all: quote string arguments in error messages

These strings are often file names or other user specified
parameters, which can give confusing errors in
the presence of unexpected characters for example.

* cfg.mk (sc_error_quotes): A new syntax check rule.
* src/*.c: Wrap error() string arguments with quote().
* tests/: Adjust accordingly.
* NEWS: Mention the improvement.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/fmt.c b/src/fmt.c
index b12c9b9ed..f37f7cd88 100644
--- a/src/fmt.c
+++ b/src/fmt.c
@@ -431,7 +431,7 @@ main (int argc, char **argv)
                   fmt (in_stream);
                   if (fclose (in_stream) == EOF)
                     {
-                      error (0, errno, "%s", file);
+                      error (0, errno, "%s", quote (file));
                       ok = false;
                     }
                 }