[committed] Add debugging ruler to diagnostic-show-locus.c

[David Malcolm <dmalcolm at redhat dot com>]

When debugging diagnostic-show-locus.c, it's invaluable to have a
"ruler" showing column numbers.

This patch adds in support via a new "show_ruler_p" flag within
the diagnostic_context.  There's no direct way for end-users to enable
this, but plugins can enable it by setting the flag, so the
plugin that tests the diagnostic subsystem uses this to verify that
the ruler is correctly printed.

Successfully bootstrapped&regrtested on x86_64-pc-linux-gnu.

Committed to trunk as r236080.

gcc/ChangeLog:
	* diagnostic-show-locus.c (layout::layout): Call show_ruler
	if show_ruler_p was set on the context.
	(layout::show_ruler): New method.
	* diagnostic.h (struct diagnostic_context): Add field
	"show_ruler_p".

gcc/testsuite/ChangeLog:
	* gcc.dg/plugin/diagnostic-test-show-locus-bw.c
	(test_very_wide_line): Add ruler to expected output.
	* gcc.dg/plugin/diagnostic-test-show-locus-color.c
	(test_very_wide_line): Likewise.
	* gcc.dg/plugin/diagnostic_plugin_test_show_locus.c
	(test_show_locus): Within the handling of "test_very_wide_line",
	enable show_ruler_p on the diagnostic context.
---
 gcc/diagnostic-show-locus.c                        | 39 ++++++++++++++++++++++
 gcc/diagnostic.h                                   |  4 +++
 .../gcc.dg/plugin/diagnostic-test-show-locus-bw.c  |  3 ++
 .../plugin/diagnostic-test-show-locus-color.c      |  3 ++
 .../plugin/diagnostic_plugin_test_show_locus.c     |  2 ++
 5 files changed, 51 insertions(+)

diff --git a/gcc/diagnostic-show-locus.c b/gcc/diagnostic-show-locus.c
index bf95666..eeccee5 100644
--- a/gcc/diagnostic-show-locus.c
+++ b/gcc/diagnostic-show-locus.c
@@ -199,6 +199,8 @@ class layout
   void print_annotation_line (int row, const line_bounds lbounds);
   void print_any_fixits (int row, const rich_location *richloc);
 
+  void show_ruler (int max_column) const;
+
  private:
   void calculate_line_spans ();
 
@@ -653,6 +655,9 @@ layout::layout (diagnostic_context * context,
 	m_x_offset = column - right_margin;
       gcc_assert (m_x_offset >= 0);
     }
+
+  if (context->show_ruler_p)
+    show_ruler (m_x_offset + max_width);
 }
 
 /* Return true iff we should print a heading when starting the
@@ -1084,6 +1089,40 @@ layout::move_to_column (int *column, int dest_column)
     }
 }
 
+/* For debugging layout issues, render a ruler giving column numbers
+   (after the 1-column indent).  */
+
+void
+layout::show_ruler (int max_column) const
+{
+  /* Hundreds.  */
+  if (max_column > 99)
+    {
+      pp_space (m_pp);
+      for (int column = 1 + m_x_offset; column <= max_column; column++)
+	if (0 == column % 10)
+	  pp_character (m_pp, '0' + (column / 100) % 10);
+	else
+	  pp_space (m_pp);
+      pp_newline (m_pp);
+    }
+
+  /* Tens.  */
+  pp_space (m_pp);
+  for (int column = 1 + m_x_offset; column <= max_column; column++)
+    if (0 == column % 10)
+      pp_character (m_pp, '0' + (column / 10) % 10);
+    else
+      pp_space (m_pp);
+  pp_newline (m_pp);
+
+  /* Units.  */
+  pp_space (m_pp);
+  for (int column = 1 + m_x_offset; column <= max_column; column++)
+    pp_character (m_pp, '0' + (column % 10));
+  pp_newline (m_pp);
+}
+
 } /* End of anonymous namespace.  */
 
 /* Print the physical source code corresponding to the location of
diff --git a/gcc/diagnostic.h b/gcc/diagnostic.h
index ff57357..48ae50d 100644
--- a/gcc/diagnostic.h
+++ b/gcc/diagnostic.h
@@ -201,6 +201,10 @@ struct diagnostic_context
      source code (to avoid e.g. colorizing just the first character in
      a token, which would look strange).  */
   bool colorize_source_p;
+
+  /* Usable by plugins; if true, print a debugging ruler above the
+     source output.  */
+  bool show_ruler_p;
 };
 
 static inline void
diff --git a/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-bw.c b/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-bw.c
index 8d44078..2748fa1 100644
--- a/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-bw.c
+++ b/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-bw.c
@@ -117,6 +117,9 @@ void test_very_wide_line (void)
 #if 0
                                                                                 float f = foo * bar; /* { dg-warning "95: test" } */
 /* { dg-begin-multiline-output "" }
+     0         0         0         0         0         0         1     
+     4         5         6         7         8         9         0     
+ 6789012345678901234567890123456789012345678901234567890123456789012345
                                               float f = foo * bar;
                                                         ~~~~^~~~~
    { dg-end-multiline-output "" } */
diff --git a/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-color.c b/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-color.c
index a590258..ff2f4d4 100644
--- a/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-color.c
+++ b/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-color.c
@@ -117,6 +117,9 @@ void test_very_wide_line (void)
 #if 0
                                                                                 float f = foo * bar; /* { dg-warning "95: test" } */
 /* { dg-begin-multiline-output "" }
+     0         0         0         0         0         0         1     
+     4         5         6         7         8         9         0     
+ 6789012345678901234567890123456789012345678901234567890123456789012345
                                               float f = foo * bar;
                                                         ~~~~^~~~~
    { dg-end-multiline-output "" } */
diff --git a/gcc/testsuite/gcc.dg/plugin/diagnostic_plugin_test_show_locus.c b/gcc/testsuite/gcc.dg/plugin/diagnostic_plugin_test_show_locus.c
index 95078ce..a5f8f0c 100644
--- a/gcc/testsuite/gcc.dg/plugin/diagnostic_plugin_test_show_locus.c
+++ b/gcc/testsuite/gcc.dg/plugin/diagnostic_plugin_test_show_locus.c
@@ -234,9 +234,11 @@ test_show_locus (function *fun)
   if (0 == strcmp (fnname, "test_very_wide_line"))
     {
       const int line = fnstart_line + 2;
+      global_dc->show_ruler_p = true;
       warning_at (make_location (get_loc (line, 94), get_loc (line, 90),
 				 get_loc (line, 98)),
 		  0, "test");
+      global_dc->show_ruler_p = false;
     }
 
   /* Example of multiple carets.  */
-- 
1.8.5.3