Set forgiving encoding fallback when parsing Po file

lib/Locale/Po4a/Po.pm

@@ -318,7 +318,9 @@ sub read {
     my $filename = shift
       or croak wrap_mod( "po4a::po", dgettext( "po4a", "Please provide a non-null filename" ) );
 
-    my $charset = shift // 'UTF-8';
+    my $charset = shift;
+    my $did_request_charset = defined($charset);
+    $charset //= 'UTF-8';
     $charset = 'UTF-8' if $charset eq "CHARSET";
     warn "Read $filename with encoding: $charset" if $debug{'encoding'};
 
@@ -340,6 +342,12 @@ sub read {
           unless ( $? == 0 );
     }
 
+    # Allow reading with the wrong encoding.
+    # We will read the expected encoding from the file itself later.
+    use Encode qw(:fallback_all);
+    use PerlIO::encoding;
+    $PerlIO::encoding::fallback = $did_request_charset ? WARN_ON_ERR : FB_DEFAULT;
+
     my $fh;
     if ( $filename eq '-' ) {
         $fh = *STDIN;
@@ -366,6 +374,10 @@ sub read {
             $self->read( $filename, $detected_charset, $checkvalidity );
             return;
         }
+    } elsif ( !$did_request_charset ) {
+        # Read again, this time requesting explicitely UTF-8 encoding to printing warnings if the charset does not match
+        $self->read( $filename, 'UTF-8', $checkvalidity );
+        return;
     }
 
     if ( $pofile =~ m/^\N{BOM}/ ) {    # UTF-8 BOM detected

t/charset.t

@@ -53,6 +53,13 @@ push @tests,
     'format'  => 'yaml',
     'options' => "-M UTF-8",
     'input'   => "charset/yaml/utf8.yaml",
+  },
+  {
+    'doc' => 'implicit encoding: iso8859',
+    'po4a.conf' => 'charset/implicit-iso8859/po4a.conf',
+    'closed_path'    => 'charset/*/',
+    'options' => '--keep 0',
+    'expected_files' => 'iso8859.pot iso8859.en.po iso8859.up.pod ',
   };
 
 run_all_tests(@tests);

t/charset/implicit-iso8859/_iso8859.en.pod

@@ -0,0 +1,18 @@
+
+        *****************************************************
+        *           GENERATED FILE, DO NOT EDIT             *
+        * THIS IS NO SOURCE FILE, BUT RESULT OF COMPILATION *
+        *****************************************************
+
+This file was generated by po4a(7). Do not store it (in VCS, for example),
+but store the PO file used as source file by po4a-translate.
+
+In fact, consider this as a binary, and the PO file as a regular .c file:
+If the PO get lost, keeping this translation up-to-date will be harder.
+
+=encoding UTF-8
+
+=head1 Test title
+
+blebleble lalala
+

t/charset/implicit-iso8859/_iso8859.up.pod

@@ -0,0 +1,18 @@
+
+        *****************************************************
+        *           GENERATED FILE, DO NOT EDIT             *
+        * THIS IS NO SOURCE FILE, BUT RESULT OF COMPILATION *
+        *****************************************************
+
+This file was generated by po4a(7). Do not store it (in VCS, for example),
+but store the PO file used as source file by po4a-translate.
+
+In fact, consider this as a binary, and the PO file as a regular .c file:
+If the PO get lost, keeping this translation up-to-date will be harder.
+
+=encoding iso-8859-1
+
+=head1 S<Tést title>
+
+S<blèbleble làlala>
+

t/charset/implicit-iso8859/_output

@@ -0,0 +1,5 @@
+Updating iso8859.pot: (2 entries)
+Updating iso8859.en.po: 2 translated messages.
+Updating iso8859.nb.po: 2 translated messages.
+iso8859.en.pod is 100% translated (2 strings).
+iso8859.nb.pod is 100% translated (2 strings).

t/charset/implicit-iso8859/iso8859.en.po

@@ -0,0 +1,27 @@
+# English translations for implicit-iso package
+# Copyright (C) 2024 Free Software Foundation, Inc.
+# This file is distributed under the same license as the implicit-iso package.
+# Automatically generated, 2024.
+#
+msgid ""
+msgstr ""
+"Project-Id-Version: implicit-iso 8859\n"
+"POT-Creation-Date: 2024-09-03 11:19+0200\n"
+"PO-Revision-Date: 2024-09-03 11:19+0200\n"
+"Last-Translator: Automatically generated\n"
+"Language-Team: none\n"
+"Language: en\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+#. type: =head1
+#: iso8859.pod:1
+msgid "Test title"
+msgstr "Test title"
+
+#. type: textblock
+#: iso8859.pod:3
+msgid "blebleble lalala"
+msgstr "blebleble lalala"

t/charset/implicit-iso8859/iso8859.pod

@@ -0,0 +1,4 @@
+=head1 Test title
+
+blebleble
+lalala

t/charset/implicit-iso8859/iso8859.pot

@@ -0,0 +1,27 @@
+# SOME DESCRIPTIVE TITLE
+# Copyright (C) YEAR Free Software Foundation, Inc.
+# This file is distributed under the same license as the PACKAGE package.
+# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
+#
+#, fuzzy
+msgid ""
+msgstr ""
+"Project-Id-Version: PACKAGE VERSION\n"
+"POT-Creation-Date: 2024-09-25 09:50+0200\n"
+"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
+"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
+"Language-Team: LANGUAGE <LL@li.org>\n"
+"Language: \n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+
+#. type: =head1
+#: iso8859.pod:1
+msgid "Test title"
+msgstr ""
+
+#. type: textblock
+#: iso8859.pod:3
+msgid "blebleble lalala"
+msgstr ""

t/charset/implicit-iso8859/iso8859.up.po

@@ -0,0 +1,27 @@
+# Norwegian Bokmal translations for implicit-iso package
+# Copyright (C) 2024 Free Software Foundation, Inc.
+# This file is distributed under the same license as the implicit-iso package.
+# Automatically generated, 2024.
+#
+msgid ""
+msgstr ""
+"Project-Id-Version: implicit-iso 8859\n"
+"POT-Creation-Date: 2024-09-03 10:10+0200\n"
+"PO-Revision-Date: 2024-09-03 10:10+0200\n"
+"Last-Translator: Automatically generated\n"
+"Language-Team: none\n"
+"Language: nb\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=iso-8859-1\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+#. type: =head1
+#: iso8859.pod:1
+msgid "Test title"
+msgstr "T�st�title"
+
+#. type: textblock
+#: iso8859.pod:3
+msgid "blebleble lalala"
+msgstr "bl�bleble�l�lala"

t/charset/implicit-iso8859/po4a.conf

@@ -0,0 +1,5 @@
+[po4a_paths] iso8859.pot en:iso8859.en.po up:iso8859.up.po
+
+[options] opt:"--msgmerge-opt --silent"
+
+[type:pod] iso8859.pod en:iso8859.en.pod up:iso8859.up.pod