doc: mcel: give more detail on error interface

* lib/mcel.h: Mention that errors may be given on
some systems even with the "C" locale, as mcel
has explicitly disabled the workaround for:
https://sourceware.org/PR29511
Also state that len is set to 1 on any error.

diff --git a/ChangeLog b/ChangeLog
index 1d2195ca0fa6bec45e8a6254b27fb5bf5a7d021e..13c9a9e96eacaa0af72ef60d4711b744572ecd95 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2025-11-01  Pádraig Brady  <P@draigBrady.com>
+
+       doc: mcel: give more detail on error interface
+       * lib/mcel.h: Mention that errors may be given on
+       some systems even with the "C" locale, as mcel
+       has explicitly disabled the workaround for:
+       https://sourceware.org/PR29511
+       Also state that len is set to 1 on any error.
+
 2025-11-01  Paul Eggert  <eggert@cs.ucla.edu>
 
        nstrftime: do not return PTRDIFF_MAX

diff --git a/lib/mcel.h b/lib/mcel.h
index ebdd135f63af58291597c2921d57fc88c774b00d..3e770c8c6089a35448b643f26d95ccdf82f942e9 100644 (file)
--- a/lib/mcel.h
+++ b/lib/mcel.h
@@ -45,6 +45,8 @@
 
    You can select from G using G.ch, G.err, and G.len.
    G is an encoding error if G.err is nonzero, a character otherwise.
+   Note G.err may occur even in the "C" locale on some systems.
+   In any case G.len will be 1 if G.err is set.
 
    The mcel_scanz function is similar except it works with a
    string of unknown but positive length that is terminated with '\0'.