Support fix-it hints that add new lines

Previously fix-it hints couldn't contain newlines.  This is
due to the need to print something user-readable for them
within diagnostic-show-locus, and for handling them within
edit-context for printing diffs and regenerating content.

This patch enables limited support for fix-it hints with newlines,
for suggesting adding new lines.
Such a fix-it hint must have exactly one newline character, at the
end of the content.  It must be an insertion at the beginning of
a line (so that e.g. fix-its that split a pre-existing line are
still rejected).

They are printed by diagnostic-show-locus with a '+' in the
left-hand margin, like this:

test.c:42:4: note: suggest adding 'break;' here
+      break;
     case 'b':
     ^~~~~~~~~

and the printer injects "spans" if the insertion location is not
near the primary range of the diagnostic e.g.:

test.c:4:2: note: unrecognized 'putchar'; suggest including '<stdio.h>'
test.c:1:1:
+#include <stdio.h>

test.c:4:2:
  putchar (ch);
  ^~~~~~~

gcc/ChangeLog:
	* diagnostic-show-locus.c
	(layout::should_print_annotation_line_p): Make private.
	(layout::print_annotation_line): Make private.
	(layout::annotation_line_showed_range_p): Make private.
	(layout::show_ruler): Make private.
	(layout::print_source_line): Make private.  Pass in line and
	line_width, rather than calling location_get_source_line.  Drop
	returned value.
	(layout::print_leading_fixits): New method.
	(layout::print_any_fixits): Rename to...
	(layout::print_trailing_fixits): ...this, and make private.
	Don't print newline fixits.
	(diagnostic_show_locus): Move logic for printing one row into...
	(layout::print_line): ...this new function.  Move the
	location_get_source_line call and error-handling from
	print_source_line to here.  Call print_leading_fixits, and rename
	print_any_fixits to print_trailing_fixits.
	(selftest::test_fixit_insert_containing_newline): Update now that
	newlines are partially supported.
	(selftest::test_fixit_insert_containing_newline_2): New test.
	(selftest::test_fixit_replace_containing_newline): Update comments.
	(selftest::diagnostic_show_locus_c_tests): Call the new test.
	* edit-context.c (class added_line): New class.
	(class edited_line): Describe newline handling in comment.
	(edited_line::actually_edited_p): New method.
	(edited_line::print_content): Delete redundant decl.
	(edited_line::m_predecessors): New field.
	(edited_file::print_content): Call edited_line::print_content.
	(edited_file::print_diff): Update to support newlines.
	(edited_file::print_diff_hunk): Likewise.
	(edited_file::print_run_of_changed_lines): New function.
	(edited_file::print_diff_line): Convert to...
	(print_diff_line): ...this.
	(edited_file::get_effective_line_count): New function.
	(edited_line::edited_line): Initialize new field m_predecessors.
	(edited_line::~edited_line): Clean up m_predecessors.
	(edited_line::apply_fixit): Handle newlines.
	(edited_line::get_effective_line_count): New function.
	(edited_line::print_content): New function.
	(edited_line::print_diff_lines): New function.
	(selftest::test_applying_fixits_insert_containing_newline): New
	test.
	(selftest::test_applying_fixits_replace_containing_newline): New
	test.
	(selftest::insert_line): New function.
	(selftest::test_applying_fixits_multiple_lines): Add example of
	inserting a line.
	(selftest::edit_context_c_tests): Call the new tests.

gcc/testsuite/ChangeLog:
	* gcc.dg/plugin/diagnostic-test-show-locus-bw.c
	(test_fixit_insert_newline): New function.
	* gcc.dg/plugin/diagnostic-test-show-locus-color.c
	(test_fixit_insert_newline): New function.
	* gcc.dg/plugin/diagnostic-test-show-locus-generate-patch.c
	(test_fixit_insert_newline): New function.
	* gcc.dg/plugin/diagnostic-test-show-locus-parseable-fixits.c
	(test_fixit_insert_newline): New function.
	* gcc.dg/plugin/diagnostic_plugin_test_show_locus.c
	(test_show_locus): Handle test_fixit_insert_newline.

libcpp/ChangeLog:
	* include/line-map.h (class rich_location): Update description of
	newline handling.
	(class fixit_hint): Likewise.
	(fixit_hint::ends_with_newline_p): New decl.
	* line-map.c (rich_location::maybe_add_fixit): Support newlines
	in fix-it hints that are insertions of single lines at the start
	of a line.  Don't consolidate into such fix-it hints.
	(fixit_hint::ends_with_newline_p): New method.

From-SVN: r247522

6 files changed, 102 insertions, 0 deletions

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 4a7c4e4..33a5cde 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,16 @@
+2017-05-02  David Malcolm  <dmalcolm@redhat.com>
+
+	* gcc.dg/plugin/diagnostic-test-show-locus-bw.c
+	(test_fixit_insert_newline): New function.
+	* gcc.dg/plugin/diagnostic-test-show-locus-color.c
+	(test_fixit_insert_newline): New function.
+	* gcc.dg/plugin/diagnostic-test-show-locus-generate-patch.c
+	(test_fixit_insert_newline): New function.
+	* gcc.dg/plugin/diagnostic-test-show-locus-parseable-fixits.c
+	(test_fixit_insert_newline): New function.
+	* gcc.dg/plugin/diagnostic_plugin_test_show_locus.c
+	(test_show_locus): Handle test_fixit_insert_newline.
+
 2017-05-02  Bin Cheng  <bin.cheng@arm.com>
 
 	* g++.dg/tree-ssa/ivopts-3.C: Adjust test string.
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 e8112bf..25b9d6c 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
@@ -249,3 +249,23 @@ void test_many_nested_locations (void)
      MOLLIT ANIM ID EST LABORUM
    { dg-end-multiline-output "" } */
 }
+
+/* Unit test for rendering of fix-it hints that add new lines.  */
+
+void test_fixit_insert_newline (void)
+{
+#if 0
+  switch (op)
+    {
+    case 'a':
+      x = a;
+    case 'b':  /* { dg-warning "newline insertion" } */
+      x = b;
+    }
+/* { dg-begin-multiline-output "" }
++      break;
+     case 'b':
+     ^~~~~~~~
+   { dg-end-multiline-output "" } */
+#endif
+}
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 712375e..3fb1c24 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
@@ -193,3 +193,23 @@ void test_fixit_replace (void)
    { dg-end-multiline-output "" } */
 #endif
 }
+
+/* Unit test for rendering of fix-it hints that add new lines.  */
+
+void test_fixit_insert_newline (void)
+{
+#if 0
+  switch (op)
+    {
+    case 'a':
+      x = a;
+    case 'b':  /* { dg-warning "newline insertion" } */
+      x = b;
+    }
+/* { dg-begin-multiline-output "" }
++      break;
+     case 'b':
+     ^~~~~~~~
+   { dg-end-multiline-output "" } */
+#endif
+}
diff --git a/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-generate-patch.c b/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-generate-patch.c
index afbaf63..4522dcd 100644
--- a/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-generate-patch.c
+++ b/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-generate-patch.c
@@ -36,7 +36,20 @@ void test_fixit_replace (void)
 #endif
 }
 
+/* Unit test for rendering of fix-it hints that add new lines.  */
 
+void test_fixit_insert_newline (void)
+{
+#if 0
+  switch (op)
+    {
+    case 'a':
+      x = a;
+    case 'b': /* { dg-warning "newline insertion" } */
+      x = b;
+    }
+#endif
+}
 
 /* Verify the output from -fdiagnostics-generate-patch.
    We expect a header, containing the filename.  This is the absolute path,
@@ -74,4 +87,12 @@ void test_fixit_replace (void)
  #endif
  }
  
+@@ -45,6 +45,7 @@
+     {
+     case 'a':
+       x = a;
++      break;
+     case 'b':
+       x = b;
+     }
    { dg-end-multiline-output "" } */
diff --git a/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-parseable-fixits.c b/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-parseable-fixits.c
index 1490c98..25a7c3c 100644
--- a/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-parseable-fixits.c
+++ b/gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-parseable-fixits.c
@@ -39,3 +39,19 @@ void test_fixit_replace (void)
 /* { dg-regexp "fix-it:.*\\{38:3-38:21\\}:.*" } */
 #endif
 }
+
+/* Unit test for rendering of fix-it hints that add new lines.  */
+
+void test_fixit_insert_newline (void)
+{
+#if 0
+  switch (op)
+    {
+    case 'a':
+      x = a;
+    case 'b': /* { dg-warning "newline insertion" } */
+      x = b;
+    }
+/* { dg-regexp "fix-it:.*\\{52:1-52:1\\}:.*\\n" } */
+#endif
+}
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 3efc7df..6afb584 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
@@ -268,6 +268,18 @@ test_show_locus (function *fun)
       warning_at_rich_loc (&richloc, 0, "example of insertion hints");
     }
 
+  if (0 == strcmp (fnname, "test_fixit_insert_newline"))
+    {
+      const int line = fnstart_line + 6;
+      location_t line_start = get_loc (line, 0);
+      location_t case_start = get_loc (line, 4);
+      location_t case_finish = get_loc (line, 11);
+      location_t case_loc = make_location (case_start, case_start, case_finish);
+      rich_location richloc (line_table, case_loc);
+      richloc.add_fixit_insert_before (line_start, "      break;\n");
+      warning_at_rich_loc (&richloc, 0, "example of newline insertion hint");
+    }
+
   if (0 == strcmp (fnname, "test_fixit_remove"))
     {
       const int line = fnstart_line + 2;