Spelling suggestions for misspelled preprocessor directives

This patch allows the preprocessor to offer suggestions for misspelled
directives, taking us from e.g.:

test.c:5:2: error: invalid preprocessing directive #endfi
 #endfi
  ^~~~~

to:

test.c:5:2: error: invalid preprocessing directive #endfi; did you mean #endif?
 #endfi
  ^~~~~
  endif

gcc/c-family/ChangeLog:
	* c-common.c: Include "spellcheck.h".
	(cb_get_suggestion): New function.
	* c-common.h (cb_get_suggestion): New decl.
	* c-lex.c (init_c_lex): Initialize cb->get_suggestion to
	cb_get_suggestion.

gcc/testsuite/ChangeLog:
	* gcc.dg/cpp/misspelled-directive-1.c: New testcase.
	* gcc.dg/cpp/misspelled-directive-2.c: New testcase.

libcpp/ChangeLog:
	* directives.c (directive_names): New array.
	(_cpp_handle_directive): Offer spelling suggestions for misspelled
	directives.
	* errors.c (cpp_diagnostic_at_richloc): New function.
	(cpp_error_at_richloc): New function.
	* include/cpplib.h (struct cpp_callbacks): Add field
	"get_suggestion".
	(cpp_error_at_richloc): New decl.

From-SVN: r239585

2 files changed, 33 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.dg/cpp/misspelled-directive-1.c b/gcc/testsuite/gcc.dg/cpp/misspelled-directive-1.c
new file mode 100644
index 0000000..f79670a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/misspelled-directive-1.c
@@ -0,0 +1,12 @@
+#ifndef SOME_GUARD /* { dg-error "unterminated" } */
+
+#if 1
+/* Typo here: "endfi" should have been "endif".  */
+#endfi /* { dg-error "invalid preprocessing directive #endfi; did you mean #endif?" } */
+
+int make_non_empty;
+
+/* Another transposition typo:  */
+#deifne FOO /* { dg-error "invalid preprocessing directive #deifne; did you mean #define?" } */ 
+
+#endif /* #ifndef SOME_GUARD */
diff --git a/gcc/testsuite/gcc.dg/cpp/misspelled-directive-2.c b/gcc/testsuite/gcc.dg/cpp/misspelled-directive-2.c
new file mode 100644
index 0000000..7ec5dee
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/misspelled-directive-2.c
@@ -0,0 +1,21 @@
+/* { dg-options "-fdiagnostics-show-caret" } */
+
+#endfi /* { dg-error "invalid preprocessing directive #endfi; did you mean #endif?" } */
+
+/* Verify that we offer fix-it hints.  */
+/* { dg-begin-multiline-output "" }
+ #endfi
+  ^~~~~
+  endif
+  { dg-end-multiline-output "" } */
+
+/* Test coverage for the case of an unrecognized directive where no suggestion
+   is offered.  */
+
+#this_does_not_match_anything /* { dg-error "invalid preprocessing directive #this_does_not_match_anything" } */
+/* { dg-begin-multiline-output "" }
+ #this_does_not_match_anything
+  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  { dg-end-multiline-output "" } */
+
+int make_non_empty;