gbranden pushed a commit to branch master
in repository groff.
commit a9e4729cf72a758387c1f41e73a3f6bb955b1832
Author: G. Branden Robinson <[email protected]>
AuthorDate: Mon Oct 20 14:14:48 2025 -0500
[troff]: Throw syntax warning on chars after `\c`.
* src/roff/troff/env.cpp (environment::add_char): Throw syntax warning
upon encountering formattable ordinary or special characters after
`\c` escape sequence on an input line.
* src/roff/troff/troff.1.man (Warnings): Document it.
Illustration:
$ printf 'foo\\cbar\n' | ./build/test-groff -z
troff:<standard input>:1: warning: ignoring character 'b' on input line
after output line continuation escape sequence
troff:<standard input>:1: warning: ignoring character 'a' on input line
after output line continuation escape sequence
troff:<standard input>:1: warning: ignoring character 'r' on input line
after output line continuation escape sequence
$ printf 'foo\\c\\[aq]\n' | ./build/test-groff -z
troff:<standard input>:1: warning: ignoring special character on input line
after output line continuation escape sequence
$ printf 'foo\\c!"#$%%&'"'"'\n' | ./build/test-groff -z
troff:<standard input>:1: warning: ignoring character '!' on input line
after output line continuation escape sequence
troff:<standard input>:1: warning: ignoring character '"' on input line
after output line continuation escape sequence
troff:<standard input>:1: warning: ignoring character '#' on input line
after output line continuation escape sequence
troff:<standard input>:1: warning: ignoring character '$' on input line
after output line continuation escape sequence
troff:<standard input>:1: warning: ignoring character '%' on input line
after output line continuation escape sequence
troff:<standard input>:1: warning: ignoring character '&' on input line
after output line continuation escape sequence
troff:<standard input>:1: warning: ignoring character "'" on input line
after output line continuation escape sequence
---
ChangeLog | 7 +++++++
src/roff/troff/env.cpp | 14 ++++++++++++--
src/roff/troff/troff.1.man | 2 ++
3 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 42a19c145..412881ccd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2025-10-20 G. Branden Robinson <[email protected]>
+
+ * src/roff/troff/env.cpp (environment::add_char): Throw syntax
+ warning upon encountering formattable ordinary or special
+ characters after `\c` escape sequence on an input line.
+ * src/roff/troff/troff.1.man (Warnings): Document it.
+
2025-10-20 G. Branden Robinson <[email protected]>
* tmac/an.tmac (an*end-hyperlink): Work around apparently
diff --git a/src/roff/troff/env.cpp b/src/roff/troff/env.cpp
index 566baf446..73408f956 100644
--- a/src/roff/troff/env.cpp
+++ b/src/roff/troff/env.cpp
@@ -343,8 +343,18 @@ void leader_character_request()
void environment::add_char(charinfo *ci)
{
node *gc_np = 0 /* nullptr */;
- if (was_line_interrupted)
- ;
+ if (was_line_interrupted) {
+ unsigned char cc = ci->get_ascii_code();
+ if (0 == cc)
+ warning(WARN_SYNTAX, "ignoring special character on input line"
+ " after output line continuation escape sequence");
+ else if (cc != '\'' )
+ warning(WARN_SYNTAX, "ignoring character '%1' on input line after"
+ " output line continuation escape sequence", cc);
+ else
+ warning(WARN_SYNTAX, "ignoring character \"%1\" on input line"
+ " after output line continuation escape sequence", cc);
+ }
// don't allow fields in dummy environments
else if (ci == field_delimiter_char && !is_dummy_env) {
if (has_current_field)
diff --git a/src/roff/troff/troff.1.man b/src/roff/troff/troff.1.man
index ed6cd3029..e1fa1d432 100644
--- a/src/roff/troff/troff.1.man
+++ b/src/roff/troff/troff.1.man
@@ -796,6 +796,8 @@ It never occurs in compatibility mode.
A self-contradictory hyphenation mode or character flags were requested;
an empty or incomplete numeric expression was encountered;
an operand to a numeric operator was missing;
+an attempt was made to format characters on an input line
+after an output line continuation escape sequence;
a recognized but inapposite escape sequence
or unprintable character code
was used in a device extension command;
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