l3 (28aug21)

git-svn-id: svn://tug.org/texlive/trunk@60338 c570f23f-e606-0410-a88d-b1316a301751

1 files changed, 180 insertions, 378 deletions

diff --git a/Master/texmf-dist/source/latex/l3kernel/l3msg.dtx b/Master/texmf-dist/source/latex/l3kernel/l3msg.dtx
index d08550273e9..0c689251a4d 100644
--- a/Master/texmf-dist/source/latex/l3kernel/l3msg.dtx
+++ b/Master/texmf-dist/source/latex/l3kernel/l3msg.dtx
@@ -43,7 +43,7 @@
 %    }^^A
 % }
 %
-% \date{Released 2021-07-12}
+% \date{Released 2021-08-27}
 %
 % \maketitle
 %
@@ -693,7 +693,7 @@
   {
     \msg_if_exist:nnT {#1} {#2}
       {
-        \__kernel_msg_error:nnxx { msg } { already-defined }
+        \msg_error:nnxx { msg } { already-defined }
           {#1} {#2}
       }
   }
@@ -1166,8 +1166,12 @@
 %   }
 %   For an error, the interrupt routine is called.  We check if there is
 %   a \enquote{more text} by comparing that control sequence with a
-%   permanently empty text.
+%   permanently empty text. We have to undefine the bootstrap versions
+%   here.
 %    \begin{macrocode}
+  \cs_undefine:N \msg_error:nnxx
+  \cs_undefine:N \msg_error:nnx
+  \cs_undefine:N \msg_error:nn
   \@@_class_new:nn { error }
     {
       \@@_interrupt:NnnnN
@@ -1180,6 +1184,7 @@
 %
 % \begin{macro}
 %   {
+%     \@@_info_aux:NNnnnnnn ,
 %     \msg_warning:nnnnnn ,
 %     \msg_warning:nnnnn  ,
 %     \msg_warning:nnnn   ,
@@ -1188,38 +1193,7 @@
 %     \msg_warning:nnxxxx ,
 %     \msg_warning:nnxxx  ,
 %     \msg_warning:nnxx   ,
-%     \msg_warning:nnx
-%   }
-%   Warnings are printed to the terminal.
-%    \begin{macrocode}
-  \@@_class_new:nn { warning }
-    {
-      \str_set:Nx \l_@@_text_str { \msg_warning_text:n {#1} }
-      \str_set:Nx \l_@@_name_str { \msg_module_name:n {#1} }
-      \iow_term:n { }
-      \iow_wrap:nxnN
-        {
-          \l_@@_text_str : ~
-          \use:c { \c_@@_text_prefix_tl #1 / #2 } {#3} {#4} {#5} {#6}
-        }
-        {
-          ( \l_@@_name_str )
-          \prg_replicate:nn
-            {
-                \str_count:N \l_@@_text_str
-              - \str_count:N \l_@@_name_str
-            }
-            { ~ }
-        }
-        { } \iow_term:n
-      \iow_term:n { }
-    }
-%    \end{macrocode}
-% \end{macro}
-%
-% \begin{macro}
-%   {
-%     \@@_info_aux:Nnn      ,
+%     \msg_warning:nnx    ,
 %     \msg_note:nnnnnn ,
 %     \msg_note:nnnnn  ,
 %     \msg_note:nnnn   ,
@@ -1237,27 +1211,22 @@
 %     \msg_info:nnxxxx ,
 %     \msg_info:nnxxx  ,
 %     \msg_info:nnxx   ,
-%     \msg_info:nnx
+%     \msg_info:nnx    ,
 %   }
-%   Information has no decoration and goes either to the log or both
-%   log and terminal.
+%   Warnings and information messages have no decoration.  Warnings are
+%   printed to the terminal while information can either go to the log
+%   or both log and terminal.
 %    \begin{macrocode}
-  \@@_class_new:nn { note }
-    {
-      \@@_info_aux:Nnn \iow_term:n {#1}
-        { \use:c { \c_@@_text_prefix_tl #1 / #2 } {#3} {#4} {#5} {#6} }
-    }
-  \@@_class_new:nn { info }
+  \cs_new_protected:Npn \@@_info_aux:NNnnnnnn #1#2#3#4#5#6#7#8
     {
-      \@@_info_aux:Nnn \iow_log:n {#1}
-        { \use:c { \c_@@_text_prefix_tl #1 / #2 } {#3} {#4} {#5} {#6} }
-    }
-  \cs_new_protected:Npn \@@_info_aux:Nnn #1#2#3
-    {
-      \str_set:Nx \l_@@_text_str { \msg_info_text:n {#2} }
-      \str_set:Nx \l_@@_name_str { \msg_module_name:n {#2} }
+      \str_set:Nx \l_@@_text_str { #2 {#3} }
+      \str_set:Nx \l_@@_name_str { \msg_module_name:n {#3} }
       #1 { }
-      \iow_wrap:nxnN { \l_@@_text_str : ~ #3 }
+      \iow_wrap:nxnN
+        {
+          \l_@@_text_str : ~
+          \use:c { \c_@@_text_prefix_tl #3 / #4 } {#5} {#6} {#7} {#8}
+        }
         {
           ( \l_@@_name_str )
           \prg_replicate:nn
@@ -1270,6 +1239,21 @@
          { } #1
        #1 { }
     }
+  \@@_class_new:nn { warning }
+    {
+      \@@_info_aux:NNnnnnnn \iow_term:n \msg_warning_text:n
+        {#1} {#2} {#3} {#4} {#5} {#6}
+    }
+  \@@_class_new:nn { note }
+    {
+      \@@_info_aux:NNnnnnnn \iow_term:n \msg_info_text:n
+        {#1} {#2} {#3} {#4} {#5} {#6}
+    }
+  \@@_class_new:nn { info }
+    {
+      \@@_info_aux:NNnnnnnn \iow_log:n \msg_info_text:n
+        {#1} {#2} {#3} {#4} {#5} {#6}
+    }
 %    \end{macrocode}
 % \end{macro}
 %
@@ -1283,22 +1267,7 @@
 %     \msg_log:nnxxxx ,
 %     \msg_log:nnxxx  ,
 %     \msg_log:nnxx   ,
-%     \msg_log:nnx
-%   }
-%   \enquote{Log} data is very similar to information, but with no extras
-%   added.
-%    \begin{macrocode}
-  \@@_class_new:nn { log }
-    {
-      \iow_wrap:nnnN
-        { \use:c { \c_@@_text_prefix_tl #1 / #2 } {#3} {#4} {#5} {#6} }
-        { } { } \iow_log:n
-    }
-%    \end{macrocode}
-% \end{macro}
-%
-% \begin{macro}
-%   {
+%     \msg_log:nnx    ,
 %     \msg_term:nnnnnn ,
 %     \msg_term:nnnnn  ,
 %     \msg_term:nnnn   ,
@@ -1307,12 +1276,20 @@
 %     \msg_term:nnxxxx ,
 %     \msg_term:nnxxx  ,
 %     \msg_term:nnxx   ,
-%     \msg_term:nnx
+%     \msg_term:nnx    ,
 %   }
+%   \enquote{Log} data is very similar to information, but with no extras
+%   added.
 %   \enquote{Term} is used for communicating with the user through the
 %   terminal, like diagnostic messages, and debugging.  This is similar
 %   to \enquote{log} messages, but uses the terminal output.
 %    \begin{macrocode}
+  \@@_class_new:nn { log }
+    {
+      \iow_wrap:nnnN
+        { \use:c { \c_@@_text_prefix_tl #1 / #2 } {#3} {#4} {#5} {#6} }
+        { } { } \iow_log:n
+    }
   \@@_class_new:nn { term }
     {
       \iow_wrap:nnnN
@@ -1415,7 +1392,7 @@
 \cs_new:Npn \@@_class_chk_exist:nT #1
   {
     \cs_if_free:cTF { @@_ #1 _code:nnnnnn }
-      { \__kernel_msg_error:nnx { msg } { class-unknown } {#1} }
+      { \msg_error:nnx { msg } { class-unknown } {#1} }
   }
 %    \end{macrocode}
 % \end{macro}
@@ -1485,7 +1462,7 @@
             \@@_use_redirect_name:n { #2 / #3 }
           }
       }
-      { \__kernel_msg_error:nnxx { msg } { unknown } {#2} {#3} }
+      { \msg_error:nnxx { msg } { unknown } {#2} {#3} }
     \cs_if_exist_use:N \conditionally@traceon
   }
 \cs_new_protected:Npn \@@_use_code: { }
@@ -1635,7 +1612,7 @@
             \tl_if_eq:NNTF \l_@@_class_tl \l_@@_current_class_tl
               {
                 \prop_put:cnn { l_@@_redirect_ #2 _prop } {#3} {#2}
-                \__kernel_msg_warning:nnxxxx
+                \msg_warning:nnxxxx
                   { msg } { redirect-loop }
                   { \seq_item:Nn \l_@@_class_loop_seq { 1 } }
                   { \seq_item:Nn \l_@@_class_loop_seq { 2 } }
@@ -1659,177 +1636,64 @@
 %
 % \subsection{Kernel-specific functions}
 %
-% \begin{macro}{\__kernel_msg_new:nnnn, \__kernel_msg_new:nnn}
-% \begin{macro}{\__kernel_msg_set:nnnn, \__kernel_msg_set:nnn}
-%   The kernel needs some messages of its own. These are created using
-%   pre-built functions. Two functions are provided: one more general
-%   and one which only has the short text part.
-%    \begin{macrocode}
-\cs_new_protected:Npn \__kernel_msg_new:nnnn #1#2
-  { \msg_new:nnnn { LaTeX } { #1 / #2 } }
-\cs_new_protected:Npn \__kernel_msg_new:nnn #1#2
-  { \msg_new:nnn { LaTeX } { #1 / #2 } }
-\cs_new_protected:Npn \__kernel_msg_set:nnnn #1#2
-  { \msg_set:nnnn { LaTeX } { #1 / #2 } }
-\cs_new_protected:Npn \__kernel_msg_set:nnn #1#2
-  { \msg_set:nnn { LaTeX } { #1 / #2 } }
-%    \end{macrocode}
-% \end{macro}
-% \end{macro}
+% These are all retained purely for older \pkg{xparse} support.
 %
-% \begin{macro}{\@@_kernel_class_new:nN}
-% \begin{macro}{\@@_kernel_class_new_aux:nN}
-%   All the functions for kernel messages come in variants ranging
-%   from~$0$ to~$4$ arguments.  Those with less than~$4$ arguments are
-%   defined in terms of the $4$-argument variant, in a way very similar
-%   to \cs{@@_class_new:nn}.  This auxiliary is destroyed at the end of
-%   the group.
-%    \begin{macrocode}
-\group_begin:
-  \cs_set_protected:Npn \@@_kernel_class_new:nN #1
-    { \@@_kernel_class_new_aux:nN { __kernel_msg_ #1 } }
-  \cs_set_protected:Npn \@@_kernel_class_new_aux:nN #1#2
-    {
-      \cs_new_protected:cpn { #1 :nnnnnn } ##1##2##3##4##5##6
-        {
-          \use:x
-            {
-              \exp_not:n { #2 { LaTeX } { ##1 / ##2 } }
-                { \tl_to_str:n {##3} } { \tl_to_str:n {##4} }
-                { \tl_to_str:n {##5} } { \tl_to_str:n {##6} }
-            }
-        }
-      \cs_new_protected:cpx { #1 :nnnnn } ##1##2##3##4##5
-        { \exp_not:c { #1 :nnnnnn } {##1} {##2} {##3} {##4} {##5} { } }
-      \cs_new_protected:cpx { #1 :nnnn } ##1##2##3##4
-        { \exp_not:c { #1 :nnnnnn } {##1} {##2} {##3} {##4} { } { } }
-      \cs_new_protected:cpx { #1 :nnn } ##1##2##3
-        { \exp_not:c { #1 :nnnnnn } {##1} {##2} {##3} { } { } { } }
-      \cs_new_protected:cpx { #1 :nn } ##1##2
-        { \exp_not:c { #1 :nnnnnn } {##1} {##2} { } { } { } { } }
-      \cs_new_protected:cpx { #1 :nnxxxx } ##1##2##3##4##5##6
-        {
-          \use:x
-            {
-              \exp_not:N \exp_not:n
-                { \exp_not:c { #1 :nnnnnn } {##1} {##2} }
-                {##3} {##4} {##5} {##6}
-            }
-        }
-      \cs_new_protected:cpx { #1 :nnxxx } ##1##2##3##4##5
-        { \exp_not:c { #1 :nnxxxx } {##1} {##2} {##3} {##4} {##5} { } }
-      \cs_new_protected:cpx { #1 :nnxx } ##1##2##3##4
-        { \exp_not:c { #1 :nnxxxx } {##1} {##2} {##3} {##4} { } { } }
-      \cs_new_protected:cpx { #1 :nnx } ##1##2##3
-        { \exp_not:c { #1 :nnxxxx } {##1} {##2} {##3} { } { } { } }
-    }
-%    \end{macrocode}
-% \end{macro}
-% \end{macro}
-%
-% \begin{macro}
-%   {
-%     \__kernel_msg_fatal:nnnnnn    ,
-%     \__kernel_msg_fatal:nnnnn     ,
-%     \__kernel_msg_fatal:nnnn      ,
-%     \__kernel_msg_fatal:nnn       ,
-%     \__kernel_msg_fatal:nn        ,
-%     \__kernel_msg_fatal:nnxxxx    ,
-%     \__kernel_msg_fatal:nnxxx     ,
-%     \__kernel_msg_fatal:nnxx      ,
-%     \__kernel_msg_fatal:nnx       ,
-%     \__kernel_msg_critical:nnnnnn ,
-%     \__kernel_msg_critical:nnnnn  ,
-%     \__kernel_msg_critical:nnnn   ,
-%     \__kernel_msg_critical:nnn    ,
-%     \__kernel_msg_critical:nn     ,
-%     \__kernel_msg_critical:nnxxxx ,
-%     \__kernel_msg_critical:nnxxx  ,
-%     \__kernel_msg_critical:nnxx   ,
-%     \__kernel_msg_critical:nnx    ,
-%     \__kernel_msg_error:nnnnnn    ,
-%     \__kernel_msg_error:nnnnn     ,
-%     \__kernel_msg_error:nnnn      ,
-%     \__kernel_msg_error:nnn       ,
-%     \__kernel_msg_error:nn        ,
-%     \__kernel_msg_error:nnxxxx    ,
-%     \__kernel_msg_error:nnxxx     ,
-%     \__kernel_msg_error:nnxx      ,
-%     \__kernel_msg_error:nnx
-%   }
-%   Neither fatal kernel errors nor kernel errors can be redirected.  We
-%   directly use the code for (non-kernel) fatal errors and errors,
-%   adding the \enquote{\LaTeX{}} module name.  Three functions are
-%   already defined by \pkg{l3basics}; we need to undefine them to avoid
-%   errors.
+% \begin{macro}{\__kernel_msg_new:nnnn, \__kernel_msg_new:nnn}
 %    \begin{macrocode}
-  \@@_kernel_class_new:nN { fatal } \@@_fatal_code:nnnnnn
-  \@@_kernel_class_new:nN { critical } \@@_critical_code:nnnnnn
-  \cs_undefine:N \__kernel_msg_error:nnxx
-  \cs_undefine:N \__kernel_msg_error:nnx
-  \cs_undefine:N \__kernel_msg_error:nn
-  \@@_kernel_class_new:nN { error } \@@_error_code:nnnnnn
+\cs_new_protected:Npn \__kernel_msg_new:nnnn #1
+  { \msg_new:nnnn { LaTeX / #1 } }
+\cs_new_protected:Npn \__kernel_msg_new:nnn #1
+  { \msg_new:nnn { LaTeX / #1 } }
 %    \end{macrocode}
 % \end{macro}
 %
 % \begin{macro}
 %   {
-%     \__kernel_msg_warning:nnnnnn ,
-%     \__kernel_msg_warning:nnnnn  ,
-%     \__kernel_msg_warning:nnnn   ,
-%     \__kernel_msg_warning:nnn    ,
-%     \__kernel_msg_warning:nn     ,
-%     \__kernel_msg_warning:nnxxxx ,
-%     \__kernel_msg_warning:nnxxx  ,
-%     \__kernel_msg_warning:nnxx   ,
-%     \__kernel_msg_warning:nnx    ,
-%     \__kernel_msg_info:nnnnnn    ,
-%     \__kernel_msg_info:nnnnn     ,
-%     \__kernel_msg_info:nnnn      ,
-%     \__kernel_msg_info:nnn       ,
-%     \__kernel_msg_info:nn        ,
-%     \__kernel_msg_info:nnxxxx    ,
-%     \__kernel_msg_info:nnxxx     ,
-%     \__kernel_msg_info:nnxx      ,
-%     \__kernel_msg_info:nnx
+%     \__kernel_msg_info:nnxx    ,
+%     \__kernel_msg_warning:nnx  ,
+%     \__kernel_msg_warning:nnxx ,
+%     \__kernel_msg_error:nnx    ,
+%     \__kernel_msg_error:nnxx   ,
+%     \__kernel_msg_error:nnxxx
 %   }
-%   Kernel messages which can be redirected simply use the machinery for
-%   normal messages, with the module name \enquote{\LaTeX{}}.
 %    \begin{macrocode}
-  \@@_kernel_class_new:nN { warning } \msg_warning:nnxxxx
-  \@@_kernel_class_new:nN { info } \msg_info:nnxxxx
+\cs_new_protected:Npn \__kernel_msg_info:nnxx #1
+  { \msg_info:nnxx { LaTeX / #1 } }
+\cs_new_protected:Npn \__kernel_msg_warning:nnx #1
+  { \msg_warning:nnx { LaTeX / #1 } }
+\cs_new_protected:Npn \__kernel_msg_warning:nnxx #1
+  { \msg_warning:nnxx { LaTeX / #1 } }
+\cs_new_protected:Npn \__kernel_msg_error:nnx #1
+  { \msg_error:nnx { LaTeX / #1 } }
+\cs_new_protected:Npn \__kernel_msg_error:nnxx #1
+  { \msg_error:nnxx { LaTeX / #1 } }
+\cs_new_protected:Npn \__kernel_msg_error:nnxxx #1
+  { \msg_error:nnxxx { LaTeX / #1 } }
 %    \end{macrocode}
 % \end{macro}
 %
 % \begin{macro}
 %   {
-%     \__kernel_msg_log:nnnnnn, \__kernel_msg_log:nnxxxx,
-%     \__kernel_msg_term:nnnnnn, \__kernel_msg_term:nnxxxx,
-%     \__kernel_msg_show:nnnnnn, \__kernel_msg_show:nnxxxx
+%     \__kernel_msg_expandable_error:nnn ,
+%     \__kernel_msg_expandable_error:nnf ,
+%     \__kernel_msg_expandable_error:nnff
 %   }
-%   For showing messages.
 %    \begin{macrocode}
-\cs_new_protected:Npn \__kernel_msg_log:nnnnnn #1
-  { \msg_log:nnnnnn { LaTeX / #1 } }
-\cs_generate_variant:Nn \__kernel_msg_log:nnnnnn { nnxxxx }
-\cs_new_protected:Npn \__kernel_msg_term:nnnnnn #1
-  { \msg_term:nnnnnn { LaTeX / #1 } }
-\cs_generate_variant:Nn \__kernel_msg_term:nnnnnn { nnxxxx }
-\cs_new_protected:Npn \__kernel_msg_show:nnnnnn #1
-  { \msg_show:nnnnnn { LaTeX / #1 } }
-\cs_generate_variant:Nn \__kernel_msg_show:nnnnnn { nnxxxx }
+\cs_new:Npn \__kernel_msg_expandable_error:nnn #1
+  { \msg_expandable_error:nnn { LaTeX / #1 } }
+\cs_new:Npn \__kernel_msg_expandable_error:nnf #1
+  { \msg_expandable_error:nnf { LaTeX / #1 } }
+\cs_new:Npn \__kernel_msg_expandable_error:nnff #1
+  { \msg_expandable_error:nnff { LaTeX / #1 } }
 %    \end{macrocode}
 % \end{macro}
 %
-% End the group to eliminate \cs{@@_kernel_class_new:nN}.
-%    \begin{macrocode}
-\group_end:
-%    \end{macrocode}
+% \subsection{Internal messages}
 %
 % Error messages needed to actually implement the message system
 % itself.
 %    \begin{macrocode}
-\__kernel_msg_new:nnnn { msg } { already-defined }
+\msg_new:nnnn { msg } { already-defined }
   { Message~'#2'~for~module~'#1'~already~defined. }
   {
     \c_@@_coding_error_text_tl
@@ -1837,7 +1701,7 @@
     by~the~module~'#1':~this~message~already~exists.
     \c_@@_return_text_tl
   }
-\__kernel_msg_new:nnnn { msg } { unknown }
+\msg_new:nnnn { msg } { unknown }
   { Unknown~message~'#2'~for~module~'#1'. }
   {
     \c_@@_coding_error_text_tl
@@ -1845,14 +1709,14 @@
     by~the~module~'#1':~this~message~does~not~exist.
     \c_@@_return_text_tl
   }
-\__kernel_msg_new:nnnn { msg } { class-unknown }
+\msg_new:nnnn { msg } { class-unknown }
   { Unknown~message~class~'#1'. }
   {
     LaTeX~has~been~asked~to~redirect~messages~to~a~class~'#1':\\
     this~was~never~defined.
     \c_@@_return_text_tl
   }
-\__kernel_msg_new:nnnn { msg } { redirect-loop }
+\msg_new:nnnn { msg } { redirect-loop }
   {
     Message~redirection~loop~caused~by~ {#1} ~=>~ {#2}
     \tl_if_empty:nF {#3} { ~for~module~' \use_none:n #3 ' } .
@@ -1868,7 +1732,7 @@
 % Messages for earlier kernel modules plus a few for \pkg{l3keys} which
 % cover coding errors.
 %    \begin{macrocode}
-\__kernel_msg_new:nnnn { kernel } { bad-number-of-arguments }
+\msg_new:nnnn { kernel } { bad-number-of-arguments }
   { Function~'#1'~cannot~be~defined~with~#2~arguments. }
   {
     \c_@@_coding_error_text_tl
@@ -1876,7 +1740,7 @@
     #2~arguments.~
     TeX~allows~between~0~and~9~arguments~for~a~single~function.
   }
-\__kernel_msg_new:nnnn { kernel } { command-already-defined }
+\msg_new:nnnn { kernel } { command-already-defined }
   { Control~sequence~#1~already~defined. }
   {
     \c_@@_coding_error_text_tl
@@ -1885,28 +1749,21 @@
     The~current~meaning~is:\\
     \ \ #2
   }
-\__kernel_msg_new:nnnn { kernel } { command-not-defined }
+\msg_new:nnnn { kernel } { command-not-defined }
   { Control~sequence~#1~undefined. }
   {
     \c_@@_coding_error_text_tl
     LaTeX~has~been~asked~to~use~a~control~sequence~'#1':\\
     this~has~not~been~defined~yet.
   }
-\__kernel_msg_new:nnnn { kernel } { empty-search-pattern }
+\msg_new:nnnn { kernel } { empty-search-pattern }
   { Empty~search~pattern. }
   {
     \c_@@_coding_error_text_tl
     LaTeX~has~been~asked~to~replace~an~empty~pattern~by~'#1':~that~
     would~lead~to~an~infinite~loop!
   }
-\__kernel_msg_new:nnnn { kernel } { out-of-registers }
-  { No~room~for~a~new~#1. }
-  {
-    TeX~only~supports~\int_use:N \c_max_register_int \ %
-    of~each~type.~All~the~#1~registers~have~been~used.~
-    This~run~will~be~aborted~now.
-  }
-\__kernel_msg_new:nnnn { kernel } { non-base-function }
+\msg_new:nnnn { kernel } { non-base-function }
   { Function~'#1'~is~not~a~base~function }
   {
     \c_@@_coding_error_text_tl
@@ -1916,7 +1773,7 @@
     To~define~variants~use~\iow_char:N\\cs_generate_variant:Nn~
     and~to~define~other~functions~use~\iow_char:N\\cs_new:Npn.
   }
-\__kernel_msg_new:nnnn { kernel } { missing-colon }
+\msg_new:nnnn { kernel } { missing-colon }
   { Function~'#1'~contains~no~':'. }
   {
     \c_@@_coding_error_text_tl
@@ -1925,36 +1782,36 @@
     needed~when~defining~conditionals~or~variants,~or~when~building~a~
     parameter~text~from~the~number~of~arguments~of~the~function.
   }
-\__kernel_msg_new:nnnn { kernel } { overflow }
+\msg_new:nnnn { kernel } { overflow }
   { Integers~larger~than~2^{30}-1~cannot~be~stored~in~arrays. }
   {
     An~attempt~was~made~to~store~#3~
     \tl_if_empty:nF {#2} { at~position~#2~ } in~the~array~'#1'.~
     The~largest~allowed~value~#4~will~be~used~instead.
   }
-\__kernel_msg_new:nnnn { kernel } { out-of-bounds }
+\msg_new:nnnn { kernel } { out-of-bounds }
   { Access~to~an~entry~beyond~an~array's~bounds. }
   {
     An~attempt~was~made~to~access~or~store~data~at~position~#2~of~the~
     array~'#1',~but~this~array~has~entries~at~positions~from~1~to~#3.
   }
-\__kernel_msg_new:nnnn { kernel } { protected-predicate }
+\msg_new:nnnn { kernel } { protected-predicate }
   { Predicate~'#1'~must~be~expandable. }
   {
     \c_@@_coding_error_text_tl
     LaTeX~has~been~asked~to~define~'#1'~as~a~protected~predicate.~
     Only~expandable~tests~can~have~a~predicate~version.
   }
-\__kernel_msg_new:nnn { kernel } { randint-backward-range }
-  { Bounds~ordered~backwards~in~\iow_char:N\\int_rand:nn~{#1}~{#2}. }
-\__kernel_msg_new:nnnn { kernel } { conditional-form-unknown }
+\msg_new:nnn { kernel } { randint-backward-range }
+  { Wrong~order~of~bounds~in~\iow_char:N\\int_rand:nn{#1}{#2}. }
+\msg_new:nnnn { kernel } { conditional-form-unknown }
   { Conditional~form~'#1'~for~function~'#2'~unknown. }
   {
     \c_@@_coding_error_text_tl
     LaTeX~has~been~asked~to~define~the~conditional~form~'#1'~of~
     the~function~'#2',~but~only~'TF',~'T',~'F',~and~'p'~forms~exist.
   }
-\__kernel_msg_new:nnnn { kernel } { variant-too-long }
+\msg_new:nnnn { kernel } { variant-too-long }
   { Variant~form~'#1'~longer~than~base~signature~of~'#2'. }
   {
     \c_@@_coding_error_text_tl
@@ -1962,7 +1819,7 @@
     with~a~signature~starting~with~'#1',~but~that~is~longer~than~
     the~signature~(part~after~the~colon)~of~'#2'.
   }
-\__kernel_msg_new:nnnn { kernel } { invalid-variant }
+\msg_new:nnnn { kernel } { invalid-variant }
   { Variant~form~'#1'~invalid~for~base~form~'#2'. }
   {
     \c_@@_coding_error_text_tl
@@ -1970,7 +1827,7 @@
     with~a~signature~starting~with~'#1',~but~cannot~change~an~argument~
     from~type~'#3'~to~type~'#4'.
   }
-\__kernel_msg_new:nnnn { kernel } { invalid-exp-args }
+\msg_new:nnnn { kernel } { invalid-exp-args }
   { Invalid~variant~specifier~'#1'~in~'#2'. }
   {
     \c_@@_coding_error_text_tl
@@ -1978,7 +1835,7 @@
     function~with~signature~'N#2'~but~'#1'~is~not~a~valid~argument~
     specifier.
   }
-\__kernel_msg_new:nnn { kernel } { deprecated-variant }
+\msg_new:nnn { kernel } { deprecated-variant }
   {
     Variant~form~'#1'~deprecated~for~base~form~'#2'.~
     One~should~not~change~an~argument~from~type~'#3'~to~type~'#4'
@@ -1989,20 +1846,20 @@
         {#4} { :~base~form~is~already~a~variant. }
       } { . }
   }
-\__kernel_msg_new:nnn { char } { active }
+\msg_new:nnn { char } { active }
   { Cannot~generate~active~chars. }
-\__kernel_msg_new:nnn { char } { invalid-catcode }
+\msg_new:nnn { char } { invalid-catcode }
   { Invalid~catcode~for~char~generation. }
-\__kernel_msg_new:nnn { char } { null-space }
+\msg_new:nnn { char } { null-space }
   { Cannot~generate~null~char~as~a~space. }
-\__kernel_msg_new:nnn { char } { out-of-range }
+\msg_new:nnn { char } { out-of-range }
   { Charcode~requested~out~of~engine~range. }
-\__kernel_msg_new:nnn { char } { space }
+\msg_new:nnn { char } { space }
   { Cannot~generate~space~chars. }
-\__kernel_msg_new:nnnn { ior } { quote-in-shell }
+\msg_new:nnnn { ior } { quote-in-shell }
   { Quotes~in~shell~command~'#1'. }
   { Shell~commands~cannot~contain~quotes~("). }
-\__kernel_msg_new:nnnn { keys } { no-property }
+\msg_new:nnnn { keys } { no-property }
   { No~property~given~in~definition~of~key~'#1'. }
   {
     \c_@@_coding_error_text_tl
@@ -2011,27 +1868,27 @@
     \iow_indent:n { #1 .<property> } \\ \\
     LaTeX~did~not~find~a~'.'~to~indicate~the~start~of~a~property.
   }
-\__kernel_msg_new:nnnn { keys } { property-boolean-values-only }
+\msg_new:nnnn { keys } { property-boolean-values-only }
   { The~property~'#1'~accepts~boolean~values~only. }
   {
     \c_@@_coding_error_text_tl
     The~property~'#1'~only~accepts~the~values~'true'~and~'false'.
   }
-\__kernel_msg_new:nnnn { keys } { property-requires-value }
+\msg_new:nnnn { keys } { property-requires-value }
   { The~property~'#1'~requires~a~value. }
   {
     \c_@@_coding_error_text_tl
     LaTeX~was~asked~to~set~property~'#1'~for~key~'#2'.\\
     No~value~was~given~for~the~property,~and~one~is~required.
   }
-\__kernel_msg_new:nnnn { keys } { property-unknown }
+\msg_new:nnnn { keys } { property-unknown }
   { The~key~property~'#1'~is~unknown. }
   {
     \c_@@_coding_error_text_tl
     LaTeX~has~been~asked~to~set~the~property~'#1'~for~key~'#2':~
     this~property~is~not~defined.
   }
-\__kernel_msg_new:nnnn { quark } { invalid-function }
+\msg_new:nnnn { quark } { invalid-function }
   { Quark~test~function~'#1'~is~invalid. }
   {
     \c_@@_coding_error_text_tl
@@ -2043,14 +1900,14 @@
   }
 \__kernel_msg_new:nnn { quark } { invalid }
   { Invalid~quark~variable~'#1'. }
-\__kernel_msg_new:nnnn { scanmark } { already-defined }
+\msg_new:nnnn { scanmark } { already-defined }
   { Scan~mark~#1~already~defined. }
   {
     \c_@@_coding_error_text_tl
     LaTeX~has~been~asked~to~create~a~new~scan~mark~'#1'~
     but~this~name~has~already~been~used~for~a~scan~mark.
   }
-\__kernel_msg_new:nnnn { seq } { shuffle-too-large }
+\msg_new:nnnn { seq } { shuffle-too-large }
   { The~sequence~#1~is~too~long~to~be~shuffled~by~TeX. }
   {
     TeX~has~ \int_eval:n { \c_max_register_int + 1 } ~
@@ -2058,14 +1915,14 @@
     \int_use:N \c_max_register_int \ items.~
     The~list~will~not~be~shuffled.
   }
-\__kernel_msg_new:nnnn { kernel } { variable-not-defined }
+\msg_new:nnnn { kernel } { variable-not-defined }
   { Variable~#1~undefined. }
   {
     \c_@@_coding_error_text_tl
     LaTeX~has~been~asked~to~show~a~variable~#1,~but~this~has~not~
     been~defined~yet.
   }
-\__kernel_msg_new:nnnn { kernel } { bad-type }
+\msg_new:nnnn { kernel } { bad-type }
   { Variable~'#1'~is~not~a~valid~#3. }
   {
     \c_@@_coding_error_text_tl
@@ -2081,7 +1938,7 @@
           { internal~structure:\\\\\iow_indent:n {#4} }
       }
   }
-\__kernel_msg_new:nnnn { kernel } { non-clist }
+\msg_new:nnnn { clist } { non-clist }
   { Variable~'#1'~is~not~a~valid~clist. }
   {
     \c_@@_coding_error_text_tl
@@ -2097,7 +1954,7 @@
 % \texttt{log-functions}, or on the contrary if debugging is turned off.
 % In format mode the error is somewhat different.
 %    \begin{macrocode}
-\__kernel_msg_new:nnnn { debug } { enable-debug }
+\msg_new:nnnn { debug } { enable-debug }
   { To~use~'#1'~set~the~'enable-debug'~option. }
   {
     The~function~'#1'~will~be~ignored~because~it~can~only~work~if~
@@ -2111,55 +1968,55 @@
 % Some errors only appear in expandable settings,
 % hence don't need a \enquote{more-text} argument.
 %    \begin{macrocode}
-\__kernel_msg_new:nnn { kernel } { bad-exp-end-f }
+\msg_new:nnn { kernel } { bad-exp-end-f }
   { Misused~\exp_end_continue_f:w or~:nw }
-\__kernel_msg_new:nnn { kernel } { bad-variable }
+\msg_new:nnn { kernel } { bad-variable }
   { Erroneous~variable~#1 used! }
-\__kernel_msg_new:nnn { seq } { misused }
+\msg_new:nnn { seq } { misused }
   { A~sequence~was~misused. }
-\__kernel_msg_new:nnn { prop } { misused }
+\msg_new:nnn { prop } { misused }
   { A~property~list~was~misused. }
-\__kernel_msg_new:nnn { prg } { negative-replication }
+\msg_new:nnn { prg } { negative-replication }
   { Negative~argument~for~\iow_char:N\\prg_replicate:nn. }
-\__kernel_msg_new:nnn { prop } { prop-keyval }
+\msg_new:nnn { prop } { prop-keyval }
   { Missing/extra~'='~in~'#1'~(in~'..._keyval:Nn') }
-\__kernel_msg_new:nnn { kernel } { unknown-comparison }
-  { Relation~'#1'~unknown:~use~=,~<,~>,~==,~!=,~<=,~>=. }
-\__kernel_msg_new:nnn { kernel } { zero-step }
-  { Zero~step~size~for~step~function~#1. }
+\msg_new:nnn { kernel } { unknown-comparison }
+  { Relation~'#1'~not~among~=,<,>,==,!=,<=,>=. }
+\msg_new:nnn { kernel } { zero-step }
+  { Zero~step~size~for~function~#1. }
 \cs_if_exist:NF \tex_expanded:D
   {
-    \__kernel_msg_new:nnn { kernel } { e-type }
+    \msg_new:nnn { kernel } { e-type }
       { #1 ~ in~e-type~argument }
   }
 %    \end{macrocode}
 %
 % Messages used by the \enquote{\texttt{show}} functions.
 %    \begin{macrocode}
-\__kernel_msg_new:nnn { clist } { show }
+\msg_new:nnn { clist } { show }
   {
     The~comma~list~ \tl_if_empty:nF {#1} { #1 ~ }
     \tl_if_empty:nTF {#2}
       { is~empty \\>~ . }
       { contains~the~items~(without~outer~braces): #2 . }
   }
-\__kernel_msg_new:nnn { intarray } { show }
+\msg_new:nnn { intarray } { show }
   { The~integer~array~#1~contains~#2~items: \\ #3 . }
-\__kernel_msg_new:nnn { prop } { show }
+\msg_new:nnn { prop } { show }
   {
     The~property~list~#1~
     \tl_if_empty:nTF {#2}
       { is~empty \\>~ . }
       { contains~the~pairs~(without~outer~braces): #2 . }
   }
-\__kernel_msg_new:nnn { seq } { show }
+\msg_new:nnn { seq } { show }
   {
     The~sequence~#1~
     \tl_if_empty:nTF {#2}
       { is~empty \\>~ . }
       { contains~the~items~(without~outer~braces): #2 . }
   }
-\__kernel_msg_new:nnn { kernel } { show-streams }
+\msg_new:nnn { kernel } { show-streams }
   {
     \tl_if_empty:nTF {#2} { No~ } { The~following~ }
     \str_case:nn {#1}
@@ -2174,13 +2031,13 @@
 %
 % System layer messages
 %    \begin{macrocode}
-\__kernel_msg_new:nnnn { sys } { backend-set }
+\msg_new:nnnn { sys } { backend-set }
   { Backend~configuration~already~set. }
   {
     Run-time~backend~selection~may~only~be~carried~out~once~during~a~run.~
     This~second~attempt~to~set~them~will~be~ignored.
   }
-\__kernel_msg_new:nnnn { sys } { wrong-backend }
+\msg_new:nnnn { sys } { wrong-backend }
   { Backend~request~inconsistent~with~engine:~using~'#2'~backend. }
   {
     You~have~requested~backend~'#1',~but~this~is~not~suitable~for~use~with~the~
@@ -2190,104 +2047,31 @@
 %
 % \subsection{Expandable errors}
 %
-% \begin{macro}{\@@_expandable_error:n}
-% \begin{macro}{\@@_expandable_error:w}
+% \begin{macro}{\@@_expandable_error:nn}
 %   In expansion only context, we cannot use the normal means of
-%   reporting errors. Instead, we feed \TeX{} an undefined control
-%   sequence, \cs[module = {}]{LaTeX3 error:}. It is thus interrupted, and shows
+%   reporting errors. Instead, we rely on a low-level \TeX{} error
+%   caused by expanding a macro \cs{???} with parameter text ``|?|''
+%   (this could be any token) which we used followed by something else
+%   (here, a space).  This shows
 %   the context, which thanks to the odd-looking \cs{use:n} is
 %   \begin{verbatim}
-%     <argument> \LaTeX3 error:
-%                               The error message.
+%     <argument> \???
+%                     ! mypkg Error: The error message.
 %   \end{verbatim}
 %   In other words, \TeX{} is processing the argument of \cs{use:n},
-%   which is \cs[module = {}]{LaTeX3 error:} \meta{error message}.
-%   Then \cs{@@_expandable_error:w} cleans up. In fact, there
-%   is an extra subtlety: if the user inserts tokens for error recovery,
-%   they should be kept. Thus we also use an odd space character
-%   (with category code $7$) and keep tokens until that space character,
-%   dropping everything else until \cs{s_@@_stop}. The \cs{exp_end:} prevents
-%   losing braces around the user-inserted text if any, and stops the
-%   expansion of \cs{exp:w}.  The group is used to prevent
-%   |\LaTeX3~error:| from being globally equal to \cs{scan_stop:}.
+%   which is \cs{???} \meta{space} |!| \meta{error type} |:| \meta{error message}.
 %    \begin{macrocode}
-\group_begin:
-\cs_set_protected:Npn \@@_tmp:w #1#2
+\cs_set_protected:Npn \@@_tmp:w #1
   {
-    \cs_new:Npn \@@_expandable_error:n ##1
+    \cs_new:Npn #1 ? { }
+    \cs_new:Npn \@@_expandable_error:nn ##1##2
       {
-        \exp:w
         \exp_after:wN \exp_after:wN
-        \exp_after:wN \@@_expandable_error:w
-        \exp_after:wN \exp_after:wN
-        \exp_after:wN \exp_end:
-        \use:n { #1 #2 ##1 } #2
+        \exp_after:wN \@@_use_none_delimit_by_s_stop:w
+        \use:n { #1 ~ ! ~ ##2 : ~ ##1 } \s_@@_stop
       }
-    \cs_new:Npn \@@_expandable_error:w ##1 #2 ##2 #2 {##1}
   }
-\exp_args:Ncx \@@_tmp:w { LaTeX3~error: }
-  { \char_generate:nn { `\  } { 7 } }
-\group_end:
-%    \end{macrocode}
-% \end{macro}
-% \end{macro}
-%
-% \begin{macro}
-%   {
-%     \__kernel_msg_expandable_error:nnnnnn,
-%     \__kernel_msg_expandable_error:nnnnn,
-%     \__kernel_msg_expandable_error:nnnn,
-%     \__kernel_msg_expandable_error:nnn,
-%     \__kernel_msg_expandable_error:nn,
-%     \__kernel_msg_expandable_error:nnffff,
-%     \__kernel_msg_expandable_error:nnfff,
-%     \__kernel_msg_expandable_error:nnff,
-%     \__kernel_msg_expandable_error:nnf,
-%   }
-%   The command built from the csname
-%   \cs{c_@@_text_prefix_tl} |LaTeX / #1 / #2|
-%   takes four arguments and builds the error text, which is fed to
-%   \cs{@@_expandable_error:n} with appropriate expansion: just as for
-%   usual messages the arguments are first turned to strings, then the
-%   message is fully expanded.
-%    \begin{macrocode}
-\exp_args_generate:n { oooo }
-\cs_new:Npn \__kernel_msg_expandable_error:nnnnnn #1#2#3#4#5#6
-  {
-    \exp_args:Ne \@@_expandable_error:n
-      {
-        \exp_args:Nc \exp_args:Noooo
-          { \c_@@_text_prefix_tl LaTeX / #1 / #2 }
-          { \tl_to_str:n {#3} }
-          { \tl_to_str:n {#4} }
-          { \tl_to_str:n {#5} }
-          { \tl_to_str:n {#6} }
-      }
-  }
-\cs_new:Npn \__kernel_msg_expandable_error:nnnnn #1#2#3#4#5
-  {
-    \__kernel_msg_expandable_error:nnnnnn
-      {#1} {#2} {#3} {#4} {#5} { }
-  }
-\cs_new:Npn \__kernel_msg_expandable_error:nnnn #1#2#3#4
-  {
-    \__kernel_msg_expandable_error:nnnnnn
-      {#1} {#2} {#3} {#4} { } { }
-  }
-\cs_new:Npn \__kernel_msg_expandable_error:nnn #1#2#3
-  {
-    \__kernel_msg_expandable_error:nnnnnn
-      {#1} {#2} {#3} { } { } { }
-  }
-\cs_new:Npn \__kernel_msg_expandable_error:nn #1#2
-  {
-    \__kernel_msg_expandable_error:nnnnnn
-      {#1} {#2} { } { } { } { }
-  }
-\cs_generate_variant:Nn \__kernel_msg_expandable_error:nnnnnn { nnffff }
-\cs_generate_variant:Nn \__kernel_msg_expandable_error:nnnnn { nnfff }
-\cs_generate_variant:Nn \__kernel_msg_expandable_error:nnnn { nnff }
-\cs_generate_variant:Nn \__kernel_msg_expandable_error:nnn { nnf }
+\exp_args:Nc \@@_tmp:w { ??? }
 %    \end{macrocode}
 % \end{macro}
 %
@@ -2303,12 +2087,17 @@
 %     \msg_expandable_error:nnff   ,
 %     \msg_expandable_error:nnf
 %   }
-% \begin{macro}{\@@_expandable_error_module:nn}
-%   Pass to an auxiliary the message to display and the module name
+%   The command built from the csname
+%   \cs{c_@@_text_prefix_tl} |#1 / #2|
+%   takes four arguments and builds the error text, which is fed to
+%   \cs{@@_expandable_error:n} with appropriate expansion: just as for
+%   usual messages the arguments are first turned to strings, then the
+%   message is fully expanded.  The module name also has to be determined.
 %    \begin{macrocode}
+\exp_args_generate:n { oooo }
 \cs_new:Npn \msg_expandable_error:nnnnnn #1#2#3#4#5#6
   {
-    \exp_args:Ne \@@_expandable_error_module:nn
+    \exp_args:Nee \@@_expandable_error:nn
       {
         \exp_args:Nc \exp_args:Noooo
           { \c_@@_text_prefix_tl #1 / #2 }
@@ -2317,7 +2106,7 @@
           { \tl_to_str:n {#5} }
           { \tl_to_str:n {#6} }
       }
-      {#1}
+      { \msg_error_text:n {#1} }
   }
 \cs_new:Npn \msg_expandable_error:nnnnn #1#2#3#4#5
   { \msg_expandable_error:nnnnnn {#1} {#2} {#3} {#4} {#5} { } }
@@ -2331,15 +2120,28 @@
 \cs_generate_variant:Nn \msg_expandable_error:nnnnn  { nnfff }
 \cs_generate_variant:Nn \msg_expandable_error:nnnn   { nnff }
 \cs_generate_variant:Nn \msg_expandable_error:nnn    { nnf }
-\cs_new:Npn \@@_expandable_error_module:nn #1#2
+%    \end{macrocode}
+% \end{macro}
+%
+% \subsection{Message formatting}
+%
+%    \begin{macrocode}
+\prop_gput:Nnn \g_msg_module_name_prop { kernel } { LaTeX3 }
+\prop_gput:Nnn \g_msg_module_type_prop { kernel } { }
+\clist_map_inline:nn
   {
-    \exp_after:wN \exp_after:wN
-    \exp_after:wN \@@_use_none_delimit_by_s_stop:w
-    \use:n { \::error ! ~ #2 : ~ #1 } \s_@@_stop
+    char , clist , coffin , debug , deprecation , msg ,
+    quark , prg , prop , scanmark , seq , sys
   }
+  {
+    \prop_gput:Nnn \g_msg_module_name_prop {#1} { LaTeX3 }
+    \prop_gput:Nnn \g_msg_module_type_prop {#1} { }
+  }
+\prop_gput:Nnn \g_msg_module_name_prop { LaTeX / cmd } { LaTeX3 }
+\prop_gput:Nnn \g_msg_module_type_prop { LaTeX / cmd } { }
+\prop_gput:Nnn \g_msg_module_name_prop { LaTeX / ltcmd } { LaTeX3 }
+\prop_gput:Nnn \g_msg_module_type_prop { LaTeX / ltcmd } { }
 %    \end{macrocode}
-% \end{macro}
-% \end{macro}
 %
 %    \begin{macrocode}
 %</package>