[PATCH v2] C++ FE: handle misspelled identifiers and typenames

[David Malcolm <dmalcolm at redhat dot com>]

Changes in v2:
 - split out the non-C++ parts already approved by Jeff (I've committed
   these as r238522).
 - updated to mirror the fixes for PR c/71858 Jakub made to the
   corresponding C implementation in r238352, skipping anticipated decls
   of builtin functions
 - rewritten to more closely resemble the C FE's implementation

This is a port of the C frontend's r237714 [1] to the C++ frontend:
https://gcc.gnu.org/ml/gcc-patches/2016-06/msg01052.html
offering spelling suggestions for misspelled identifiers, macro names,
and some keywords (e.g. "singed" vs "signed" aka PR c/70339).

Examples of suggestions can be seen in the test case.

Successfully bootstrapped&regrtested on x86_64-pc-linux-gnu; adds
267 PASS results to g++.sum.

OK for trunk?

[1] aka 8469aece13814deddf2cd80538d33c2d0a8d60d9 in the git mirror

gcc/cp/ChangeLog:
	PR c/70339
	PR c/71858
	* name-lookup.c: Include gcc-rich-location.h, spellcheck-tree.h,
	and parser.h.
	(suggest_alternatives_for): If no candidates are found, try
	lookup_name_fuzzy and report if if finds a suggestion.
	(consider_binding_level): New function.
	(lookup_name_fuzzy) New function.
	* parser.c: Include gcc-rich-location.h.
	(cp_lexer_next_token_is_decl_specifier_keyword): Move most of
	logic into...
	(cp_keyword_starts_decl_specifier_p): ...this new function.
	(cp_parser_diagnose_invalid_type_name): When issuing
	"does not name a type" errors, attempt to make a suggestion using
	lookup_name_fuzzy.
	* parser.h (cp_keyword_starts_decl_specifier_p): New prototype.
	* search.c (lookup_field_fuzzy_info::fuzzy_lookup_field): Don't
	attempt to access TYPE_FIELDS within a TYPE_PACK_EXPANSION.

gcc/testsuite/ChangeLog:
	PR c/70339
	PR c/71858
	* g++.dg/spellcheck-identifiers.C: New test case, based on
	gcc.dg/spellcheck-identifiers.c.
	* g++.dg/spellcheck-identifiers-2.C: New test case, based on
	gcc.dg/spellcheck-identifiers-2.c.
	* g++.dg/spellcheck-typenames.C: New test case, based on
	gcc.dg/spellcheck-typenames.c
---
 gcc/cp/name-lookup.c                            | 116 ++++++++++-
 gcc/cp/parser.c                                 |  43 +++-
 gcc/cp/parser.h                                 |   1 +
 gcc/cp/search.c                                 |   4 +
 gcc/testsuite/g++.dg/spellcheck-identifiers-2.C |  43 ++++
 gcc/testsuite/g++.dg/spellcheck-identifiers.C   | 255 ++++++++++++++++++++++++
 gcc/testsuite/g++.dg/spellcheck-typenames.C     |  84 ++++++++
 7 files changed, 533 insertions(+), 13 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/spellcheck-identifiers-2.C
 create mode 100644 gcc/testsuite/g++.dg/spellcheck-identifiers.C
 create mode 100644 gcc/testsuite/g++.dg/spellcheck-typenames.C

diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index cbd5209..561bf71 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -29,6 +29,9 @@ along with GCC; see the file COPYING3.  If not see
 #include "debug.h"
 #include "c-family/c-pragma.h"
 #include "params.h"
+#include "gcc-rich-location.h"
+#include "spellcheck-tree.h"
+#include "parser.h"
 
 /* The bindings for a particular name in a particular scope.  */
 
@@ -4435,9 +4438,20 @@ suggest_alternatives_for (location_t location, tree name)
 
   namespaces_to_search.release ();
 
-  /* Nothing useful to report.  */
+  /* Nothing useful to report for NAME.  Report on likely misspellings,
+     or do nothing.  */
   if (candidates.is_empty ())
-    return;
+    {
+      const char *fuzzy_name = lookup_name_fuzzy (name, FUZZY_LOOKUP_NAME);
+      if (fuzzy_name)
+	{
+	  gcc_rich_location richloc (location);
+	  richloc.add_fixit_misspelled_id (location, fuzzy_name);
+	  inform_at_rich_loc (&richloc, "suggested alternative: %qs",
+			      fuzzy_name);
+	}
+      return;
+    }
 
   inform_n (location, candidates.length (),
 	    "suggested alternative:",
@@ -4672,6 +4686,104 @@ qualified_lookup_using_namespace (tree name, tree scope,
   return result->value != error_mark_node;
 }
 
+/* Helper function for lookup_name_fuzzy.
+   Traverse binding level LVL, looking for good name matches for NAME
+   (and BM).  */
+static void
+consider_binding_level (tree name, best_match <tree, tree> &bm,
+			cp_binding_level *lvl, bool look_within_fields,
+			enum lookup_name_fuzzy_kind kind)
+{
+  if (look_within_fields)
+    if (lvl->this_entity && TREE_CODE (lvl->this_entity) == RECORD_TYPE)
+      {
+	tree type = lvl->this_entity;
+	bool want_type_p = (kind == FUZZY_LOOKUP_TYPENAME);
+	tree best_matching_field
+	  = lookup_member_fuzzy (type, name, want_type_p);
+	if (best_matching_field)
+	  bm.consider (best_matching_field);
+      }
+
+  for (tree t = lvl->names; t; t = TREE_CHAIN (t))
+    {
+      /* Don't use bindings from implicitly declared functions,
+	 as they were likely misspellings themselves.  */
+      if (TREE_TYPE (t) == error_mark_node)
+	continue;
+
+      /* Skip anticipated decls of builtin functions.  */
+      if (TREE_CODE (t) == FUNCTION_DECL)
+	if (DECL_BUILT_IN (t))
+	  if (DECL_ANTICIPATED (t))
+	    continue;
+
+      if (DECL_NAME (t))
+	bm.consider (DECL_NAME (t));
+    }
+}
+
+/* Search for near-matches for NAME within the current bindings, and within
+   macro names, returning the best match as a const char *, or NULL if
+   no reasonable match is found.  */
+
+const char *
+lookup_name_fuzzy (tree name, enum lookup_name_fuzzy_kind kind)
+{
+  gcc_assert (TREE_CODE (name) == IDENTIFIER_NODE);
+
+  best_match <tree, tree> bm (name);
+
+  cp_binding_level *lvl;
+  for (lvl = scope_chain->class_bindings; lvl; lvl = lvl->level_chain)
+    consider_binding_level (name, bm, lvl, true, kind);
+
+  for (lvl = current_binding_level; lvl; lvl = lvl->level_chain)
+    consider_binding_level (name, bm, lvl, false, kind);
+
+  /* Consider macros: if the user misspelled a macro name e.g. "SOME_MACRO"
+     as:
+       x = SOME_OTHER_MACRO (y);
+     then "SOME_OTHER_MACRO" will survive to the frontend and show up
+     as a misspelled identifier.
+
+     Use the best distance so far so that a candidate is only set if
+     a macro is better than anything so far.  This allows early rejection
+     (without calculating the edit distance) of macro names that must have
+     distance >= bm.get_best_distance (), and means that we only get a
+     non-NULL result for best_macro_match if it's better than any of
+     the identifiers already checked.  */
+  best_macro_match bmm (name, bm.get_best_distance (), parse_in);
+  cpp_hashnode *best_macro = bmm.get_best_meaningful_candidate ();
+  /* If a macro is the closest so far to NAME, suggest it.  */
+  if (best_macro)
+    return (const char *)best_macro->ident.str;
+
+  /* Try the "starts_decl_specifier_p" keywords to detect
+     "singed" vs "signed" typos.  */
+  for (unsigned i = 0; i < num_c_common_reswords; i++)
+    {
+      const c_common_resword *resword = &c_common_reswords[i];
+
+      if (!cp_keyword_starts_decl_specifier_p (resword->rid))
+	continue;
+
+      tree resword_identifier = ridpointers [resword->rid];
+      if (!resword_identifier)
+	continue;
+      gcc_assert (TREE_CODE (resword_identifier) == IDENTIFIER_NODE);
+      bm.consider (resword_identifier);
+    }
+
+  /* See if we have a good suggesion for the user.  */
+  tree best_id = bm.get_best_meaningful_candidate ();
+  if (best_id)
+    return IDENTIFIER_POINTER (best_id);
+
+  /* No meaningful suggestion available.  */
+  return NULL;
+}
+
 /* Subroutine of outer_binding.
 
    Returns TRUE if BINDING is a binding to a template parameter of
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 0a0f67b..7df75d6 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -40,6 +40,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "c-family/c-indentation.h"
 #include "context.h"
 #include "cp-cilkplus.h"
+#include "gcc-rich-location.h"
 
 
 /* The lexer.  */
@@ -937,15 +938,12 @@ cp_lexer_next_token_is_not_keyword (cp_lexer* lexer, enum rid keyword)
   return cp_lexer_peek_token (lexer)->keyword != keyword;
 }
 
-/* Return true if the next token is a keyword for a decl-specifier.  */
+/* Return true if KEYWORD can start a decl-specifier.  */
 
-static bool
-cp_lexer_next_token_is_decl_specifier_keyword (cp_lexer *lexer)
+bool
+cp_keyword_starts_decl_specifier_p (enum rid keyword)
 {
-  cp_token *token;
-
-  token = cp_lexer_peek_token (lexer);
-  switch (token->keyword) 
+  switch (keyword)
     {
       /* auto specifier: storage-class-specifier in C++,
          simple-type-specifier in C++0x.  */
@@ -985,14 +983,25 @@ cp_lexer_next_token_is_decl_specifier_keyword (cp_lexer *lexer)
       return true;
 
     default:
-      if (token->keyword >= RID_FIRST_INT_N
-	  && token->keyword < RID_FIRST_INT_N + NUM_INT_N_ENTS
-	  && int_n_enabled_p[token->keyword - RID_FIRST_INT_N])
+      if (keyword >= RID_FIRST_INT_N
+	  && keyword < RID_FIRST_INT_N + NUM_INT_N_ENTS
+	  && int_n_enabled_p[keyword - RID_FIRST_INT_N])
 	return true;
       return false;
     }
 }
 
+/* Return true if the next token is a keyword for a decl-specifier.  */
+
+static bool
+cp_lexer_next_token_is_decl_specifier_keyword (cp_lexer *lexer)
+{
+  cp_token *token;
+
+  token = cp_lexer_peek_token (lexer);
+  return cp_keyword_starts_decl_specifier_p (token->keyword);
+}
+
 /* Returns TRUE iff the token T begins a decltype type.  */
 
 static bool
@@ -3154,7 +3163,19 @@ cp_parser_diagnose_invalid_type_name (cp_parser *parser, tree id,
   else if (!parser->scope)
     {
       /* Issue an error message.  */
-      error_at (location, "%qE does not name a type", id);
+      const char *suggestion = NULL;
+      if (TREE_CODE (id) == IDENTIFIER_NODE)
+        suggestion = lookup_name_fuzzy (id, FUZZY_LOOKUP_TYPENAME);
+      if (suggestion)
+	{
+	  gcc_rich_location richloc (location);
+	  richloc.add_fixit_misspelled_id (location, suggestion);
+	  error_at_rich_loc (&richloc,
+			     "%qE does not name a type; did you mean %qs?",
+			     id, suggestion);
+	}
+      else
+	error_at (location, "%qE does not name a type", id);
       /* If we're in a template class, it's possible that the user was
 	 referring to a type from a base class.  For example:
 
diff --git a/gcc/cp/parser.h b/gcc/cp/parser.h
index ccbace9..2923378 100644
--- a/gcc/cp/parser.h
+++ b/gcc/cp/parser.h
@@ -420,5 +420,6 @@ extern void debug (vec<cp_token, va_gc> *ptr);
 extern void cp_debug_parser (FILE *, cp_parser *);
 extern void debug (cp_parser &ref);
 extern void debug (cp_parser *ptr);
+extern bool cp_keyword_starts_decl_specifier_p (enum rid keyword);
 
 #endif  /* GCC_CP_PARSER_H  */
diff --git a/gcc/cp/search.c b/gcc/cp/search.c
index 990c3fe..4a862b7 100644
--- a/gcc/cp/search.c
+++ b/gcc/cp/search.c
@@ -1407,6 +1407,10 @@ lookup_field_fuzzy_info::fuzzy_lookup_field (tree type)
        The TYPE_FIELDS of TYPENAME_TYPE is its TYPENAME_TYPE_FULLNAME.  */
     return;
 
+  /* TYPE_FIELDS is not valid for a TYPE_PACK_EXPANSION.  */
+  if (TREE_CODE (type) == TYPE_PACK_EXPANSION)
+    return;
+
   for (tree field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
     {
       if (!m_want_type_p || DECL_DECLARES_TYPE_P (field))
diff --git a/gcc/testsuite/g++.dg/spellcheck-identifiers-2.C b/gcc/testsuite/g++.dg/spellcheck-identifiers-2.C
new file mode 100644
index 0000000..59a8ec5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/spellcheck-identifiers-2.C
@@ -0,0 +1,43 @@
+/* PR c/71858 */
+/* Make sure anticipated builtins are not considered before they are declared.  */
+/* { dg-do compile } */
+/* { dg-options "-fdiagnostics-show-caret" } */
+
+int sscafn (const char *, const char *, ...);
+
+int
+test_1 (const char *p)
+{
+  int i;
+  return ssacnf (p, "%d", &i); /* { dg-error "10: .ssacnf. was not declared in this scope" } */
+  /* { dg-begin-multiline-output "" }
+   return ssacnf (p, "%d", &i);
+          ^~~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "10: suggested alternative: 'sscafn'" "" { target *-*-* } 12 }
+  /* { dg-begin-multiline-output "" }
+   return ssacnf (p, "%d", &i);
+          ^~~~~~
+          sscafn
+   { dg-end-multiline-output "" } */
+}
+
+int scafn (const char *, ...);
+int scanf (const char *, ...);
+
+int
+test_2 (void)
+{
+  int i;
+  return sacnf ("%d", &i); /* { dg-error "10: .sacnf. was not declared in this scope" } */
+  /* { dg-begin-multiline-output "" }
+   return sacnf ("%d", &i);
+          ^~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "10: suggested alternative: 'scanf'" "" { target *-*-* } 32 }
+  /* { dg-begin-multiline-output "" }
+   return sacnf ("%d", &i);
+          ^~~~~
+          scanf
+   { dg-end-multiline-output "" } */
+}
diff --git a/gcc/testsuite/g++.dg/spellcheck-identifiers.C b/gcc/testsuite/g++.dg/spellcheck-identifiers.C
new file mode 100644
index 0000000..0843439
--- /dev/null
+++ b/gcc/testsuite/g++.dg/spellcheck-identifiers.C
@@ -0,0 +1,255 @@
+/* { dg-do compile } */
+/* { dg-options "-fdiagnostics-show-caret" } */
+
+typedef struct GtkWidget { int dummy; } GtkWidget;
+
+extern void gtk_widget_show_all (GtkWidget *w);
+
+
+void
+test_1 (GtkWidget *w)
+{
+  gtk_widget_showall (w); // { dg-error "3: 'gtk_widget_showall' was not declared in this scope" }
+  /* { dg-begin-multiline-output "" }
+   gtk_widget_showall (w);
+   ^~~~~~~~~~~~~~~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "3: suggested alternative: 'gtk_widget_show_all'" "" { target *-*-* } 12 }
+  /* { dg-begin-multiline-output "" }
+   gtk_widget_showall (w);
+   ^~~~~~~~~~~~~~~~~~
+   gtk_widget_show_all
+   { dg-end-multiline-output "" } */
+
+  /* Ensure we don't try to suggest "gtk_widget_showall" for subsequent
+     corrections.  */
+  gtk_widget_showall_ (w); // { dg-error "3: 'gtk_widget_showall_' was not declared in this scope" }
+  /* { dg-begin-multiline-output "" }
+   gtk_widget_showall_ (w);
+   ^~~~~~~~~~~~~~~~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "3: suggested alternative: 'gtk_widget_show_all'" "" { target *-*-* } 26 }
+  /* { dg-begin-multiline-output "" }
+   gtk_widget_showall_ (w);
+   ^~~~~~~~~~~~~~~~~~~
+   gtk_widget_show_all
+   { dg-end-multiline-output "" } */
+
+  GtkWidgetShowAll (w); // { dg-error "3: 'GtkWidgetShowAll' was not declared in this scope" }
+  /* { dg-begin-multiline-output "" }
+   GtkWidgetShowAll (w);
+   ^~~~~~~~~~~~~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "3: suggested alternative: 'gtk_widget_show_all'" "" { target *-*-* } 38 }
+  /* { dg-begin-multiline-output "" }
+   GtkWidgetShowAll (w);
+   ^~~~~~~~~~~~~~~~
+   gtk_widget_show_all
+   { dg-end-multiline-output "" } */
+}
+
+int
+test_2 (int param)
+{
+  return parma * parma; // { dg-error "10: 'parma' was not declared in this scope" }
+  /* { dg-begin-multiline-output "" }
+   return parma * parma;
+          ^~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "10: suggested alternative: 'param'" "" { target *-*-* } 54 }
+  /* { dg-begin-multiline-output "" }
+   return parma * parma;
+          ^~~~~
+          param
+   { dg-end-multiline-output "" } */
+}
+
+#define MACRO(X) ((X))
+
+int
+test_3 (int i)
+{
+  return MACRAME (i); // { dg-error "10: 'MACRAME' was not declared in this scope" }
+  /* { dg-begin-multiline-output "" }
+   return MACRAME (i);
+          ^~~~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "10: suggested alternative: 'MACRO'" "" { target *-*-* } 72 }
+  /* { dg-begin-multiline-output "" }
+   return MACRAME (i);
+          ^~~~~~~
+          MACRO
+   { dg-end-multiline-output "" } */
+}
+
+#define IDENTIFIER_POINTER(X) ((X))
+
+int
+test_4 (int node)
+{
+  return IDENTIFIER_PTR (node); // { dg-error "10: 'IDENTIFIER_PTR' was not declared in this scope" }
+  /* { dg-begin-multiline-output "" }
+   return IDENTIFIER_PTR (node);
+          ^~~~~~~~~~~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "10: suggested alternative: 'IDENTIFIER_POINTER'" "" { target *-*-* } 90 }
+  /* { dg-begin-multiline-output "" }
+   return IDENTIFIER_PTR (node);
+          ^~~~~~~~~~~~~~
+          IDENTIFIER_POINTER
+   { dg-end-multiline-output "" } */
+}
+
+
+int
+test_5 (void)
+{
+  return __LINE_; /* { dg-error "10: '__LINE_' was not declared in this scope" }
+  /* { dg-begin-multiline-output "" }
+   return __LINE_;
+          ^~~~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "10: suggested alternative: '__LINE__'" "" { target *-*-* } 107 }
+  /* { dg-begin-multiline-output "" }
+   return __LINE_;
+          ^~~~~~~
+          __LINE__
+   { dg-end-multiline-output "" } */
+}
+
+#define MAX_ITEMS 100
+int array[MAX_ITEM]; // { dg-error "11: 'MAX_ITEM' was not declared in this scope" }
+  /* { dg-begin-multiline-output "" }
+ int array[MAX_ITEM];
+           ^~~~~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "11: suggested alternative: 'MAX_ITEMS'" "" { target *-*-* } 121 }
+  /* { dg-begin-multiline-output "" }
+ int array[MAX_ITEM];
+           ^~~~~~~~
+           MAX_ITEMS
+   { dg-end-multiline-output "" } */
+
+
+enum foo {
+  FOO_FIRST,
+  FOO_SECOND
+};
+
+int
+test_6 (enum foo f)
+{
+  switch (f)
+    {
+    case FOO_FURST: // { dg-error "10: 'FOO_FURST' was not declared in this scope" }
+      break;
+  /* { dg-begin-multiline-output "" }
+     case FOO_FURST:
+          ^~~~~~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "10: suggested alternative: 'FOO_FIRST'" "" { target *-*-* } 144 }
+  /* { dg-begin-multiline-output "" }
+     case FOO_FURST:
+          ^~~~~~~~~
+          FOO_FIRST
+   { dg-end-multiline-output "" } */
+
+    case FOO_SECCOND: // { dg-error "10: 'FOO_SECCOND' was not declared in this scope" }
+      break;
+  /* { dg-begin-multiline-output "" }
+     case FOO_SECCOND:
+          ^~~~~~~~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "10: suggested alternative: 'FOO_SECOND'" "" { target *-*-* } 157 }
+  /* { dg-begin-multiline-output "" }
+     case FOO_SECCOND:
+          ^~~~~~~~~~~
+          FOO_SECOND
+   { dg-end-multiline-output "" } */
+
+    default:
+      break;
+    }
+}
+
+int snprintf (char *, __SIZE_TYPE__, const char *, ...);
+
+void
+test_7 (int i, int j)
+{
+  int buffer[100];
+  snprint (buffer, 100, "%i of %i", i, j); // { dg-error "3: 'snprint' was not declared in this scope" }
+  /* { dg-begin-multiline-output "" }
+   snprint (buffer, 100, "%i of %i", i, j);
+   ^~~~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "3: suggested alternative: 'snprintf'" "" { target *-*-* } 181 }
+  /* { dg-begin-multiline-output "" }
+   snprint (buffer, 100, "%i of %i", i, j);
+   ^~~~~~~
+   snprintf
+   { dg-end-multiline-output "" } */
+}
+
+int
+test_8 ()
+{
+  int local = 42;
+  
+  return locale; // { dg-error "10: 'locale' was not declared in this scope" }
+  /* { dg-begin-multiline-output "" }
+   return locale;
+          ^~~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "10: suggested alternative: 'local'" "" { target *-*-* } 199 }
+  /* { dg-begin-multiline-output "" }
+   return locale;
+          ^~~~~~
+          local
+   { dg-end-multiline-output "" } */
+}
+
+class base
+{
+public:
+  int test_method_1 ();
+
+protected:
+  int m_foo;
+};
+
+class sub : public base
+{
+public:
+  int test_method_2 ();
+};
+
+int base::test_method_1 ()
+{
+  return m_food; // { dg-error "10: 'm_food' was not declared in this scope" }
+  /* { dg-begin-multiline-output "" }
+   return m_food;
+          ^~~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "10: suggested alternative: 'm_foo'" "" { target *-*-* } 229 }
+  /* { dg-begin-multiline-output "" }
+   return m_food;
+          ^~~~~~
+          m_foo
+   { dg-end-multiline-output "" } */
+}
+
+int sub::test_method_2 ()
+{
+  return m_food; // { dg-error "10: 'm_food' was not declared in this scope" }
+  /* { dg-begin-multiline-output "" }
+   return m_food;
+          ^~~~~~
+   { dg-end-multiline-output "" } */
+  // { dg-message "10: suggested alternative: 'm_foo'" "" { target *-*-* } 244 }
+  /* { dg-begin-multiline-output "" }
+   return m_food;
+          ^~~~~~
+          m_foo
+   { dg-end-multiline-output "" } */
+}
diff --git a/gcc/testsuite/g++.dg/spellcheck-typenames.C b/gcc/testsuite/g++.dg/spellcheck-typenames.C
new file mode 100644
index 0000000..9aa5b72
--- /dev/null
+++ b/gcc/testsuite/g++.dg/spellcheck-typenames.C
@@ -0,0 +1,84 @@
+/* { dg-do compile } */
+/* { dg-options "-fdiagnostics-show-caret" } */
+
+void test_1 (signed char e);
+
+/* PR c/70339.  */
+void test_2 (singed char e); // { dg-error "21: variable or field 'test_2' declared void" }
+/* { dg-begin-multiline-output "" }
+ void test_2 (singed char e);
+                     ^~~~
+   { dg-end-multiline-output "" } */
+// { dg-message "14: 'singed' was not declared in this scope" "" { target *-*-* } 7 }
+/* { dg-begin-multiline-output "" }
+ void test_2 (singed char e);
+              ^~~~~~
+   { dg-end-multiline-output "" } */
+// { dg-message "14: suggested alternative: 'signed'" "" { target *-*-* } 7 }
+/* { dg-begin-multiline-output "" }
+ void test_2 (singed char e);
+              ^~~~~~
+              signed
+   { dg-end-multiline-output "" } */
+
+void test_3 (car e); // { dg-error "14: variable or field 'test_3' declared void" }
+/* { dg-begin-multiline-output "" }
+ void test_3 (car e);
+              ^~~
+   { dg-end-multiline-output "" } */
+// { dg-message "14: 'car' was not declared in this scope" "" { target *-*-* } 24 }
+// { dg-message "14: suggested alternative: 'char'" "" { target *-*-* } 24 }
+/* { dg-begin-multiline-output "" }
+ void test_3 (car e);
+              ^~~
+              char
+   { dg-end-multiline-output "" } */
+
+/* TODO: this one could be handled better.  */
+void test_4 (signed car e); // { dg-error "25: expected ',' or '...' before 'e'" }
+/* { dg-begin-multiline-output "" }
+ void test_4 (signed car e);
+                         ^
+   { dg-end-multiline-output "" } */
+
+/* Verify that we handle misspelled typedef names.  */
+
+typedef struct something {} something_t;
+
+some_thing_t test_5; // { dg-error "1: 'some_thing_t' does not name a type; did you mean 'something_t'?" }
+  /* { dg-begin-multiline-output "" }
+ some_thing_t test_5;
+ ^~~~~~~~~~~~
+ something_t
+   { dg-end-multiline-output "" } */
+
+/* TODO: we don't yet handle misspelled struct names.  */
+struct some_thing test_6; // { dg-error "aggregate 'some_thing test_6' has incomplete type and cannot be defined" }
+  /* { dg-begin-multiline-output "" }
+ struct some_thing test_6;
+                   ^~~~~~
+   { dg-end-multiline-output "" } */
+
+typedef long int64_t;
+int64 i; // { dg-error "1: 'int64' does not name a type; did you mean 'int64_t'?" }
+/* { dg-begin-multiline-output "" }
+ int64 i;
+ ^~~~~
+ int64_t
+   { dg-end-multiline-output "" } */
+
+/* Verify that gcc doesn't offer nonsensical suggestions.  */
+
+nonsensical_suggestion_t var; /* { dg-bogus "did you mean" } */
+/* { dg-error "'nonsensical_suggestion_t' does not name a type" "" { target { *-*-* } } 72 } */
+/* { dg-begin-multiline-output "" }
+ nonsensical_suggestion_t var;
+ ^~~~~~~~~~~~~~~~~~~~~~~~
+   { dg-end-multiline-output "" } */
+
+singed char ch; // { dg-error "1: 'singed' does not name a type; did you mean 'signed'?" }
+/* { dg-begin-multiline-output "" }
+ singed char ch;
+ ^~~~~~
+ signed
+   { dg-end-multiline-output "" } */
-- 
1.8.5.3