nl: promptly diagnose write errors

* NEWS: Mention the improvement.
* src/nl.c (process_file): Exit if error outputting line.
* tests/misc/write-errors.sh: Enable the test case.

NEWS

@@ -43,7 +43,7 @@ GNU coreutils NEWS                                    -*- outline -*-
 
 ** Improvements
 
-  'fmt' will now exit promptly upon receiving a write error,
+  'fmt' and 'nl' will now exit promptly upon receiving a write error,
   which is significant when reading large / unbounded inputs.
 
   'install' now uses posix_spawn() to invoke the strip program more efficiently.

src/nl.c

@@ -425,6 +425,9 @@ process_file (FILE *fp)
           proc_text ();
           break;
         }
+
+      if (ferror (stdout))
+        write_error ();
     }
 }
 

tests/misc/write-errors.sh

@@ -41,7 +41,7 @@ fold -c /dev/zero
 fold --version; yes | tr -d '\\n' | fold
 head -z -n-1 /dev/zero
 join -a 1 -z /dev/zero /dev/null
-# TODO: nl --version; yes | nl
+nl --version; yes | nl
 numfmt --version; yes 1 | numfmt
 od -v /dev/zero
 paste /dev/zero