Support two-character font names (BI, CW, CR, CB, CI)

in the tbl(7) layout font modifier.

Get rid of the TBL_CELL_BOLD and TBL_CELL_ITALIC flags and use
the usual ESCAPE_FONT* enum mandoc_esc members from mandoc.h instead,
which simplifies and unifies some code.

While here, also support CB and CI in roff(7) \f escape sequences
and in roff(7) .ft requests for all output modes.  Using those is
certainly not recommended because portability is limited even with
groff, but supporting them makes some existing third-party manual
pages look better, in particular in HTML output mode.

Bug-compatible with groff as far as i'm aware, except that i consider
font names starting with the '\n' (ASCII 0x0a line feed) character
so insane that i decided to not support them.

Missing feature reported by nabijaczleweli dot xyz in
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=992002.
I used none of the code from the initial patch submitted by
nabijaczleweli, but some of their ideas.
Final patch tested by them, too.

10 files changed, 55 insertions, 23 deletions

diff --git a/regress/roff/esc/f.out_html b/regress/roff/esc/f.out_html
index 887175f6..30f5c7e1 100644
--- a/regress/roff/esc/f.out_html
+++ b/regress/roff/esc/f.out_html
@@ -1,4 +1,4 @@
 numbers: <b><i>bolditalic</i></b><b>bold</b><i>italic</i>roman
 letters: <b>bold</b><i>italic</i><b>back</b><b><i>bolditalic</i></b>roman
 multiletter: <b>bold</b>empty<i>italic</i>back<b><i>bolditalic</i></b>roman
-typewriter: <span class="Li">roman</span><b>bold</b><span class="Li">roman</span><i>italic</i>roman
+typewriter: <span class="Li">roman</span><span class="Li"><b>bold</b></span><span class="Li">roman</span><span class="Li"><i>italic</i></span>roman
diff --git a/regress/roff/ft/badargs.out_html b/regress/roff/ft/badargs.out_html
index a332e3a2..686ca476 100644
--- a/regress/roff/ft/badargs.out_html
+++ b/regress/roff/ft/badargs.out_html
@@ -1,6 +1,7 @@
   <br/>
   default font <i>italic</i> <b><i>bold italic</i></b>
-    <span class="Li">typeqriter</span> <span class="Li">roman</span> <b>bold</b>
-    <i>italic</i> <b>bold</b> <b>still bold</b> <i>italic</i> <i>back to
-    bold</i> <i>back to italic</i>
+    <span class="Li">typeqriter</span> <span class="Li">roman</span>
+    <span class="Li"><b>bold</b></span> <span class="Li"><i>italic</i></span>
+    <b>bold</b> <b>still bold</b> <i>italic</i> <i>back to bold</i> <i>back to
+    italic</i>
   <br/>
diff --git a/regress/tbl/mod/Makefile b/regress/tbl/mod/Makefile
index 96547d64..7bbf30e5 100644
--- a/regress/tbl/mod/Makefile
+++ b/regress/tbl/mod/Makefile
@@ -1,15 +1,16 @@
-# $OpenBSD: Makefile,v 1.2 2015/02/10 11:02:19 schwarze Exp $
+# $OpenBSD: Makefile,v 1.6 2021/08/10 12:36:42 schwarze Exp $
 
-REGRESS_TARGETS	 = badfont expand expand-toowide font misalign spacing width
-LINT_TARGETS	 = badfont font
+REGRESS_TARGETS	 = badfont expand expand-toowide font font-eol
+REGRESS_TARGETS	+= misalign spacing width
+LINT_TARGETS	 = badfont font font-eol
 
-# groff-1.22.3 defects:
+# groff-1.22.4 defects:
 # - The "f" font modifier swallows a following newline character.
 # - When space is insufficient (on either side) for properly aligning
 #   a number, GNU tbl(1) moves the number too much to the right,
 #   overflowing the column, even if space would be sufficient without
 #   left padding.
 
-SKIP_GROFF	 = badfont misalign
+SKIP_GROFF	 = font-eol misalign
 
 .include <bsd.regress.mk>
diff --git a/regress/tbl/mod/badfont.in b/regress/tbl/mod/badfont.in
index 2a4f0d0a..12303149 100644
--- a/regress/tbl/mod/badfont.in
+++ b/regress/tbl/mod/badfont.in
@@ -1,15 +1,17 @@
-.\" $OpenBSD: badfont.in,v 1.2 2017/07/04 14:53:27 schwarze Exp $
-.TH TBL-MOD-BADFONT 1 "February 10, 2015"
+.\" $OpenBSD: badfont.in,v 1.3 2021/08/10 12:36:42 schwarze Exp $
+.TH TBL-MOD-BADFONT 1 "August 9, 2021"
 .SH NAME
 tbl-mod-badfont \- invalid font modifiers in table layouts
 .SH DESCRIPTION
 normal text
 .TS
 box tab(:);
-lfB lf
+lfI lfX
+lfB lfIB
 lfI lf.
 lfB lfI.
-bold:none
-italic:none
+italic:one char
+bold:two chars
+italic:dot
 bold:italic
 .TE
diff --git a/regress/tbl/mod/badfont.out_ascii b/regress/tbl/mod/badfont.out_ascii
index 43683330..4cd3bd3f 100644
--- a/regress/tbl/mod/badfont.out_ascii
+++ b/regress/tbl/mod/badfont.out_ascii
@@ -6,9 +6,10 @@ NNAAMMEE
 DDEESSCCRRIIPPTTIIOONN
        normal text
 
-       +----------------+
-       |bboolldd     none   |
-       |_i_t_a_l_i_c   none   |
-       |bboolldd     _i_t_a_l_i_c |
-       +----------------+
-OpenBSD                        February 10, 2015            TBL-MOD-BADFONT(1)
+       +-------------------+
+       |_i_t_a_l_i_c   one char  |
+       |bboolldd     two chars |
+       |_i_t_a_l_i_c   dot       |
+       |bboolldd     _i_t_a_l_i_c    |
+       +-------------------+
+OpenBSD                         August 9, 2021              TBL-MOD-BADFONT(1)
diff --git a/regress/tbl/mod/badfont.out_lint b/regress/tbl/mod/badfont.out_lint
index c19bae82..7884ec88 100644
--- a/regress/tbl/mod/badfont.out_lint
+++ b/regress/tbl/mod/badfont.out_lint
@@ -1,2 +1,3 @@
-mandoc: badfont.in:9:7: WARNING: unknown font, skipping request: TS f
-mandoc: badfont.in:10:7: WARNING: unknown font, skipping request: TS f.
+mandoc: badfont.in:9:7: WARNING: unknown font, skipping request: TS fX
+mandoc: badfont.in:10:7: WARNING: unknown font, skipping request: TS fIB
+mandoc: badfont.in:11:7: WARNING: unknown font, skipping request: TS f.
diff --git a/regress/tbl/mod/font-eol.in b/regress/tbl/mod/font-eol.in
new file mode 100644
index 00000000..fadf66ec
--- /dev/null
+++ b/regress/tbl/mod/font-eol.in
@@ -0,0 +1,13 @@
+.\" $OpenBSD: font-eol.in,v 1.1 2021/08/10 12:36:42 schwarze Exp $
+.TH TBL-MOD-FONT-EOL 1 "August 9, 2021"
+.SH NAME
+tbl-mod-font-eol \- font modifier at eol in table layout
+.SH DESCRIPTION
+normal text
+.TS
+box tab(:);
+lfB lf
+lfB lfI.
+bold:none
+bold:italic
+.TE
diff --git a/regress/tbl/mod/font-eol.out_ascii b/regress/tbl/mod/font-eol.out_ascii
new file mode 100644
index 00000000..c87d5aba
--- /dev/null
+++ b/regress/tbl/mod/font-eol.out_ascii
@@ -0,0 +1,13 @@
+TBL-MOD-FONT-EOL(1)         General Commands Manual        TBL-MOD-FONT-EOL(1)
+
+NNAAMMEE
+       tbl-mod-font-eol - font modifier at eol in table layout
+
+DDEESSCCRRIIPPTTIIOONN
+       normal text
+
+       +--------------+
+       |bboolldd   none   |
+       |bboolldd   _i_t_a_l_i_c |
+       +--------------+
+OpenBSD                         August 9, 2021             TBL-MOD-FONT-EOL(1)
diff --git a/regress/tbl/mod/font-eol.out_lint b/regress/tbl/mod/font-eol.out_lint
new file mode 100644
index 00000000..c7f83f34
--- /dev/null
+++ b/regress/tbl/mod/font-eol.out_lint
@@ -0,0 +1 @@
+mandoc: font-eol.in:9:7: WARNING: unknown font, skipping request: TS f
diff --git a/regress/tbl/mod/font.out_lint b/regress/tbl/mod/font.out_lint
index 06046a43..7ddd6280 100644
--- a/regress/tbl/mod/font.out_lint
+++ b/regress/tbl/mod/font.out_lint
@@ -1,4 +1,3 @@
-mandoc: font.in:9:6: WARNING: unknown font, skipping request: TS fCW|ci
 mandoc: font.in:19:2: WARNING: tab in filled text
 mandoc: font.in:19:4: WARNING: tab in filled text
 mandoc: font.in:19:6: WARNING: tab in filled text