Surprisingly, every escape sequence can also be used as an argument

delimiter for an outer escape sequence, in which case the delimiting
escape sequence retains its syntax but usually ignores its argument
and loses its inherent effect.  Add rudimentary support for this
syntax quirk in order to improve parsing compatibility with groff.

1 files changed, 47 insertions, 2 deletions

diff --git a/regress/roff/esc/B.out_ascii b/regress/roff/esc/B.out_ascii
index 805b0641..d42a6901 100644
--- a/regress/roff/esc/B.out_ascii
+++ b/regress/roff/esc/B.out_ascii
@@ -18,6 +18,51 @@ DDEESSCCRRIIPPTTIIOONN
      parentheses containing number: 1
      complex expression: 1
      other delimiter: 1
-     no closing delimiter: 0
 
-OpenBSD                          July 4, 2017                          OpenBSD
+   AArrgguummeenntt ddeelliimmiitteerrss
+     unsupported \!: 1u
+     unsupported \r: 042u
+     ignored \%: 1u
+     ignored \&: 1u
+     ignored \): 1u
+     ignored \,: 042u
+     ignored \/: 1u
+     ignored \^: 042u
+     ignored \a: 042u
+     ignored \d: 042u
+     ignored \t: 042u
+     ignored \u: 042u
+     ignored \{: 1u
+     ignored \|: 042u
+     ignored \}: 1u
+     useless \.: 042.u
+     invalid \G: 1u
+     special \ : 042 u
+     special \': 1u
+     special \-: 1u
+     special \0: 042 u
+     special \:: 1u
+     special \_: 1u
+     special \`: 1u
+     special \e: 1u
+     special \~: 042 u
+     break \p: 1u
+     nospace \c: 1u
+     string expansion: 1u
+     register expansion: 03u
+     ignored \O: 042u
+     ignored \Y: 042u
+     ignored \k: 1u
+     special character: 1u
+     ignored \D: 042u
+     ignored \L: 042u
+     ignored \X: 042u
+     ignored \Z: 042u
+     ignored \b: 042u
+     ignored \v: 042u
+     ignored \x: 042u
+     horizontal motion: 042   u
+     horizontal line: 042__u
+     overstrike: 042cdu
+
+OpenBSD                          June 8, 2022                          OpenBSD