packages: Introduce <content-hash> and use it in <origin>.

* guix/packages.scm (<content-hash>): New record type.
(define-content-hash-constructor, build-content-hash)
(content-hash): New macros.
(print-content-hash): New procedure.
(<origin>): Rename constructor to '%origin'.
[sha256]: Remove field.
[hash]: New field.  Adjust users.
(origin-compatibility-helper, origin): New macros.
(origin-sha256): New deprecated procedure.
(origin->derivation): Adjust accordingly.
* tests/packages.scm ("package-source-derivation, origin, sha512"): New
test.
* guix/tests.scm: Hide (gcrypt hash) 'sha256' for proper syntax
matching.
* tests/challenge.scm: Add #:prefix for (gcrypt hash) and adjust users.
* tests/derivations.scm: Likewise.
* tests/store.scm: Likewise.
* tests/graph.scm ("bag DAG, including origins"): Provide 'sha256' field
with the right length.
* gnu/packages/aspell.scm (aspell-dictionary)
(aspell-dict-ca, aspell-dict-it): Use 'hash' and 'content-hash' for
proper syntax matching.
* gnu/packages/bash.scm (bash-patch): Rename 'sha256' to 'sha256-bv'.
* gnu/packages/bootstrap.scm (bootstrap-executable): Rename 'sha256' to 'bv'.
* gnu/packages/readline.scm (readline-patch): Likewise.
* gnu/packages/virtualization.scm (qemu-patch): Rename 'sha256' to
'sha256-bv'.
* guix/import/utils.scm: Hide (gcrypt hash) 'sha256'.

1 files changed, 31 insertions, 3 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 01dab5b72c..c1e23b5ef3 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -5966,9 +5966,13 @@ specified in the @code{uri} field as a @code{git-reference} object; a
 @end table
 
 @item @code{sha256}
-A bytevector containing the SHA-256 hash of the source.  Typically the
-@code{base32} form is used here to generate the bytevector from a
-base-32 string.
+A bytevector containing the SHA-256 hash of the source.  This is
+equivalent to providing a @code{content-hash} SHA256 object in the
+@code{hash} field described below.
+
+@item @code{hash}
+The @code{content-hash} object of the source---see below for how to use
+@code{content-hash}.
 
 You can obtain this information using @code{guix download}
 (@pxref{Invoking guix download}) or @code{guix hash} (@pxref{Invoking
@@ -6013,6 +6017,30 @@ this is @code{#f}, a sensible default is used.
 @end table
 @end deftp
 
+@deftp {Data Type} content-hash @var{value} [@var{algorithm}]
+Construct a content hash object for the given @var{algorithm}, and with
+@var{value} as its hash value.  When @var{algorithm} is omitted, assume
+it is @code{sha256}.
+
+@var{value} can be a literal string, in which case it is base32-decoded,
+or it can be a bytevector.
+
+The following forms are all equivalent:
+
+@lisp
+(content-hash "05zxkyz9bv3j9h0xyid1rhvh3klhsmrpkf3bcs6frvlgyr2gwilj")
+(content-hash "05zxkyz9bv3j9h0xyid1rhvh3klhsmrpkf3bcs6frvlgyr2gwilj"
+              sha256)
+(content-hash (base32
+               "05zxkyz9bv3j9h0xyid1rhvh3klhsmrpkf3bcs6frvlgyr2gwilj"))
+(content-hash (base64 "kkb+RPaP7uyMZmu4eXPVkM4BN8yhRd8BTHLslb6f/Rc=")
+              sha256)
+@end lisp
+
+Technically, @code{content-hash} is currently implemented as a macro.
+It performs sanity checks at macro-expansion time, when possible, such
+as ensuring that @var{value} has the right size for @var{algorithm}.
+@end deftp
 
 @node Build Systems
 @section Build Systems