This patch fixes a Fortran diagnostic "regression".
With the current common diagnostic, the width shown with caret
diagnostic is determined by:
case OPT_fmessage_length_:
pp_set_line_maximum_length (dc->printer, value);
diagnostic_set_caret_max_width (dc, value);
plus
diagnostic_set_caret_max_width (diagnostic_context *context, int value)
{
/* One minus to account for the leading empty space. */
value = value ? value - 1
: (isatty (fileno (pp_buffer (context->printer)->stream))
? getenv_columns () - 1: INT_MAX);
if (value <= 0)
value = INT_MAX;
context->caret_max_width = value;
}
where getenv_columns looks at the environment variable COLUMNS.
Note that -fmessage-length= applies to the error message (wraps) _and_
the caret diagnostic (truncates) while the COLUMNS variable _only_
applies to the caret diagnostic. (BTW: The documentation currently does
not mention COLUMNS.)
On most terminals, which I tried, COLUMNS does not seem to be set. In
Fortran, error.c's get_terminal_width has a similar check, but
additionally it uses ioctl to determine the terminal width.
I think with caret diagnostics, it is useful not to exceed the terminal
width as having several "empty" lines before the "^" does not really
improve the readability. Thus, I would propose to additionally use
ioctl. Which rises two questions: (a) Should the COLUMNS environment
variable or ioctl have a higher priority? [Fortran ranks ioctl higher;
in the patch, for backward compatibilty, I rank COLUMNS higher.] (b)
Should ioctl be always used or only for Fortran?
Comments?
Tobias
diff --git a/gcc/diagnostic.c b/gcc/diagnostic.c
index 28ef81c..9a29300 100644
--- a/gcc/diagnostic.c
+++ b/gcc/diagnostic.c
@@ -82,18 +82,27 @@ file_name_as_prefix (diagnostic_context *context, const char *f)
/* Return the value of the getenv("COLUMNS") as an integer. If the
- value is not set to a positive integer, then return INT_MAX. */
+ value is not set to a positive integer, use ioctl to get the
+ terminal width. If it fails, return INT_MAX. */
static int
-getenv_columns (void)
+getenv_columns_and_termwidth (void)
{
const char * s = getenv ("COLUMNS");
if (s != NULL) {
int n = atoi (s);
if (n > 0)
return n;
}
+
+#ifdef TIOCGWINSZ
+ struct winsize w;
+ w.ws_col = 0;
+ if (ioctl (0, TIOCGWINSZ, &w) == 0 && w.ws_col > 0)
+ return w.ws_col;
+#endif
+
return INT_MAX;
}
/* Set caret_max_width to value. */
@@ -102,9 +111,9 @@ diagnostic_set_caret_max_width (diagnostic_context *context, int value)
{
/* One minus to account for the leading empty space. */
value = value ? value - 1
: (isatty (fileno (pp_buffer (context->printer)->stream))
- ? getenv_columns () - 1: INT_MAX);
+ ? getenv_columns_and_termwidth () - 1: INT_MAX);
if (value <= 0)
value = INT_MAX;