[PATCH] Offer suggestions for misspelled --param names.

[David Malcolm <dmalcolm at redhat dot com>]

Another use of spellcheck.{c|h}, this time for --param.

Successfully bootstrapped&regretested on x86_64-pc-linux-gnu;
adds 4 PASS results to gcc.sum.

OK for trunk?

gcc/ChangeLog:
	* opts.c (handle_param): Use find_param_fuzzy to offer suggestions
	for misspelled param names.
	* params.c: Include spellcheck.h.
	(find_param_fuzzy): New function.
	* params.h (find_param_fuzzy): New prototype.
	* spellcheck.c (struct edit_distance_traits<const char *>): Move
	to...
	* spellcheck.h (struct edit_distance_traits<const char *>):
	...here.

gcc/testsuite/ChangeLog:
	* gcc.dg/spellcheck-params.c: New testcase.
	* gcc.dg/spellcheck-params-2.c: New testcase.
---
 gcc/opts.c                                 |  9 ++++++++-
 gcc/params.c                               | 14 ++++++++++++++
 gcc/params.h                               |  1 +
 gcc/spellcheck.c                           | 18 ------------------
 gcc/spellcheck.h                           | 18 ++++++++++++++++++
 gcc/testsuite/gcc.dg/spellcheck-params-2.c |  4 ++++
 gcc/testsuite/gcc.dg/spellcheck-params.c   |  4 ++++
 7 files changed, 49 insertions(+), 19 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/spellcheck-params-2.c
 create mode 100644 gcc/testsuite/gcc.dg/spellcheck-params.c

diff --git a/gcc/opts.c b/gcc/opts.c
index 7406210..f09c520 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -2228,7 +2228,14 @@ handle_param (struct gcc_options *opts, struct gcc_options *opts_set,
 
       enum compiler_param index;
       if (!find_param (arg, &index))
-	error_at (loc, "invalid --param name %qs", arg);
+	{
+	  const char *suggestion = find_param_fuzzy (arg);
+	  if (suggestion)
+	    error_at (loc, "invalid --param name %qs; did you mean %qs?",
+		      arg, suggestion);
+	  else
+	    error_at (loc, "invalid --param name %qs", arg);
+	}
       else
 	{
 	  if (!param_string_value_p (index, equal + 1, &value))
diff --git a/gcc/params.c b/gcc/params.c
index 41660b4..1b5000b 100644
--- a/gcc/params.c
+++ b/gcc/params.c
@@ -25,6 +25,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "params.h"
 #include "params-enum.h"
 #include "diagnostic-core.h"
+#include "spellcheck.h"
 
 /* An array containing the compiler parameters and their current
    values.  */
@@ -142,6 +143,19 @@ find_param (const char *name, enum compiler_param *index)
   return false;
 }
 
+/* Look for the closest match for NAME in the parameter table, returning it
+   if it is a reasonable suggestion for a misspelling.  Return NULL
+   otherwise.  */
+
+const char *
+find_param_fuzzy (const char *name)
+{
+  best_match <const char *, const char *> bm (name);
+  for (size_t i = 0; i < num_compiler_params; ++i)
+    bm.consider (compiler_params[i].option);
+  return bm.get_best_meaningful_candidate ();
+}
+
 /* Return true if param with entry index INDEX should be defined using strings.
    If so, return the value corresponding to VALUE_NAME in *VALUE_P.  */
 
diff --git a/gcc/params.h b/gcc/params.h
index 7221ab6..97c8d56 100644
--- a/gcc/params.h
+++ b/gcc/params.h
@@ -89,6 +89,7 @@ enum compiler_param
 };
 
 extern bool find_param (const char *, enum compiler_param *);
+extern const char *find_param_fuzzy (const char *name);
 extern bool param_string_value_p (enum compiler_param, const char *, int *);
 
 /* The value of the parameter given by ENUM.  Not an lvalue.  */
diff --git a/gcc/spellcheck.c b/gcc/spellcheck.c
index 2648f3a..b37b1e4 100644
--- a/gcc/spellcheck.c
+++ b/gcc/spellcheck.c
@@ -121,24 +121,6 @@ levenshtein_distance (const char *s, const char *t)
   return levenshtein_distance (s, strlen (s), t, strlen (t));
 }
 
-/* Specialization of edit_distance_traits for C-style strings.  */
-
-template <>
-struct edit_distance_traits<const char *>
-{
-  static size_t get_length (const char *str)
-  {
-    gcc_assert (str);
-    return strlen (str);
-  }
-
-  static const char *get_string (const char *str)
-  {
-    gcc_assert (str);
-    return str;
-  }
-};
-
 /* Given TARGET, a non-NULL string, and CANDIDATES, a non-NULL ptr to
    an autovec of non-NULL strings, determine which element within
    CANDIDATES has the lowest edit distance to TARGET.  If there are
diff --git a/gcc/spellcheck.h b/gcc/spellcheck.h
index 035f4ac..b48cfbc 100644
--- a/gcc/spellcheck.h
+++ b/gcc/spellcheck.h
@@ -48,6 +48,24 @@ find_closest_string (const char *target,
 template <typename TYPE>
 struct edit_distance_traits {};
 
+/* Specialization of edit_distance_traits for C-style strings.  */
+
+template <>
+struct edit_distance_traits<const char *>
+{
+  static size_t get_length (const char *str)
+  {
+    gcc_assert (str);
+    return strlen (str);
+  }
+
+  static const char *get_string (const char *str)
+  {
+    gcc_assert (str);
+    return str;
+  }
+};
+
 /* A type for use when determining the best match against a string,
    expressed as a template so that we can match against various
    string-like types (const char *, frontend identifiers, and preprocessor
diff --git a/gcc/testsuite/gcc.dg/spellcheck-params-2.c b/gcc/testsuite/gcc.dg/spellcheck-params-2.c
new file mode 100644
index 0000000..27e293f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/spellcheck-params-2.c
@@ -0,0 +1,4 @@
+/* { dg-do compile } */
+/* { dg-options "--param does-not-resemble-anything=42" } */
+/* { dg-error "invalid --param name .does-not-resemble-anything."  "" { target *-*-* } 0 } */
+
diff --git a/gcc/testsuite/gcc.dg/spellcheck-params.c b/gcc/testsuite/gcc.dg/spellcheck-params.c
new file mode 100644
index 0000000..1bb7bca
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/spellcheck-params.c
@@ -0,0 +1,4 @@
+/* { dg-do compile } */
+/* { dg-options "--param max-early-inliner-iteration=3" } */
+/* { dg-error "invalid --param name .max-early-inliner-iteration.; did you mean .max-early-inliner-iterations.?"  "" { target *-*-* } 0 } */
+
-- 
1.8.5.3