[groff] 04/10: [troff]: Handle invalid `-o` argument better.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit 913dcac60e0fcfe11644c70fce61292ad4147807
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Thu Oct 17 10:28:27 2024 -0500

    [troff]: Handle invalid `-o` argument better.
    
    * src/roff/troff/input.cpp (parse_output_page_list): Enhance diagnostic
      message when `-o` option argument is nonsense; report the invalid
      expression and inform user that it's being ignored.
    
    Exhibit:
    $ echo hello | ./build/test-groff -z -o 99x
    troff: error: ignoring invalid output page list argument '99x'
---
 ChangeLog                | 6 ++++++
 src/roff/troff/input.cpp | 5 +++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 51311f5f9..a80ec8925 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2024-10-17  G. Branden Robinson <g.branden.robinson@gmail.com>
+
+       * src/roff/troff/input.cpp (parse_output_page_list): Enhance
+       diagnostic message when `-o` option argument is nonsense; report
+       the invalid expression and inform user that it's being ignored.
+
 2024-10-17  G. Branden Robinson <g.branden.robinson@gmail.com>
 
        * src/roff/troff/input.cpp (in_output_page_list): Demote return
diff --git a/src/roff/troff/input.cpp b/src/roff/troff/input.cpp
index 48e2707f7..b5d616ea3 100644
--- a/src/roff/troff/input.cpp
+++ b/src/roff/troff/input.cpp
@@ -8598,6 +8598,7 @@ bool in_output_page_list(int n)
 
 static void parse_output_page_list(const char *p)
 {
+  const char *pstart = p; // for diagnostic message
   for (;;) {
     int i;
     if (*p == '-')
@@ -8632,8 +8633,8 @@ static void parse_output_page_list(const char *p)
     ++p;
   }
   if (*p != '\0') {
-    error("bad output page list");
-    output_page_list = 0;
+    error("ignoring invalid output page list argument '%1'", pstart);
+    output_page_list = 0 /* nullptr */;
   }
 }