+AT_BISON_CHECK([[input.y]], [[1]], [[]],
+[[<skeleton default value>: error: invalid value for %define Boolean variable 'foo'
+]])
+
+AT_CLEANUP
+
+
+## --------------------------------------------- ##
+## Complaining during macro argument expansion. ##
+## --------------------------------------------- ##
+
+AT_SETUP([[Complaining during macro argument expansion]])
+
+AT_DATA([[skel1.c]],
+[[m4@&t@_define([foow], [b4_warn([[foow fubar]])])
+m4@&t@_define([foowat], [b4_warn_at([[foow.y:2.3]],
+ [[foow.y:5.4]], [[foowat fubar]])])
+m4@&t@_define([fooc], [b4_complain([[fooc fubar]])])
+m4@&t@_define([foocat], [b4_complain_at([[fooc.y:1.1]],
+ [[fooc.y:10.6]], [[foocat fubar]])])
+m4@&t@_define([foof], [b4_fatal([[foof fubar]])])
+m4@&t@_if(foow, [1], [yes])
+m4@&t@_if(foowat, [1], [yes])
+m4@&t@_if(fooc, [1], [yes])
+m4@&t@_if(foocat, [1], [yes])
+m4@&t@_if(foof, [1], [yes])
+]])
+
+AT_DATA([[input1.y]],
+[[%skeleton "./skel1.c"
+%%
+start: ;
+]])
+
+AT_BISON_CHECK([[input1.y]], [[1]], [[]],
+[[input1.y: warning: foow fubar [-Wother]
+foow.y:2.3-5.3: warning: foowat fubar [-Wother]
+input1.y: error: fooc fubar
+fooc.y:1.1-10.5: error: foocat fubar
+input1.y: fatal error: foof fubar
+]])
+
+AT_DATA([[skel2.c]],
+[[m4@&t@_define([foofat], [b4_fatal_at([[foof.y:12.11]],
+ [[foof.y:100.123]], [[foofat fubar]])])
+m4@&t@_if(foofat, [1], [yes])
+]])
+
+AT_DATA([[input2.y]],
+[[%skeleton "./skel2.c"
+%%
+start: ;
+]])
+
+AT_BISON_CHECK([[input2.y]], [[1]], [[]],
+[[foof.y:12.11-100.122: fatal error: foofat fubar
+]])
+
+AT_DATA([[skel3.c]],
+[[b4_complain_at(b4_percent_define_get_loc([[bogus]]), [[bad value]])
+]])
+
+AT_DATA([[input3.y]],
+[[%skeleton "./skel3.c"
+%%
+start: ;
+]])
+
+AT_BISON_CHECK([[input3.y]], [[1]], [[]],
+[[input3.y: fatal error: b4_percent_define_get_loc: undefined %define variable 'bogus'
+]])
+
+AT_DATA([[skel4.c]],
+[[b4_warn_at(b4_percent_define_get_syncline([[bogus]]), [[bad value]])
+]])
+
+AT_DATA([[input4.y]],
+[[%skeleton "./skel4.c"
+%%
+start: ;
+]])
+
+AT_BISON_CHECK([[input4.y]], [[1]], [[]],
+[[input4.y: fatal error: b4_percent_define_get_syncline: undefined %define variable 'bogus'
+]])
+
+AT_CLEANUP
+
+
+## --------------------------------------- ##
+## Fatal errors make M4 exit immediately. ##
+## --------------------------------------- ##
+
+AT_SETUP([[Fatal errors make M4 exit immediately]])
+
+AT_DATA([[skel1.c]],
+[[b4_complain([[non-fatal error]])
+b4_fatal([[M4 should exit immediately here]])
+m4@&t@_fatal([this should never be evaluated])
+]])
+
+AT_DATA([[input1.y]],
+[[%skeleton "./skel1.c"
+%%
+start: ;
+]])
+
+AT_BISON_CHECK([[input1.y]], [[1]], [[]],
+[[input1.y: error: non-fatal error
+input1.y: fatal error: M4 should exit immediately here
+]])
+
+AT_DATA([[skel2.c]],
+[[b4_warn([[morning]])
+b4_fatal_at([[foo.y:1.5]], [[foo.y:1.7]], [[M4 should exit immediately here]])
+m4@&t@_fatal([this should never be evaluated])
+]])
+
+AT_DATA([[input2.y]],
+[[%skeleton "./skel2.c"
+%%
+start: ;
+]])
+
+AT_BISON_CHECK([[input2.y]], [[1]], [[]],
+[[input2.y: warning: morning [-Wother]
+foo.y:1.5-6: fatal error: M4 should exit immediately here
+]])
+
+AT_CLEANUP
+
+
+## ------------------------------------------------ ##
+## Fatal errors but M4 continues producing output. ##
+## ------------------------------------------------ ##
+
+# At one time, if Bison encountered a fatal error during M4 processing,
+# Bison failed to drain M4's output pipe. The result was a SIGPIPE.
+# On some platforms, the default disposition for SIGPIPE is terminate,
+# which was fine. On others, it's ignore, which caused M4 to report
+# the broken pipe to the user, but we don't want to bother the user with
+# that.
+
+# There is a race condition somewhere. That is, before the associated
+# fix, running this test group many times in a row would occasionally
+# produce a pass among all the failures.
+
+AT_SETUP([[Fatal errors but M4 continues producing output]])
+
+AT_DATA([[gen-skel.pl]],
+[[use warnings;
+use strict;
+my $M4 = "m4";
+my $DNL = "d"."nl";
+print "${M4}_divert_push(0)$DNL\n";
+print '@output(@,@)', "\n";
+(print "garbage"x10, "\n") for (1..1000);
+print "${M4}_divert_pop(0)\n";
+]])
+AT_CHECK([[$PERL gen-skel.pl > skel.c || exit 77]])
+
+AT_DATA([[input.y]],
+[[%skeleton "./skel.c"
+%%
+start: ;