marie Prikler wrote:
> Hi folks,
> 
> Below some unexpected behaviour observed in Guile 3.0.8, but it also
> dates back to 2.2.7 and possibly earlier versions.
> 
> scheme@(guile-user)> ,use (web uri)
> scheme@(guile-user)> (string->uri "file:///home") 
> $1 = #<<uri> scheme: file userinfo: #f host: #f port: #f path: "/home"
> query: #f fragment: #f>
> scheme@(guile-user)> (uri->string $1)
> $2 = "file:/home"

This looks strange, but not necessarily wrong. "file:///home" means
"empty authority", equivalent to "localhost" whereas "file:/home" means
"no authority". I'd expect the library to keep those two separate.
 
> scheme@(guile-user)> (uri->string (build-uri 'file #:host "" #:path
> "/home")) 
> ice-9/boot-9.scm:1685:16: In procedure raise-exception:
> Throw to key `uri-error' with args `("Expected valid host: ~s" (""))'.

Note that "no host" is not the empty string, but #f:

> scheme@(guile-user)> (uri->string (build-uri 'file #:host "" #:path
> "/home")) 

  scheme@(guile-user)> (uri->string (build-uri 'file #:host #f #:path "/home"))
  $6 = "file:/home"

So it is consistent, albeit (to me) surprising. I'd have expect
your `$2' above to be "file:///home", with three slashes.

Cheers
-- 
t

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