re PR c++/24985 (caret diagnostics)

2012-04-11  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR 24985
gcc/
        * diagnostic.h (show_caret): Declare.
	(caret_max_width): Declare.
	(diagnostic_show_locus): Declare.
        * diagnostic.c (diagnostic_initialize): Initialize to false.
        (diagnostic_show_locus): New.
        (diagnostic_report_diagnostic): Call it.
	(getenv_columns): New.
	(adjust_line): New.
	(diagnostic_set_caret_max_width): New.
        * input.c (read_line): New.
	(location_get_source_line): New.
        * input.h (location_get_source_line): Declare.
        * toplev.c (general_init): Initialize show_caret from options.
        * dwarf2out.c (gen_producer_string): Handle fdiagnostics-show-caret.
        * opts.c (common_handle_option): Likewise.
	* pretty-print.h (pp_get_prefix): New.
	(pp_base_get_prefix): New.
        * common.opt (fdiagnostics-show-caret): New option.
	* doc/invoke.texi (fdiagnostics-show-caret): Document it.
testsuite/
        * lib/prune.exp: Add -fno-diagnostics-show-caret.
libstdc++-v3/
	* testsuite/lib/prune.exp: Handle caret.
libmudflap/
	* testsuite/lib/libmudflap.exp: Handle caret.

From-SVN: r186305

1 files changed, 98 insertions, 0 deletions

diff --git a/gcc/diagnostic.c b/gcc/diagnostic.c
index a68d6ce..60773d3 100644
--- a/gcc/diagnostic.c
+++ b/gcc/diagnostic.c
@@ -78,6 +78,35 @@ file_name_as_prefix (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.  */
+static int
+getenv_columns (void)
+{
+  const char * s = getenv ("COLUMNS");
+  if (s != NULL) {
+    int n = atoi (s);
+    if (n > 0)
+      return n;
+  }
+  return INT_MAX;
+}
+
+/* Set caret_max_width to value.  */
+void
+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 (context->printer->buffer->stream))
+       ? getenv_columns () - 1: INT_MAX);
+  
+  if (value <= 0) 
+    value = INT_MAX;
+
+  context->caret_max_width = value;
+}
+
 /* Initialize the diagnostic message outputting machinery.  */
 void
 diagnostic_initialize (diagnostic_context *context, int n_opts)
@@ -100,6 +129,8 @@ diagnostic_initialize (diagnostic_context *context, int n_opts)
   context->classify_diagnostic = XNEWVEC (diagnostic_t, n_opts);
   for (i = 0; i < n_opts; i++)
     context->classify_diagnostic[i] = DK_UNSPECIFIED;
+  context->show_caret = false;
+  diagnostic_set_caret_max_width (context, pp_line_cutoff (context->printer));
   context->show_option_requested = false;
   context->abort_on_error = false;
   context->show_column = false;
@@ -196,6 +227,72 @@ diagnostic_build_prefix (diagnostic_context *context,
      : build_message_string ("%s:%d: %s", s.file, s.line, text));
 }
 
+/* If LINE is longer than MAX_WIDTH, and COLUMN is not smaller than
+   MAX_WIDTH by some margin, then adjust the start of the line such
+   that the COLUMN is smaller than MAX_WIDTH minus the margin.  The
+   margin is either 10 characters or the difference between the column
+   and the length of the line, whatever is smaller.  */
+static const char *
+adjust_line (const char *line, int max_width, int *column_p)
+{
+  int right_margin = 10;
+  int line_width = strlen (line);
+  int column = *column_p;
+
+  right_margin = MIN(line_width - column, right_margin);
+  right_margin = max_width - right_margin;
+  if (line_width >= max_width && column > right_margin)
+    {
+      line += column - right_margin;
+      *column_p = right_margin;
+    }
+  return line;
+}
+
+/* Print the physical source line corresponding to the location of
+   this diagnostics, and a caret indicating the precise column.  */
+void
+diagnostic_show_locus (diagnostic_context * context,
+		       const diagnostic_info *diagnostic)
+{
+  const char *line;
+  char *buffer;
+  expanded_location s;
+  int max_width;
+  const char *saved_prefix;
+
+
+  if (!context->show_caret
+      || diagnostic->location <= BUILTINS_LOCATION)
+    return;
+
+  s = expand_location(diagnostic->location);
+  line = location_get_source_line (s);
+  if (line == NULL)
+    return;
+
+  max_width = context->caret_max_width;
+  line = adjust_line (line, max_width, &(s.column));
+
+  pp_newline (context->printer);
+  saved_prefix = pp_get_prefix (context->printer);
+  pp_set_prefix (context->printer, NULL);
+  pp_character (context->printer, ' ');
+  while (max_width > 0 && *line != '\0')
+    {
+      char c = *line == '\t' ? ' ' : *line;
+      pp_character (context->printer, c);
+      max_width--;
+      line++;
+    }
+  pp_newline (context->printer);
+  /* pp_printf does not implement %*c.  */
+  buffer = XALLOCAVEC (char, s.column + 3);
+  snprintf (buffer, s.column + 3, " %*c", s.column, '^');
+  pp_string (context->printer, buffer);
+  pp_set_prefix (context->printer, saved_prefix);
+}
+
 /* Take any action which is expected to happen after the diagnostic
    is written out.  This function does not always return.  */
 static void
@@ -547,6 +644,7 @@ diagnostic_report_diagnostic (diagnostic_context *context,
   pp_format (context->printer, &diagnostic->message);
   (*diagnostic_starter (context)) (context, diagnostic);
   pp_output_formatted_text (context->printer);
+  diagnostic_show_locus (context, diagnostic);
   (*diagnostic_finalizer (context)) (context, diagnostic);
   pp_flush (context->printer);
   diagnostic_action_after_output (context, diagnostic);