bug#75065: Upon archive download failure print the original error

[Konstantin Kharlamov <Hi-Angel@yandex.ru>]

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On Thu, 2024-12-26 at 23:53 +0300, Konstantin Kharlamov wrote:
> Oh, actually, let me fix the other place as well then…
> 
> On Thu, 2024-12-26 at 23:51 +0300, Konstantin Kharlamov wrote:
> > On Thu, 2024-12-26 at 15:40 -0500, Stefan Monnier wrote:
> > > > The `car` seems to just contain word error. Here's how both
> > > > compare:
> > > > 
> > > > • current patch with `(cdr err)`:
> > > >     Failed to download ‘melpa’ archive. Error: ("Location
> > > > melpa.org/packages/ is not a url nor an absolute file name")
> > > > 
> > > > • suggested change with `err`:
> > > >     Failed to download ‘melpa’ archive. Error: (error "Location
> > > > melpa.org/packages/ is not a url nor an absolute file name")
> > > > 
> > > > I can of course remove the word `Error` in the second case.
> > > > My question then is: will `(car err)` always be the word
> > > > "error"?
> > > > Or
> > > > may there be another content?
> > > 
> > > The shape and content of `err` depends on the actual error that
> > > caused
> > > the download to fail.  `(car err)` contains the error "type",
> > > which
> > > can
> > > be `error` but can also be more specific such as
> > > `wrong-number-of-arguments`, `file-error`, ...
> > 
> > Thank you, I see!
> > 
> > Please check the attached patch. With this change the error of
> > accessing https-less address is shown as follows:
> > 
> > 	Failed to download ‘melpa’ archive: (error "Location
> > melpa.org/packages/ is not a url nor an absolute file name")
> 

Done, please review 😊

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From 642c934fb0cb1650ffd5b13127774d73c8a1af35 Mon Sep 17 00:00:00 2001
From: Konstantin Kharlamov <Hi-Angel@yandex.ru>
Date: Tue, 24 Dec 2024 18:16:41 +0300
Subject: [PATCH 1/2] Upon archive download failure print the original error
 (Bug#75065)

* lisp/emacs-lisp/package.el (package--download-and-read-archives):
upon catching exception, use the exception message as part of the
error to provide more context about the failure.
---
 lisp/emacs-lisp/package.el | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lisp/emacs-lisp/package.el b/lisp/emacs-lisp/package.el
index 5f785071ea3..81f0ac0162f 100644
--- a/lisp/emacs-lisp/package.el
+++ b/lisp/emacs-lisp/package.el
@@ -1829,10 +1829,10 @@ Populate `package-archive-contents' with the result.
 If optional argument ASYNC is non-nil, perform the downloads
 asynchronously."
   (dolist (archive package-archives)
-    (condition-case-unless-debug nil
+    (condition-case-unless-debug err
         (package--download-one-archive archive "archive-contents" async)
-      (error (message "Failed to download `%s' archive."
-               (car archive))))))
+      (error (message "Failed to download `%s' archive: %S"
+               (car archive) err)))))
 
 (defvar package-refresh-contents-hook (list #'package--download-and-read-archives)
   "List of functions to call to refresh the package archive.
-- 
2.47.1


From cf8f2ca0915743027160dc516eea4fd565b62ffa Mon Sep 17 00:00:00 2001
From: Konstantin Kharlamov <Hi-Angel@yandex.ru>
Date: Thu, 26 Dec 2024 23:54:25 +0300
Subject: [PATCH 2/2] Upon keyring import fail print the full error (Bug#75065)

As discussed at Bug#75065, the `(car error)' contains the exception
type and it's better to print the full error content.

* lisp/emacs-lisp/package.el (package-refresh-contents): upon keyring
import failure print the full content.
---
 lisp/emacs-lisp/package.el | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lisp/emacs-lisp/package.el b/lisp/emacs-lisp/package.el
index 81f0ac0162f..e24db4567e1 100644
--- a/lisp/emacs-lisp/package.el
+++ b/lisp/emacs-lisp/package.el
@@ -1856,7 +1856,7 @@ downloads in the background."
     (when (and (package-check-signature) (file-exists-p default-keyring))
       (condition-case-unless-debug error
           (package-import-keyring default-keyring)
-        (error (message "Cannot import default keyring: %S" (cdr error))))))
+        (error (message "Cannot import default keyring: %S" error)))))
   (run-hook-with-args 'package-refresh-contents-hook async))
 
 \f
-- 
2.47.1