During identifier parsing, handle undefined escape sequences

in the same way as groff:
* \\ is always reduced to \
* \. is always reduced to .
* other undefined escape sequences are usually reduced to the escape name,
for example \G to G, except during the expansion of expanding escape
sequences having the standard argument form (in particular \* and \n),
in which case the backslash is preserved literally.

Yes, this is confusing indeed.
For example, the following have the same meaning:
* .ds \.   and   .ds .     which is not the same as   .ds \\.
* \*[\.]   and   \*[.]     which is not the same as   \*[\\.]
* .ds \G   and   .ds G     which is not the same as   .ds \\G
* \*[\G]   and   \*[\\G]   which is not the same as   \*[G]   <- sic!

To feel less dirty, have a leaning toothpick, if you are so inclined.

This patch also slightly improves the string shown by the "escaped
character not allowed in a name" error message.

diff --git a/regress/usr.bin/mandoc/roff/args/man.out_lint b/regress/usr.bin/mandoc/roff/args/man.out_lint
index 6d6bbd8..5aaebd9 100644 (file)
--- a/regress/usr.bin/mandoc/roff/args/man.out_lint
+++ b/regress/usr.bin/mandoc/roff/args/man.out_lint
@@ -6,4 +6,4 @@ mandoc: man.in:87:26: STYLE: whitespace at end of input line
 mandoc: man.in:91:27: STYLE: whitespace at end of input line
 mandoc: man.in:104:5: STYLE: unterminated quoted argument
 mandoc: man.in:107:9: STYLE: unterminated quoted argument
-mandoc: man.in:131:1: ERROR: escaped character not allowed in a name: IB\(
+mandoc: man.in:131:1: ERROR: escaped character not allowed in a name: IB\(lq

diff --git a/regress/usr.bin/mandoc/roff/args/mdoc.out_lint b/regress/usr.bin/mandoc/roff/args/mdoc.out_lint
index 4422d75..1691cf2 100644 (file)
--- a/regress/usr.bin/mandoc/roff/args/mdoc.out_lint
+++ b/regress/usr.bin/mandoc/roff/args/mdoc.out_lint
@@ -14,4 +14,4 @@ mandoc: mdoc.in:112:5: STYLE: unterminated quoted argument
 mandoc: mdoc.in:112:11: STYLE: whitespace at end of input line
 mandoc: mdoc.in:113:9: STYLE: unterminated quoted argument
 mandoc: mdoc.in:113:15: STYLE: whitespace at end of input line
-mandoc: mdoc.in:121:1: ERROR: escaped character not allowed in a name: Fl\(
+mandoc: mdoc.in:121:1: ERROR: escaped character not allowed in a name: Fl\(lq

diff --git a/regress/usr.bin/mandoc/roff/cond/register.in b/regress/usr.bin/mandoc/roff/cond/register.in
index 879c573..7f137c9 100644 (file)
--- a/regress/usr.bin/mandoc/roff/cond/register.in
+++ b/regress/usr.bin/mandoc/roff/cond/register.in
@@ -1,5 +1,5 @@
-.\" $OpenBSD: register.in,v 1.3 2019/02/06 20:54:28 schwarze Exp $
-.TH REGISTER 1 "February 6, 2019"
+.\" $OpenBSD: register.in,v 1.4 2022/06/03 11:50:25 schwarze Exp $
+.TH REGISTER 1 "June 3, 2022"
 .SH NAME
 register \- conditional testing whether a register is defined
 .SH DESCRIPTION
@@ -11,10 +11,35 @@ register \- conditional testing whether a register is defined
 .el OOPS
 .if !rmyreg OOPS
 .PP
-identifier + identifier:
+tab after identifier:
 .ie rmyreg     myreg is defined
 .el OOPS
 .PP
 escape sequence after identifier:
 .ie rmyreg\(enmyreg is defined
 .el OOPS
+.PP
+backslash in name:
+.nr \\ 0
+.ie r\\ \e is defined
+.el OOPS
+.rr \\
+.if r\\ is still defined!?
+.PP
+dot in name:
+.nr . 0
+.ie r. \&. is defined
+.el OOPS
+.ie r\. \e. is defined
+.el OOPS
+.rr \.
+.if r. is still defined!?
+.PP
+invalid escape in name:
+.nr G 0
+.ie rG G is defined
+.el OOPS
+.ie r\G \eG is defined
+.el OOPS
+.rr \G
+.if rG is still defined!?

diff --git a/regress/usr.bin/mandoc/roff/cond/register.out_ascii b/regress/usr.bin/mandoc/roff/cond/register.out_ascii
index 928c613..673b9f1 100644 (file)
--- a/regress/usr.bin/mandoc/roff/cond/register.out_ascii
+++ b/regress/usr.bin/mandoc/roff/cond/register.out_ascii
@@ -7,8 +7,14 @@ D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
        not yet defined
        now defined
 
-       identifier + identifier:      myreg is defined
+       tab after identifier:    myreg is defined
 
        escape sequence after identifier: -myreg is defined
 
-OpenBSD                        February 6, 2019                    REGISTER(1)
+       backslash in name: \ is defined
+
+       dot in name: . is defined \. is defined
+
+       invalid escape in name: G is defined \G is defined
+
+OpenBSD                          June 3, 2022                      REGISTER(1)

diff --git a/regress/usr.bin/mandoc/roff/cond/string.in b/regress/usr.bin/mandoc/roff/cond/string.in
index 273984b..fedb4d8 100644 (file)
--- a/regress/usr.bin/mandoc/roff/cond/string.in
+++ b/regress/usr.bin/mandoc/roff/cond/string.in
@@ -1,5 +1,5 @@
-.\" $OpenBSD: string.in,v 1.4 2019/02/06 20:54:28 schwarze Exp $
-.TH STRING 1 "February 6, 2019"
+.\" $OpenBSD: string.in,v 1.5 2022/06/03 11:50:25 schwarze Exp $
+.TH STRING 1 "June 3, 2022"
 .SH NAME
 string \- conditional testing whether a string is defined
 .SH DESCRIPTION
@@ -40,3 +40,28 @@ identifier and tab:
 escape sequence after identifier:
 .ie d mystr\(enmystr is defined
 .el OOPS
+.PP
+backslash in name:
+.ds \\ value
+.ie d \\ \e is defined
+.el OOPS
+.rm \\
+.if d \\ still defined!?
+.PP
+dot in name:
+.ds . value
+.ie d . \&. is defined
+.el OOPS
+.ie d \. \e. is defined
+.el OOPS
+.rm .
+.if d . still defined!?
+.PP
+invalid escape in name:
+.ds G value
+.ie d G G is defined
+.el OOPS
+.ie d \G \eG is defined
+.el OOPS
+.rm \G
+.if d G still defined!?

diff --git a/regress/usr.bin/mandoc/roff/cond/string.out_ascii b/regress/usr.bin/mandoc/roff/cond/string.out_ascii
index 2d80a90..c67c0c5 100644 (file)
--- a/regress/usr.bin/mandoc/roff/cond/string.out_ascii
+++ b/regress/usr.bin/mandoc/roff/cond/string.out_ascii
@@ -19,4 +19,10 @@ D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
 
        escape sequence after identifier: -mystr is defined
 
-OpenBSD                        February 6, 2019                      STRING(1)
+       backslash in name: \ is defined
+
+       dot in name: . is defined \. is defined
+
+       invalid escape in name: G is defined \G is defined
+
+OpenBSD                          June 3, 2022                        STRING(1)

diff --git a/regress/usr.bin/mandoc/roff/de/escname.in b/regress/usr.bin/mandoc/roff/de/escname.in
index 67d2609..99305ea 100644 (file)
--- a/regress/usr.bin/mandoc/roff/de/escname.in
+++ b/regress/usr.bin/mandoc/roff/de/escname.in
@@ -1,5 +1,5 @@
-.\" $OpenBSD: escname.in,v 1.4 2017/07/04 14:53:27 schwarze Exp $
-.Dd $Mdocdate: July 4 2017 $
+.\" $OpenBSD: escname.in,v 1.5 2022/06/03 11:50:25 schwarze Exp $
+.Dd $Mdocdate: June 3 2022 $
 .Dt DE-ESCNAME 1
 .Os
 .Sh NAME
@@ -23,10 +23,33 @@ define first = val1
 val1
 ..
 .Pp
-Values (first, second, first\esecond):
+define first\e.second = val_dot
+.de first\.second
+val_dot
+..
+.Pp
+define first\eGsecond = val_inval
+.de first\Gsecond
+val_inval
+..
+.Pp
+Values:
+.Bl -tag -width first_.second -compact
+.It first
 .first
+.It second
 .second
+.It first\esecond
 .first\\second
+.It first.second
+.first.second
+.It first\e.second
+.first\.second
+.It firstGsecond
+.firstGsecond
+.It first\eGsecond
+.first\Gsecond
+.El
 .Pp
 Remove all but second:
 .rm first\\second first\esecond second

diff --git a/regress/usr.bin/mandoc/roff/de/escname.out_ascii b/regress/usr.bin/mandoc/roff/de/escname.out_ascii
index 367b5d0..57b8c34 100644 (file)
--- a/regress/usr.bin/mandoc/roff/de/escname.out_ascii
+++ b/regress/usr.bin/mandoc/roff/de/escname.out_ascii
@@ -12,7 +12,18 @@ D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
 
      define first = val1
 
-     Values (first, second, first\second): val1 val2 val3
+     define first\.second = val_dot
+
+     define first\Gsecond = val_inval
+
+     Values:
+     first          val1
+     second         val2
+     first\second   val3
+     first.second   val_dot
+     first\.second  val_dot
+     firstGsecond   val_inval
+     first\Gsecond  val_inval
 
      Remove all but second: val2
 

diff --git a/regress/usr.bin/mandoc/roff/de/escname.out_lint b/regress/usr.bin/mandoc/roff/de/escname.out_lint
index a3f9396..5dba197 100644 (file)
--- a/regress/usr.bin/mandoc/roff/de/escname.out_lint
+++ b/regress/usr.bin/mandoc/roff/de/escname.out_lint
@@ -1,8 +1,10 @@
 mandoc: escname.in:22:2: ERROR: escaped character not allowed in a name: first\e
-mandoc: escname.in:32:19: ERROR: escaped character not allowed in a name: first\e
-mandoc: escname.in:33:2: ERROR: skipping unknown macro: .first
-mandoc: escname.in:35:2: ERROR: skipping unknown macro: .first\\second
-mandoc: escname.in:38:5: ERROR: skipping excess arguments: .de ... excess arguments
-mandoc: escname.in:41:1: ERROR: escaped character not allowed in a name: witharg\(
-mandoc: escname.in:43:1: ERROR: escaped character not allowed in a name: de\e
-mandoc: escname.in:43:2: WARNING: skipping empty request: de
+mandoc: escname.in:32:10: WARNING: undefined escape, printing literally: \G
+mandoc: escname.in:51:7: WARNING: undefined escape, printing literally: \G
+mandoc: escname.in:55:19: ERROR: escaped character not allowed in a name: first\e
+mandoc: escname.in:56:2: ERROR: skipping unknown macro: .first
+mandoc: escname.in:58:2: ERROR: skipping unknown macro: .first\second 
+mandoc: escname.in:61:5: ERROR: skipping excess arguments: .de ... excess arguments
+mandoc: escname.in:64:1: ERROR: escaped character not allowed in a name: witharg\(en
+mandoc: escname.in:66:1: ERROR: escaped character not allowed in a name: de\e
+mandoc: escname.in:66:2: WARNING: skipping empty request: de

diff --git a/regress/usr.bin/mandoc/roff/ds/Makefile b/regress/usr.bin/mandoc/roff/ds/Makefile
index 773105e..68a8b3b 100644 (file)
--- a/regress/usr.bin/mandoc/roff/ds/Makefile
+++ b/regress/usr.bin/mandoc/roff/ds/Makefile
@@ -1,4 +1,9 @@
-# $OpenBSD: Makefile,v 1.6 2019/02/06 20:54:28 schwarze Exp $
+# $OpenBSD: Makefile,v 1.7 2022/06/03 11:50:25 schwarze Exp $
+#
+# This directory is intended for tests of string *definitions*,
+# in particular testing the behaviour of the .ds and .as macros.
+# Tests of string *expansion* are better placed in the roff/string
+# directory.
 
 REGRESS_TARGETS = append escname nested quoting tab
 

diff --git a/regress/usr.bin/mandoc/roff/nr/escname.in b/regress/usr.bin/mandoc/roff/nr/escname.in
index f81627e..d462555 100644 (file)
--- a/regress/usr.bin/mandoc/roff/nr/escname.in
+++ b/regress/usr.bin/mandoc/roff/nr/escname.in
@@ -1,5 +1,5 @@
-.\" $OpenBSD: escname.in,v 1.3 2017/07/04 14:53:27 schwarze Exp $
-.TH NR-ESCNAME 1 "June 29, 2014"
+.\" $OpenBSD: escname.in,v 1.4 2022/06/03 11:50:25 schwarze Exp $
+.TH NR-ESCNAME 1 "June 3, 2022"
 .SH NAME
 nr-escname \- escape sequences in register names
 .SH DESCRIPTION
@@ -7,7 +7,9 @@ nr-escname \- escape sequences in register names
 .nr second 2
 .nr first\\second 3
 .nr first\esecond 4
-\n[first] \n[second] \n[first\\second]
+.nr first\.second 5
+.nr first\Gsecond 6
+\n[first] \n[second] \n[first\\second] \n[first.second] \n[firstGsecond]
 .PP
 .rr first\esecond
 \n[first] \n[second] \n[first\\second]

diff --git a/regress/usr.bin/mandoc/roff/nr/escname.out_ascii b/regress/usr.bin/mandoc/roff/nr/escname.out_ascii
index ca2d50f..d0301af 100644 (file)
--- a/regress/usr.bin/mandoc/roff/nr/escname.out_ascii
+++ b/regress/usr.bin/mandoc/roff/nr/escname.out_ascii
@@ -4,7 +4,7 @@ N\bNA\bAM\bME\bE
        nr-escname - escape sequences in register names
 
 D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
-       1 2 3
+       1 2 3 5 6
 
        0 2 3
 
@@ -12,4 +12,4 @@ D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
 
        incomplete:
 
-OpenBSD                          June 29, 2014                   NR-ESCNAME(1)
+OpenBSD                          June 3, 2022                    NR-ESCNAME(1)

diff --git a/regress/usr.bin/mandoc/roff/nr/escname.out_lint b/regress/usr.bin/mandoc/roff/nr/escname.out_lint
index a2dabeb..edec17f 100644 (file)
--- a/regress/usr.bin/mandoc/roff/nr/escname.out_lint
+++ b/regress/usr.bin/mandoc/roff/nr/escname.out_lint
@@ -1,4 +1,5 @@
 mandoc: escname.in:9:5: ERROR: escaped character not allowed in a name: first\e
-mandoc: escname.in:12:5: ERROR: escaped character not allowed in a name: first\e
-mandoc: escname.in:18:13: WARNING: invalid escape sequence: \n[second
-mandoc: escname.in:18:12: STYLE: whitespace at end of input line
+mandoc: escname.in:11:10: WARNING: undefined escape, printing literally: \G
+mandoc: escname.in:14:5: ERROR: escaped character not allowed in a name: first\e
+mandoc: escname.in:20:13: WARNING: invalid escape sequence: \n[second
+mandoc: escname.in:20:12: STYLE: whitespace at end of input line

diff --git a/regress/usr.bin/mandoc/roff/string/Makefile b/regress/usr.bin/mandoc/roff/string/Makefile
index 32f192a..2fa1055 100644 (file)
--- a/regress/usr.bin/mandoc/roff/string/Makefile
+++ b/regress/usr.bin/mandoc/roff/string/Makefile
@@ -1,4 +1,9 @@
-# $OpenBSD: Makefile,v 1.9 2018/08/16 13:49:40 schwarze Exp $
+# $OpenBSD: Makefile,v 1.10 2022/06/03 11:50:25 schwarze Exp $
+#
+# This directory is intended for tests of string *expansion*,
+# in particular testing the behaviour of the \* escape sequence.
+# Tests of string *definitions* are better placed in the roff/ds
+# directory.
 
 REGRESS_TARGETS         = dotT escape infinite name std undef zerolength
 LINT_TARGETS    = name std undef

diff --git a/regress/usr.bin/mandoc/roff/string/name.in b/regress/usr.bin/mandoc/roff/string/name.in
index 2948f16..b2612be 100644 (file)
--- a/regress/usr.bin/mandoc/roff/string/name.in
+++ b/regress/usr.bin/mandoc/roff/string/name.in
@@ -1,5 +1,5 @@
-.\" $OpenBSD: name.in,v 1.4 2017/07/04 14:53:27 schwarze Exp $
-.Dd $Mdocdate: July 4 2017 $
+.\" $OpenBSD: name.in,v 1.5 2022/06/03 11:50:25 schwarze Exp $
+.Dd $Mdocdate: June 3 2022 $
 .Dt STRING-NAME 1
 .Os
 .Sh NAME
@@ -10,7 +10,9 @@
 .ds "quot" value of "quot"
 .ds bs\e value of bs\ee
 .ds bs\\e value of bs\e\ee
+.ds dot. value of dot.
 .ds bl\ e value of bl\e e
+.ds inval\\G value of inval\eG
 norm: \*[norm]
 .br
 norm without closing brace: \*[norm
@@ -26,6 +28,10 @@ bs\e\ee: \*[bs\\e]
 bse: \*[bse]
 .br
 bs: \*[bs]
+.br
+dot.: \*[dot.]
+.br
+dot\e.: \*[dot\.]
 .\".br
 .\"bl\e e: \*[bl\ e]
 .br
@@ -34,3 +40,7 @@ bl e: \*[bl e]
 ble: \*[ble]
 .br
 bl: \*[bl]
+.br
+inval\e\eG: \*[inval\\G]
+.br
+inval\eG: \*[inval\G]

diff --git a/regress/usr.bin/mandoc/roff/string/name.out_ascii b/regress/usr.bin/mandoc/roff/string/name.out_ascii
index 325e28a..38258a7 100644 (file)
--- a/regress/usr.bin/mandoc/roff/string/name.out_ascii
+++ b/regress/usr.bin/mandoc/roff/string/name.out_ascii
@@ -11,8 +11,12 @@ D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
      bs\\e: value of bs\\e
      bse:
      bs:
+     dot.: value of dot.
+     dot\.: value of dot.
      bl e:
      ble:
      bl:
+     inval\\G: value of inval\G
+     inval\G: value of inval\G
 
-OpenBSD                          July 4, 2017                          OpenBSD
+OpenBSD                          June 3, 2022                          OpenBSD

diff --git a/regress/usr.bin/mandoc/roff/string/name.out_lint b/regress/usr.bin/mandoc/roff/string/name.out_lint
index 5a6340a..13283f5 100644 (file)
--- a/regress/usr.bin/mandoc/roff/string/name.out_lint
+++ b/regress/usr.bin/mandoc/roff/string/name.out_lint
@@ -1,16 +1,17 @@
 mandoc: name.in:11:5: ERROR: escaped character not allowed in a name: bs\e
-mandoc: name.in:13:5: ERROR: escaped character not allowed in a name: bl\ 
-mandoc: name.in:16:29: WARNING: invalid escape sequence: \*[norm
-mandoc: name.in:16:28: STYLE: whitespace at end of input line
-mandoc: name.in:18:7: WARNING: undefined string, using "": quot
-mandoc: name.in:18:6: STYLE: whitespace at end of input line
-mandoc: name.in:26:6: WARNING: undefined string, using "": bse
-mandoc: name.in:26:5: STYLE: whitespace at end of input line
-mandoc: name.in:28:5: WARNING: undefined string, using "": bs
-mandoc: name.in:28:4: STYLE: whitespace at end of input line
-mandoc: name.in:32:7: WARNING: undefined string, using "": bl e
-mandoc: name.in:32:6: STYLE: whitespace at end of input line
-mandoc: name.in:34:6: WARNING: undefined string, using "": ble
-mandoc: name.in:34:5: STYLE: whitespace at end of input line
-mandoc: name.in:36:5: WARNING: undefined string, using "": bl
-mandoc: name.in:36:4: STYLE: whitespace at end of input line
+mandoc: name.in:14:5: ERROR: escaped character not allowed in a name: bl\ 
+mandoc: name.in:18:29: WARNING: invalid escape sequence: \*[norm
+mandoc: name.in:18:28: STYLE: whitespace at end of input line
+mandoc: name.in:20:7: WARNING: undefined string, using "": quot
+mandoc: name.in:20:6: STYLE: whitespace at end of input line
+mandoc: name.in:28:6: WARNING: undefined string, using "": bse
+mandoc: name.in:28:5: STYLE: whitespace at end of input line
+mandoc: name.in:30:5: WARNING: undefined string, using "": bs
+mandoc: name.in:30:4: STYLE: whitespace at end of input line
+mandoc: name.in:38:7: WARNING: undefined string, using "": bl e
+mandoc: name.in:38:6: STYLE: whitespace at end of input line
+mandoc: name.in:40:6: WARNING: undefined string, using "": ble
+mandoc: name.in:40:5: STYLE: whitespace at end of input line
+mandoc: name.in:42:5: WARNING: undefined string, using "": bl
+mandoc: name.in:42:4: STYLE: whitespace at end of input line
+mandoc: name.in:46:19: WARNING: undefined escape, printing literally: \G

diff --git a/usr.bin/mandoc/roff.c b/usr.bin/mandoc/roff.c
index 724c345..0301b83 100644 (file)
--- a/usr.bin/mandoc/roff.c
+++ b/usr.bin/mandoc/roff.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: roff.c,v 1.264 2022/06/02 11:28:16 schwarze Exp $ */
+/* $OpenBSD: roff.c,v 1.265 2022/06/03 11:50:25 schwarze Exp $ */
 /*
  * Copyright (c) 2010-2015, 2017-2022 Ingo Schwarze <schwarze@openbsd.org>
  * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
@@ -1373,6 +1373,7 @@ roff_expand(struct roff *r, struct buf *buf, int ln, int pos, char ec)
        int              iarg;          /* index beginning the argument */
        int              iendarg;       /* index right after the argument */
        int              iend;          /* index right after the sequence */
+       int              isrc, idst;    /* to reduce \\ and \. in names */
        int              deftype;       /* type of definition to paste */
        int              argi;          /* macro argument index */
        int              quote_args;    /* true for \\$@, false for \\$* */
@@ -1426,6 +1427,21 @@ roff_expand(struct roff *r, struct buf *buf, int ln, int pos, char ec)
                        continue;
                }
 
+               /* Reduce \\ and \. in names. */
+
+               if (buf->buf[inam] == '*' || buf->buf[inam] == 'n') {
+                       isrc = idst = iarg;
+                       while (isrc < iendarg) {
+                               if (isrc + 1 < iendarg &&
+                                   buf->buf[isrc] == '\\' &&
+                                   (buf->buf[isrc + 1] == '\\' ||
+                                    buf->buf[isrc + 1] == '.'))
+                                       isrc++;
+                               buf->buf[idst++] = buf->buf[isrc++];
+                       }
+                       iendarg -= isrc - idst;
+               }
+
                /* Handle expansion. */
 
                res = NULL;
@@ -4000,7 +4016,7 @@ static size_t
 roff_getname(struct roff *r, char **cpp, int ln, int pos)
 {
        char     *name, *cp;
-       size_t    namesz;
+       int       namesz, inam, iend;
 
        name = *cpp;
        if (*name == '\0')
@@ -4008,24 +4024,46 @@ roff_getname(struct roff *r, char **cpp, int ln, int pos)
 
        /* Advance cp to the byte after the end of the name. */
 
-       for (cp = name; 1; cp++) {
-               namesz = cp - name;
+       cp = name;
+       namesz = 0;
+       for (;;) {
                if (*cp == '\0')
                        break;
                if (*cp == ' ' || *cp == '\t') {
                        cp++;
                        break;
                }
-               if (*cp != '\\')
+               if (*cp != '\\') {
+                       if (name + namesz < cp) {
+                               name[namesz] = *cp;
+                               *cp = ' ';
+                       }
+                       namesz++;
+                       cp++;
                        continue;
+               }
                if (cp[1] == '{' || cp[1] == '}')
                        break;
-               if (*++cp == '\\')
-                       continue;
-               mandoc_msg(MANDOCERR_NAMESC, ln, pos,
-                   "%.*s", (int)(cp - name + 1), name);
-               mandoc_escape((const char **)&cp, NULL, NULL);
-               break;
+               if (roff_escape(cp, 0, 0, NULL, &inam,
+                   NULL, NULL, &iend) != ESCAPE_UNDEF) {
+                       mandoc_msg(MANDOCERR_NAMESC, ln, pos,
+                           "%.*s%.*s", namesz, name, iend, cp);
+                       cp += iend;
+                       break;
+               }
+
+               /*
+                * In an identifier, \\, \., \G and so on
+                * are reduced to \, ., G and so on,
+                * vaguely similar to copy mode.
+                */
+
+               name[namesz++] = cp[inam];
+               while (iend--) {
+                       if (cp >= name + namesz)
+                               *cp = ' ';
+                       cp++;
+               }
        }
 
        /* Read past spaces. */