From 33a227503adfaa570174c48d8c893f968ed8337f Mon Sep 17 00:00:00 2001
From: Alexander Sosedkin <monk@unboiled.info>
Date: Sat, 27 Nov 2021 23:02:04 +0100
Subject: [PATCH] Document libsodium, which is now mandatory, as a dependency

---
 configure.ac                                        | 2 +-
 doc/manual/src/installation/prerequisites-source.md | 5 +++++
 perl/configure.ac                                   | 2 +-
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index 65478ecc5..bca650005 100644
--- a/configure.ac
+++ b/configure.ac
@@ -188,7 +188,7 @@ PKG_CHECK_MODULES([EDITLINE], [libeditline], [CXXFLAGS="$EDITLINE_CFLAGS $CXXFLA
     [AC_MSG_ERROR([Nix requires libeditline; it was not found via pkg-config, but via its header, but required functions do not work. Maybe it is too old? >= 1.14 is required.])])
 ])
 
-# Look for libsodium, an optional dependency.
+# Look for libsodium.
 PKG_CHECK_MODULES([SODIUM], [libsodium], [CXXFLAGS="$SODIUM_CFLAGS $CXXFLAGS"])
 
 # Look for libbrotli{enc,dec}.
diff --git a/doc/manual/src/installation/prerequisites-source.md b/doc/manual/src/installation/prerequisites-source.md
index 0323a4f55..b3753b53b 100644
--- a/doc/manual/src/installation/prerequisites-source.md
+++ b/doc/manual/src/installation/prerequisites-source.md
@@ -44,6 +44,11 @@
     obtained from the its repository
     <https://github.com/troglobit/editline>.
 
+  - The `libsodium` library for verifying cryptographic signatures
+    of contents fetched from binary caches.
+    It can be obtained from the official web site
+    <https://libsodium.org>.
+
   - Recent versions of Bison and Flex to build the parser. (This is
     because Nix needs GLR support in Bison and reentrancy support in
     Flex.) For Bison, you need version 2.6, which can be obtained from
diff --git a/perl/configure.ac b/perl/configure.ac
index eb65ac17b..a02cb06c9 100644
--- a/perl/configure.ac
+++ b/perl/configure.ac
@@ -41,7 +41,7 @@ perlarchname=$($perl -e 'use Config; print $Config{archname};')
 AC_SUBST(perllibdir, [${libdir}/perl5/site_perl/$perlversion/$perlarchname])
 AC_MSG_RESULT($perllibdir)
 
-# Look for libsodium, an optional dependency.
+# Look for libsodium.
 PKG_CHECK_MODULES([SODIUM], [libsodium], [CXXFLAGS="$SODIUM_CFLAGS $CXXFLAGS"])
 
 # Check for the required Perl dependencies (DBI and DBD::SQLite).