diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index 64d3a941cb9..011f0bf0a69 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -3493,12 +3493,12 @@ pushdecl (tree x)
 }
 
 
-/* Issue a warning about implicit function declaration.  ID is the function
+/* Issue a permerror about implicit function declaration.  ID is the function
    identifier, OLDDECL is a declaration of the function in a different scope,
    or NULL_TREE.  */
 
 static void
-implicit_decl_warning (location_t loc, tree id, tree olddecl)
+implicit_decl_permerror (location_t loc, tree id, tree olddecl)
 {
   if (!warn_implicit_function_declaration)
     return;
@@ -3515,14 +3515,14 @@ implicit_decl_warning (location_t loc, tree id, tree olddecl)
 	{
 	  gcc_rich_location richloc (loc);
 	  richloc.add_fixit_replace (suggestion);
-	  warned = pedwarn (&richloc, OPT_Wimplicit_function_declaration,
-			    "implicit declaration of function %qE;"
-			    " did you mean %qs?",
-			    id, suggestion);
+	  warned = permerror_opt (&richloc, OPT_Wimplicit_function_declaration,
+				  "implicit declaration of function %qE;"
+				  " did you mean %qs?",
+				  id, suggestion);
 	}
       else
-	warned = pedwarn (loc, OPT_Wimplicit_function_declaration,
-			  "implicit declaration of function %qE", id);
+	warned = permerror_opt (loc, OPT_Wimplicit_function_declaration,
+				"implicit declaration of function %qE", id);
     }
   else if (const char *suggestion = hint.suggestion ())
     {
@@ -3812,7 +3812,7 @@ implicitly_declare (location_t loc, tree functionid)
 	     then recycle the old declaration but with the new type.  */
 	  if (!C_DECL_IMPLICIT (decl))
 	    {
-	      implicit_decl_warning (loc, functionid, decl);
+	      implicit_decl_permerror (loc, functionid, decl);
 	      C_DECL_IMPLICIT (decl) = 1;
 	    }
 	  if (fndecl_built_in_p (decl))
@@ -3865,7 +3865,7 @@ implicitly_declare (location_t loc, tree functionid)
   DECL_EXTERNAL (decl) = 1;
   TREE_PUBLIC (decl) = 1;
   C_DECL_IMPLICIT (decl) = 1;
-  implicit_decl_warning (loc, functionid, 0);
+  implicit_decl_permerror (loc, functionid, 0);
   asmspec_tree = maybe_apply_renaming_pragma (decl, /*asmname=*/NULL);
   if (asmspec_tree)
     set_user_assembler_name (decl, TREE_STRING_POINTER (asmspec_tree));
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 6f748c3efd2..a12b8e63c79 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -6179,6 +6179,7 @@ only by this flag, but it also downgrades some C and C++ diagnostics
 that have their own flag:
 
 @gccoptlist{
+-Wimplicit-function-declaration @r{(C)}
 -Wint-conversion @r{(C)}
 -Wnarrowing @r{(C++)}
 }
@@ -6859,8 +6860,11 @@ This warning is upgraded to an error by @option{-pedantic-errors}.
 @opindex Wno-implicit-function-declaration
 @item -Wno-implicit-function-declaration @r{(C and Objective-C only)}
 This option controls warnings when a function is used before being declared.
-This warning is enabled by default in C99 and later dialects of C,
-and also by @option{-Wall}.
+This warning is enabled by default, as an error, in C99 and later
+dialects of C, and also by @option{-Wall}.  The error can be downgraded
+to a warning using @option{-fpermissive} (along with certain other
+errors), or for this error alone, with
+@option{-Wno-error=implicit-function-declaration}.
 
 This warning is upgraded to an error by @option{-pedantic-errors}.
 
diff --git a/gcc/testsuite/c-c++-common/spellcheck-reserved.c b/gcc/testsuite/c-c++-common/spellcheck-reserved.c
index 56e59dcc00a..0be35c56f52 100644
--- a/gcc/testsuite/c-c++-common/spellcheck-reserved.c
+++ b/gcc/testsuite/c-c++-common/spellcheck-reserved.c
@@ -29,7 +29,7 @@ SOME_MACRO foo; /* { dg-bogus "__SOME_MACRO" } */
 void test (const char *buf, char ch)
 {
   __builtin_strtchr (buf, ch); /* { dg-line misspelled_reserved } */
-  /* { dg-warning "did you mean '__builtin_strchr'" "" { target c } misspelled_reserved } */
+  /* { dg-error "did you mean '__builtin_strchr'" "" { target c } misspelled_reserved } */
   /* { dg-error "'__builtin_strtchr' was not declared in this scope; did you mean '__builtin_strrchr'\\?" "" { target c++ } misspelled_reserved } */
 }
 
@@ -38,7 +38,7 @@ void test (const char *buf, char ch)
 void test_2 (const char *buf, char ch)
 {
   _builtin_strchr (buf, ch); /* { dg-line misspelled_one_underscore } */
-  /* { dg-warning "did you mean '__builtin_strchr'" "" { target c } misspelled_one_underscore } */
+  /* { dg-error "did you mean '__builtin_strchr'" "" { target c } misspelled_one_underscore } */
   /* { dg-error "'_builtin_strchr' was not declared in this scope; did you mean '__builtin_strchr'\\?" "" { target c++ } misspelled_one_underscore } */
 }
 
diff --git a/gcc/testsuite/gcc.dg/Wimplicit-function-declaration-c99-2.c b/gcc/testsuite/gcc.dg/Wimplicit-function-declaration-c99-2.c
new file mode 100644
index 00000000000..d65abc9670c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wimplicit-function-declaration-c99-2.c
@@ -0,0 +1,7 @@
+/* { dg-do compile } */
+/* { dg-options "-std=c99" } */
+
+void f(void) 
+{ 
+  puts("Hello"); /* { dg-error "implicit declaration of function" } */
+}
diff --git a/gcc/testsuite/gcc.dg/Wimplicit-function-declaration-c99.c b/gcc/testsuite/gcc.dg/Wimplicit-function-declaration-c99.c
index 254f7e70e65..abea8a5f356 100644
--- a/gcc/testsuite/gcc.dg/Wimplicit-function-declaration-c99.c
+++ b/gcc/testsuite/gcc.dg/Wimplicit-function-declaration-c99.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-std=c99" } */
+/* { dg-options "-fpermissive -std=c99" } */
 
 void f(void) 
 { 
diff --git a/gcc/testsuite/gcc.dg/missing-header-fixit-1.c b/gcc/testsuite/gcc.dg/missing-header-fixit-1.c
index 2b28357e1db..eb33d9b1f23 100644
--- a/gcc/testsuite/gcc.dg/missing-header-fixit-1.c
+++ b/gcc/testsuite/gcc.dg/missing-header-fixit-1.c
@@ -5,7 +5,7 @@
 /* This is padding (to avoid the generated patch containing DejaGnu
    directives).  */
 
-/* { dg-options "-fdiagnostics-generate-patch" } */
+/* { dg-options "-fpermissive -fdiagnostics-generate-patch" } */
 
 void test (int i, int j)
 {
diff --git a/gcc/testsuite/gcc.dg/missing-header-fixit-1a.c b/gcc/testsuite/gcc.dg/missing-header-fixit-1a.c
new file mode 100644
index 00000000000..e47236b955d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/missing-header-fixit-1a.c
@@ -0,0 +1,37 @@
+/* Example of a fix-it hint that adds a #include directive,
+   adding them to the top of the file, given that there is no
+   pre-existing #include.  */
+
+/* This is padding (to avoid the generated patch containing DejaGnu
+   directives).  */
+
+/* { dg-options "-fdiagnostics-generate-patch" } */
+
+void test (int i, int j)
+{
+  printf ("%i of %i\n", i, j); /* { dg-error "implicit declaration" } */
+  /* { dg-message "include '<stdio.h>' or provide a declaration of 'printf'" "" { target *-*-* } .-1 } */
+  /* { dg-warning "incompatible implicit declaration of built-in function 'printf'" "" { target *-*-* } .-2 } */
+}
+
+/* Verify the output from -fdiagnostics-generate-patch.
+   We expect the patch to begin with a header, containing this
+   source filename, via an absolute path.
+   Given the path, we can only capture it via regexps.  */
+/* { dg-regexp "\\-\\-\\- .*" } */
+/* { dg-regexp "\\+\\+\\+ .*" } */
+/* Use #if 0/#endif rather than comments, to allow the text to contain
+   a comment.  */
+#if 0
+{ dg-begin-multiline-output "" }
+@@ -1,3 +1,4 @@
++#include <stdio.h>
+ /* Example of a fix-it hint that adds a #include directive,
+    adding them to the top of the file, given that there is no
+    pre-existing #include.  */
+{ dg-end-multiline-output "" }
+#endif
+
+/* FIXME: should we attempt to skip leading comments when determining the
+   insertion location?
+   Similarly, should we attempt to be within single-inclusion guards, etc?  */
diff --git a/gcc/testsuite/gcc.dg/missing-header-fixit-2.c b/gcc/testsuite/gcc.dg/missing-header-fixit-2.c
index 5d5f87488f5..38d36a66c46 100644
--- a/gcc/testsuite/gcc.dg/missing-header-fixit-2.c
+++ b/gcc/testsuite/gcc.dg/missing-header-fixit-2.c
@@ -9,7 +9,7 @@
 /* { dg-warning "implicit declaration of function 'printf'" "" { target *-*-* } 6 } */
 /* { dg-warning "incompatible implicit declaration of built-in function 'printf'" "" { target *-*-* } 6 } */
 
-/* { dg-options "-fdiagnostics-generate-patch" } */
+/* { dg-options "-fpermissive -fdiagnostics-generate-patch" } */
 
 /* Verify the output from -fdiagnostics-generate-patch.
    We expect the patch to begin with a header, containing the
diff --git a/gcc/testsuite/gcc.dg/missing-header-fixit-2a.c b/gcc/testsuite/gcc.dg/missing-header-fixit-2a.c
new file mode 100644
index 00000000000..4ae617bddbd
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/missing-header-fixit-2a.c
@@ -0,0 +1,31 @@
+/* Verify that when we suggest adding #include directives that they
+   are added to the affected file.  */
+
+/* The following header file is missing a "#include <stdio.h>".  */
+
+#include "missing-header-fixit-2.h"
+
+/* These directives actually apply to the header.  */
+/* { dg-error "implicit declaration of function 'printf'" "" { target *-*-* } 6 } */
+/* { dg-warning "incompatible implicit declaration of built-in function 'printf'" "" { target *-*-* } 6 } */
+
+/* { dg-options "-fdiagnostics-generate-patch" } */
+
+/* Verify the output from -fdiagnostics-generate-patch.
+   We expect the patch to begin with a header, containing the
+   filename of the header, via an absolute path.
+   Given the path, we can only capture it via regexps.  */
+/* { dg-regexp "\\-\\-\\- .*" } */
+/* { dg-regexp "\\+\\+\\+ .*" } */
+/* Use #if 0/#endif rather than comments, to allow the text to contain
+   a comment.
+   We expect the *header* to have been patched, adding the missing include.  */
+#if 0
+{ dg-begin-multiline-output "" }
+@@ -1,3 +1,4 @@
++#include <stdio.h>
+ /* This is missing-header-fixit-2.h, for use by
+    missing-header-fixit-2.c  */
+ 
+{ dg-end-multiline-output "" }
+#endif
diff --git a/gcc/testsuite/gcc.dg/missing-header-fixit-4.c b/gcc/testsuite/gcc.dg/missing-header-fixit-4.c
index b6680563dc1..8e4e48d2e43 100644
--- a/gcc/testsuite/gcc.dg/missing-header-fixit-4.c
+++ b/gcc/testsuite/gcc.dg/missing-header-fixit-4.c
@@ -3,7 +3,7 @@
 #include "empty.h"
 int the_next_line;
 
-/* { dg-options "-fdiagnostics-show-caret -fdiagnostics-show-line-numbers" } */
+/* { dg-options "-fpermissive -fdiagnostics-show-caret -fdiagnostics-show-line-numbers" } */
 
 void test (int i, int j)
 {
diff --git a/gcc/testsuite/gcc.dg/missing-header-fixit-4a.c b/gcc/testsuite/gcc.dg/missing-header-fixit-4a.c
new file mode 100644
index 00000000000..b93061f287b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/missing-header-fixit-4a.c
@@ -0,0 +1,27 @@
+/* Example of a fix-it hint that adds a #include directive,
+   adding them after a pre-existing #include directive.  */
+#include "empty.h"
+int the_next_line;
+
+/* { dg-options "-fdiagnostics-show-caret -fdiagnostics-show-line-numbers" } */
+
+void test (int i, int j)
+{
+  printf ("%i of %i\n", i, j); /* { dg-line printf } */
+  /* { dg-error "implicit declaration of function" "" { target *-*-* } printf } */
+  /* { dg-begin-multiline-output "" }
+   10 |   printf ("%i of %i\n", i, j);
+      |   ^~~~~~
+   { dg-end-multiline-output "" } */
+  /* { dg-warning "incompatible implicit declaration" "" { target *-*-* } printf } */
+  /* { dg-begin-multiline-output "" }
+   10 |   printf ("%i of %i\n", i, j);
+      |   ^~~~~~
+   { dg-end-multiline-output "" } */
+  /* { dg-message "include '<stdio.h>' or provide a declaration of 'printf'" "" { target *-*-* } 4 } */
+  /* { dg-begin-multiline-output "" }
+    3 | #include "empty.h"
+  +++ |+#include <stdio.h>
+    4 | int the_next_line;
+   { dg-end-multiline-output "" } */
+}
diff --git a/gcc/testsuite/gcc.dg/missing-header-fixit-5.c b/gcc/testsuite/gcc.dg/missing-header-fixit-5.c
index bf44feb24a9..c34a47dc286 100644
--- a/gcc/testsuite/gcc.dg/missing-header-fixit-5.c
+++ b/gcc/testsuite/gcc.dg/missing-header-fixit-5.c
@@ -3,7 +3,7 @@
    Rely on -Wimplicit-function-declaration for fixit hints, not on
    -Wbuiltin-declaration-mismatch (which misses abs, isdigit, putchar).  */
 
-/* { dg-options "-fdiagnostics-show-caret -fdiagnostics-show-line-numbers -Wimplicit-function-declaration -Wno-builtin-declaration-mismatch" } */
+/* { dg-options "-fpermissive -fdiagnostics-show-caret -fdiagnostics-show-line-numbers -Wimplicit-function-declaration -Wno-builtin-declaration-mismatch" } */
 
 int
 foo (char *m, int i)
diff --git a/gcc/testsuite/gcc.dg/missing-header-fixit-5a.c b/gcc/testsuite/gcc.dg/missing-header-fixit-5a.c
new file mode 100644
index 00000000000..420cbf7be40
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/missing-header-fixit-5a.c
@@ -0,0 +1,42 @@
+
+/* Forget to include any standard headers, all for built-in functions.
+   Rely on -Wimplicit-function-declaration for fixit hints, not on
+   -Wbuiltin-declaration-mismatch (which misses abs, isdigit, putchar).  */
+
+/* { dg-options "-fdiagnostics-show-caret -fdiagnostics-show-line-numbers -Wimplicit-function-declaration -Wno-builtin-declaration-mismatch" } */
+
+int
+foo (char *m, int i)
+{
+  if (isdigit (m[0])) /* { dg-error "implicit declaration of function" } */
+  /* { dg-begin-multiline-output "" }
+   11 |   if (isdigit (m[0]))
+      |       ^~~~~~~
+     { dg-end-multiline-output "" } */
+  /* { dg-begin-multiline-output "" }
+  +++ |+#include <ctype.h>
+    1 | 
+     { dg-end-multiline-output "" } */
+    {
+      return abs (i); /* { dg-error "implicit declaration of function" } */
+  /* { dg-begin-multiline-output "" }
+   21 |       return abs (i);
+      |              ^~~
+     { dg-end-multiline-output "" } */
+  /* { dg-begin-multiline-output "" }
+  +++ |+#include <stdlib.h>
+    1 | 
+     { dg-end-multiline-output "" } */
+    }
+  else
+    putchar (m[0]); /* { dg-error "implicit declaration of function" } */
+  /* { dg-begin-multiline-output "" }
+   32 |     putchar (m[0]);
+      |     ^~~~~~~
+     { dg-end-multiline-output "" } */
+  /* { dg-begin-multiline-output "" }
+  +++ |+#include <stdio.h>
+    1 | 
+     { dg-end-multiline-output "" } */
+  return i;
+}
diff --git a/gcc/testsuite/gcc.dg/permerror-default.c b/gcc/testsuite/gcc.dg/permerror-default.c
index 5235a427175..f37f9189e41 100644
--- a/gcc/testsuite/gcc.dg/permerror-default.c
+++ b/gcc/testsuite/gcc.dg/permerror-default.c
@@ -7,7 +7,7 @@
 void
 implicit_function_declaration (void)
 {
-  f1 (); /* { dg-warning "'f1' \\\[-Wimplicit-function-declaration\\\]" } */
+  f1 (); /* { dg-error "'f1' \\\[-Wimplicit-function-declaration\\\]" } */
 }
 
 extern implicit_int_1; /* { dg-warning "'implicit_int_1' \\\[-Wimplicit-int\\\]" } */
diff --git a/gcc/testsuite/gcc.dg/permerror-system.c b/gcc/testsuite/gcc.dg/permerror-system.c
index 75e08887ef1..e4da4a99e9a 100644
--- a/gcc/testsuite/gcc.dg/permerror-system.c
+++ b/gcc/testsuite/gcc.dg/permerror-system.c
@@ -8,6 +8,8 @@
 
 /* These errors come from permerror-default.c.  */
 
+/* { dg-error "'f1' \\\[-Wimplicit-function-declaration\\\]" "" { target *-*-* } 10 } */
+
 /* { dg-error "pointer/integer type mismatch in conditional expression \\\[-Wint-conversion\\\]" "" { target *-*-* } 29 } */
 /* { dg-error "pointer/integer type mismatch in conditional expression \\\[-Wint-conversion\\\]" "" { target *-*-* } 30 } */
 /* { dg-error "passing argument 1 of 'f2' makes pointer from integer without a cast \\\[-Wint-conversion\\\]" "" { target *-*-* } 31 } */
diff --git a/gcc/testsuite/gcc.dg/pr61852.c b/gcc/testsuite/gcc.dg/pr61852.c
index f488aca7ac2..e669d3c4d39 100644
--- a/gcc/testsuite/gcc.dg/pr61852.c
+++ b/gcc/testsuite/gcc.dg/pr61852.c
@@ -1,10 +1,10 @@
 /* PR c/61852 */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-function-declaration" } */
+/* { dg-options "" } */
 
 int
 f (int a)
 {
-  int b = a + a + a + ff (a); /* { dg-warning "23:implicit declaration of function" } */
+  int b = a + a + a + ff (a); /* { dg-error "23:implicit declaration of function" } */
   return b;
 }
diff --git a/gcc/testsuite/gcc.dg/spellcheck-identifiers-1a.c b/gcc/testsuite/gcc.dg/spellcheck-identifiers-1a.c
new file mode 100644
index 00000000000..f50c52b656c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/spellcheck-identifiers-1a.c
@@ -0,0 +1,136 @@
+/* { 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: implicit declaration of function .gtk_widget_showall.; did you mean .gtk_widget_show_all.?" } */
+  /* { 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: implicit declaration of function .gtk_widget_showall_.; did you mean .gtk_widget_show_all.?" } */
+  /* { dg-begin-multiline-output "" }
+   gtk_widget_showall_ (w);
+   ^~~~~~~~~~~~~~~~~~~
+   gtk_widget_show_all
+   { dg-end-multiline-output "" } */
+
+  GtkWidgetShowAll (w); /* { dg-error "3: implicit declaration of function .GtkWidgetShowAll.; did you mean .gtk_widget_show_all.?" } */
+  /* { 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. undeclared .first use in this function.; did you mean .param." } */
+  /* { 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: implicit declaration of function .MACRAME.; did you mean .MACRO.?" } */
+  /* { 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: implicit declaration of function .IDENTIFIER_PTR.; did you mean .IDENTIFIER_POINTER.?" } */
+  /* { dg-begin-multiline-output "" }
+   return IDENTIFIER_PTR (node);
+          ^~~~~~~~~~~~~~
+          IDENTIFIER_POINTER
+   { dg-end-multiline-output "" } */
+}
+
+
+int
+test_5 (void)
+{
+  return __LINE_; /* { dg-error "10: .__LINE_. undeclared .first use in this function.; did you mean .__LINE__." } */
+  /* { dg-begin-multiline-output "" }
+   return __LINE_;
+          ^~~~~~~
+          __LINE__
+   { dg-end-multiline-output "" } */
+}
+
+#define MAX_ITEMS 100
+int array[MAX_ITEM]; /* { dg-error "11: .MAX_ITEM. undeclared here .not in a function.; did you mean .MAX_ITEMS." } */
+  /* { 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. undeclared .first use in this function.; did you mean .FOO_FIRST." } */
+      break;
+  /* { dg-begin-multiline-output "" }
+     case FOO_FURST:
+          ^~~~~~~~~
+          FOO_FIRST
+   { dg-end-multiline-output "" } */
+
+    case FOO_SECCOND: /* { dg-error "10: .FOO_SECCOND. undeclared .first use in this function.; did you mean .FOO_SECOND." } */
+      break;
+  /* { 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: implicit declaration of function .snprint.; did you mean .snprintf.." } */
+  /* { dg-begin-multiline-output "" }
+   snprint (buffer, 100, "%i of %i", i, j);
+   ^~~~~~~
+   snprintf
+   { dg-end-multiline-output "" } */
+}
diff --git a/gcc/testsuite/gcc.dg/spellcheck-identifiers-2.c b/gcc/testsuite/gcc.dg/spellcheck-identifiers-2.c
index ad6e9d3191d..b49709dc528 100644
--- a/gcc/testsuite/gcc.dg/spellcheck-identifiers-2.c
+++ b/gcc/testsuite/gcc.dg/spellcheck-identifiers-2.c
@@ -1,7 +1,7 @@
 /* PR c/71858 */
 /* Make sure anticipated builtins are not considered before they are declared.  */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-function-declaration -fdiagnostics-show-caret" } */
+/* { dg-options "-fpermissive -Wimplicit-function-declaration -fdiagnostics-show-caret" } */
 
 int sscafn (const char *, const char *, ...);
 
diff --git a/gcc/testsuite/gcc.dg/spellcheck-identifiers-2a.c b/gcc/testsuite/gcc.dg/spellcheck-identifiers-2a.c
new file mode 100644
index 00000000000..1a3e68c703c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/spellcheck-identifiers-2a.c
@@ -0,0 +1,33 @@
+/* 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: implicit declaration of function .ssacnf.; did you mean .sscafn.?" } */
+  /* { 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: implicit declaration of function .sacnf.; did you mean .scanf.?" } */
+  /* { dg-begin-multiline-output "" }
+   return sacnf ("%d", &i);
+          ^~~~~
+          scanf
+   { dg-end-multiline-output "" } */
+}
diff --git a/gcc/testsuite/gcc.dg/spellcheck-identifiers-3.c b/gcc/testsuite/gcc.dg/spellcheck-identifiers-3.c
index 94f4078d0e8..0b5982fa705 100644
--- a/gcc/testsuite/gcc.dg/spellcheck-identifiers-3.c
+++ b/gcc/testsuite/gcc.dg/spellcheck-identifiers-3.c
@@ -1,7 +1,7 @@
 /* PR c/71858 */
 /* Only consider function names, function pointers and macros for implicit function declarations.  */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-function-declaration -fdiagnostics-show-caret" } */
+/* { dg-options "-fpermissive -Wimplicit-function-declaration -fdiagnostics-show-caret" } */
 
 void fn1abcd (void);
 
diff --git a/gcc/testsuite/gcc.dg/spellcheck-identifiers-3a.c b/gcc/testsuite/gcc.dg/spellcheck-identifiers-3a.c
new file mode 100644
index 00000000000..0c0a19e547b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/spellcheck-identifiers-3a.c
@@ -0,0 +1,45 @@
+/* PR c/71858 */
+/* Only consider function names, function pointers and macros for implicit function declarations.  */
+/* { dg-do compile } */
+/* { dg-options "-fdiagnostics-show-caret" } */
+
+void fn1abcd (void);
+
+void
+test_1 (int fn1bacd)
+{
+  fn1badc (); /* { dg-error "3: implicit declaration of function .fn1badc.; did you mean .fn1abcd.?" } */
+  /* { dg-begin-multiline-output "" }
+   fn1badc ();
+   ^~~~~~~
+   fn1abcd
+   { dg-end-multiline-output "" } */
+}
+
+void fn2efgh (void);
+void (*fn2efhg) (void);
+
+void
+test_2 (void)
+{
+  fn2fehg (); /* { dg-error "3: implicit declaration of function .fn2fehg.; did you mean .fn2efhg.?" } */
+  /* { dg-begin-multiline-output "" }
+   fn2fehg ();
+   ^~~~~~~
+   fn2efhg
+   { dg-end-multiline-output "" } */
+}
+
+void fn3ijkl (void);
+typedef int fn3ijlk;
+
+void
+test_3 (void)
+{
+  fn3jilk (); /* { dg-error "3: implicit declaration of function .fn3jilk.; did you mean .fn3ijkl.?" } */
+  /* { dg-begin-multiline-output "" }
+   fn3jilk ();
+   ^~~~~~~
+   fn3ijkl
+   { dg-end-multiline-output "" } */
+}
diff --git a/gcc/testsuite/gcc.dg/spellcheck-identifiers-4.c b/gcc/testsuite/gcc.dg/spellcheck-identifiers-4.c
index f9b7d8d0cab..f24d863a15c 100644
--- a/gcc/testsuite/gcc.dg/spellcheck-identifiers-4.c
+++ b/gcc/testsuite/gcc.dg/spellcheck-identifiers-4.c
@@ -1,4 +1,4 @@
-/* { dg-options "-Wimplicit-function-declaration" } */
+/* { dg-options "-fpermissive -Wimplicit-function-declaration" } */
 
 extern double sqrt (double);
 
diff --git a/gcc/testsuite/gcc.dg/spellcheck-identifiers-4a.c b/gcc/testsuite/gcc.dg/spellcheck-identifiers-4a.c
new file mode 100644
index 00000000000..33a6b4220f4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/spellcheck-identifiers-4a.c
@@ -0,0 +1,10 @@
+/* { dg-options "" } */
+
+extern double sqrt (double);
+
+void test (float pf, float inff)
+{
+  assert (pf == inff); /* { dg-bogus "sqrt" } */
+  /* { dg-error "implicit declaration of function 'assert'" "" { target *-*-* } .-1 } */
+  /* { dg-message "header '<assert.h>'" "" { target *-*-* } .-2 } */
+}
diff --git a/gcc/testsuite/gcc.dg/spellcheck-identifiers.c b/gcc/testsuite/gcc.dg/spellcheck-identifiers.c
index 063e3f9eda1..cd632c6a064 100644
--- a/gcc/testsuite/gcc.dg/spellcheck-identifiers.c
+++ b/gcc/testsuite/gcc.dg/spellcheck-identifiers.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-function-declaration -fdiagnostics-show-caret" } */
+/* { dg-options "-fpermissive -fdiagnostics-show-caret" } */
 
 typedef struct GtkWidget { int dummy; } GtkWidget;
 
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/ld1sh_gather_1.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/ld1sh_gather_1.c
index 91f37f6a53d..c9f49b6e73d 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/ld1sh_gather_1.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/ld1sh_gather_1.c
@@ -11,7 +11,7 @@ f1 (svbool_t pg, short *s16_ptr, unsigned short *u16_ptr,
     svint32_t s32, svuint32_t u32, svfloat32_t f32,
     svint64_t s64, svuint64_t u64, svfloat64_t f64, struct s s)
 {
-  svld1sh_gather_index (pg, s16_ptr, s32); /* { dg-warning {implicit declaration of function 'svld1sh_gather_index'; did you mean 'svld1_gather_index'} } */
+  svld1sh_gather_index (pg, s16_ptr, s32); /* { dg-error {implicit declaration of function 'svld1sh_gather_index'; did you mean 'svld1_gather_index'} } */
   svld1sh_gather_index_u32 (pg, s16_ptr); /* { dg-error {too few arguments to function 'svld1sh_gather_index_u32'} } */
   svld1sh_gather_index_u32 (pg, s16_ptr, s32, 0); /* { dg-error {too many arguments to function 'svld1sh_gather_index_u32'} } */
   svld1sh_gather_index_u32 (pg, u16_ptr, s32); /* { dg-warning {pointer targets in passing argument 2 of 'svld1sh_gather_s32index_u32' differ in signedness} } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_index_1.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_index_1.c
index 91f37f6a53d..c9f49b6e73d 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_index_1.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_index_1.c
@@ -11,7 +11,7 @@ f1 (svbool_t pg, short *s16_ptr, unsigned short *u16_ptr,
     svint32_t s32, svuint32_t u32, svfloat32_t f32,
     svint64_t s64, svuint64_t u64, svfloat64_t f64, struct s s)
 {
-  svld1sh_gather_index (pg, s16_ptr, s32); /* { dg-warning {implicit declaration of function 'svld1sh_gather_index'; did you mean 'svld1_gather_index'} } */
+  svld1sh_gather_index (pg, s16_ptr, s32); /* { dg-error {implicit declaration of function 'svld1sh_gather_index'; did you mean 'svld1_gather_index'} } */
   svld1sh_gather_index_u32 (pg, s16_ptr); /* { dg-error {too few arguments to function 'svld1sh_gather_index_u32'} } */
   svld1sh_gather_index_u32 (pg, s16_ptr, s32, 0); /* { dg-error {too many arguments to function 'svld1sh_gather_index_u32'} } */
   svld1sh_gather_index_u32 (pg, u16_ptr, s32); /* { dg-warning {pointer targets in passing argument 2 of 'svld1sh_gather_s32index_u32' differ in signedness} } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_index_restricted_1.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_index_restricted_1.c
index c47e5411c20..a2dcf9a041b 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_index_restricted_1.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_index_restricted_1.c
@@ -13,7 +13,7 @@ f1 (svbool_t pg, short *s16_ptr, unsigned short *u16_ptr,
     svint32_t s32, svuint32_t u32, svfloat32_t f32,
     svint64_t s64, svuint64_t u64, svfloat64_t f64, struct s s)
 {
-  svldnt1sh_gather_index (pg, s16_ptr, s64); /* { dg-warning {implicit declaration of function 'svldnt1sh_gather_index'; did you mean 'svldnt1_gather_index'} } */
+  svldnt1sh_gather_index (pg, s16_ptr, s64); /* { dg-error {implicit declaration of function 'svldnt1sh_gather_index'; did you mean 'svldnt1_gather_index'} } */
   svldnt1sh_gather_index_u64 (pg, s16_ptr); /* { dg-error {too few arguments to function 'svldnt1sh_gather_index_u64'} } */
   svldnt1sh_gather_index_u64 (pg, s16_ptr, s64, 0); /* { dg-error {too many arguments to function 'svldnt1sh_gather_index_u64'} } */
   svldnt1sh_gather_index_u64 (pg, u16_ptr, s64); /* { dg-warning {pointer targets in passing argument 2 of 'svldnt1sh_gather_s64index_u64' differ in signedness} } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_1.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_1.c
index dae4d0ce120..cd849f89941 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_1.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_1.c
@@ -11,7 +11,7 @@ f1 (svbool_t pg, signed char *s8_ptr, short *s16_ptr,
     svint32_t s32, svuint32_t u32, svfloat32_t f32,
     svint64_t s64, svuint64_t u64, svfloat64_t f64, struct s s)
 {
-  svld1sb_gather_offset (pg, s8_ptr, s32); /* { dg-warning {implicit declaration of function 'svld1sb_gather_offset'; did you mean 'svld1_gather_offset'} } */
+  svld1sb_gather_offset (pg, s8_ptr, s32); /* { dg-error {implicit declaration of function 'svld1sb_gather_offset'; did you mean 'svld1_gather_offset'} } */
   svld1sb_gather_offset_s32 (pg, s8_ptr); /* { dg-error {too few arguments to function 'svld1sb_gather_offset_s32'} } */
   svld1sb_gather_offset_s32 (pg, s8_ptr, s32, 0); /* { dg-error {too many arguments to function 'svld1sb_gather_offset_s32'} } */
   svld1sb_gather_offset_s32 (pg, s16_ptr, s32); /* { dg-warning {passing argument 2 of 'svld1sb_gather_s32offset_s32' from incompatible pointer type} } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_2.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_2.c
index 1bc66977cdf..850eecf99f6 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_2.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_2.c
@@ -11,7 +11,7 @@ f1 (svbool_t pg, signed char *s8_ptr, short *s16_ptr,
     svint32_t s32, svuint32_t u32, svfloat32_t f32,
     svint64_t s64, svuint64_t u64, svfloat64_t f64, struct s s)
 {
-  svld1sb_gather_offset (pg, s8_ptr, s32); /* { dg-warning {implicit declaration of function 'svld1sb_gather_offset'; did you mean 'svld1_gather_offset'} } */
+  svld1sb_gather_offset (pg, s8_ptr, s32); /* { dg-error {implicit declaration of function 'svld1sb_gather_offset'; did you mean 'svld1_gather_offset'} } */
   svld1sb_gather_offset_u32 (pg, s8_ptr); /* { dg-error {too few arguments to function 'svld1sb_gather_offset_u32'} } */
   svld1sb_gather_offset_u32 (pg, s8_ptr, s32, 0); /* { dg-error {too many arguments to function 'svld1sb_gather_offset_u32'} } */
   svld1sb_gather_offset_u32 (pg, s16_ptr, s32); /* { dg-warning {passing argument 2 of 'svld1sb_gather_s32offset_u32' from incompatible pointer type} } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_3.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_3.c
index 6522889dbe7..93a728593f9 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_3.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_3.c
@@ -11,7 +11,7 @@ f1 (svbool_t pg, signed char *s8_ptr, short *s16_ptr,
     svint32_t s32, svuint32_t u32, svfloat32_t f32,
     svint64_t s64, svuint64_t u64, svfloat64_t f64, struct s s)
 {
-  svld1sb_gather_offset (pg, s8_ptr, s64); /* { dg-warning {implicit declaration of function 'svld1sb_gather_offset'; did you mean 'svld1_gather_offset'} } */
+  svld1sb_gather_offset (pg, s8_ptr, s64); /* { dg-error {implicit declaration of function 'svld1sb_gather_offset'; did you mean 'svld1_gather_offset'} } */
   svld1sb_gather_offset_s64 (pg, s8_ptr); /* { dg-error {too few arguments to function 'svld1sb_gather_offset_s64'} } */
   svld1sb_gather_offset_s64 (pg, s8_ptr, s64, 0); /* { dg-error {too many arguments to function 'svld1sb_gather_offset_s64'} } */
   svld1sb_gather_offset_s64 (pg, s16_ptr, s64); /* { dg-warning {passing argument 2 of 'svld1sb_gather_s64offset_s64' from incompatible pointer type} } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_4.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_4.c
index 02562198909..d54dc8eafab 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_4.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_4.c
@@ -11,7 +11,7 @@ f1 (svbool_t pg, signed char *s8_ptr, short *s16_ptr,
     svint32_t s32, svuint32_t u32, svfloat32_t f32,
     svint64_t s64, svuint64_t u64, svfloat64_t f64, struct s s)
 {
-  svld1sb_gather_offset (pg, s8_ptr, s64); /* { dg-warning {implicit declaration of function 'svld1sb_gather_offset'; did you mean 'svld1_gather_offset'} } */
+  svld1sb_gather_offset (pg, s8_ptr, s64); /* { dg-error {implicit declaration of function 'svld1sb_gather_offset'; did you mean 'svld1_gather_offset'} } */
   svld1sb_gather_offset_u64 (pg, s8_ptr); /* { dg-error {too few arguments to function 'svld1sb_gather_offset_u64'} } */
   svld1sb_gather_offset_u64 (pg, s8_ptr, s64, 0); /* { dg-error {too many arguments to function 'svld1sb_gather_offset_u64'} } */
   svld1sb_gather_offset_u64 (pg, s16_ptr, s64); /* { dg-warning {passing argument 2 of 'svld1sb_gather_s64offset_u64' from incompatible pointer type} } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_5.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_5.c
index 8d57aa020ea..3b521d5c141 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_5.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_5.c
@@ -11,7 +11,7 @@ f1 (svbool_t pg, unsigned char *s8_ptr, unsigned short *s16_ptr,
     svint32_t s32, svuint32_t u32, svfloat32_t f32,
     svint64_t s64, svuint64_t u64, svfloat64_t f64, struct s s)
 {
-  svld1ub_gather_offset (pg, s8_ptr, s32); /* { dg-warning {implicit declaration of function 'svld1ub_gather_offset'; did you mean 'svld1_gather_offset'} } */
+  svld1ub_gather_offset (pg, s8_ptr, s32); /* { dg-error {implicit declaration of function 'svld1ub_gather_offset'; did you mean 'svld1_gather_offset'} } */
   svld1ub_gather_offset_s32 (pg, s8_ptr); /* { dg-error {too few arguments to function 'svld1ub_gather_offset_s32'} } */
   svld1ub_gather_offset_s32 (pg, s8_ptr, s32, 0); /* { dg-error {too many arguments to function 'svld1ub_gather_offset_s32'} } */
   svld1ub_gather_offset_s32 (pg, s16_ptr, s32); /* { dg-warning {passing argument 2 of 'svld1ub_gather_s32offset_s32' from incompatible pointer type} } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_1.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_1.c
index 353fec2d39d..96d8ad55074 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_1.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_1.c
@@ -13,7 +13,7 @@ f1 (svbool_t pg, signed char *s8_ptr, short *s16_ptr,
     svint32_t s32, svuint32_t u32, svfloat32_t f32,
     svint64_t s64, svuint64_t u64, svfloat64_t f64, struct s s)
 {
-  svldnt1sb_gather_offset (pg, s8_ptr, s32); /* { dg-warning {implicit declaration of function 'svldnt1sb_gather_offset'; did you mean 'svldnt1_gather_offset'} } */
+  svldnt1sb_gather_offset (pg, s8_ptr, s32); /* { dg-error {implicit declaration of function 'svldnt1sb_gather_offset'; did you mean 'svldnt1_gather_offset'} } */
   svldnt1sb_gather_offset_s32 (pg, s8_ptr); /* { dg-error {too few arguments to function 'svldnt1sb_gather_offset_s32'} } */
   svldnt1sb_gather_offset_s32 (pg, s8_ptr, u32, 0); /* { dg-error {too many arguments to function 'svldnt1sb_gather_offset_s32'} } */
   svldnt1sb_gather_offset_s32 (pg, s16_ptr, u32); /* { dg-warning {passing argument 2 of 'svldnt1sb_gather_u32offset_s32' from incompatible pointer type} } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_2.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_2.c
index e22b3dd8fea..25ce7268a1e 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_2.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_2.c
@@ -13,7 +13,7 @@ f1 (svbool_t pg, signed char *s8_ptr, short *s16_ptr,
     svint32_t s32, svuint32_t u32, svfloat32_t f32,
     svint64_t s64, svuint64_t u64, svfloat64_t f64, struct s s)
 {
-  svldnt1sb_gather_offset (pg, s8_ptr, s32); /* { dg-warning {implicit declaration of function 'svldnt1sb_gather_offset'; did you mean 'svldnt1_gather_offset'} } */
+  svldnt1sb_gather_offset (pg, s8_ptr, s32); /* { dg-error {implicit declaration of function 'svldnt1sb_gather_offset'; did you mean 'svldnt1_gather_offset'} } */
   svldnt1sb_gather_offset_u32 (pg, s8_ptr); /* { dg-error {too few arguments to function 'svldnt1sb_gather_offset_u32'} } */
   svldnt1sb_gather_offset_u32 (pg, s8_ptr, u32, 0); /* { dg-error {too many arguments to function 'svldnt1sb_gather_offset_u32'} } */
   svldnt1sb_gather_offset_u32 (pg, s16_ptr, u32); /* { dg-warning {passing argument 2 of 'svldnt1sb_gather_u32offset_u32' from incompatible pointer type} } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_3.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_3.c
index 73b5715c368..04465f251b1 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_3.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_3.c
@@ -13,7 +13,7 @@ f1 (svbool_t pg, signed char *s8_ptr, short *s16_ptr,
     svint32_t s32, svuint32_t u32, svfloat32_t f32,
     svint64_t s64, svuint64_t u64, svfloat64_t f64, struct s s)
 {
-  svldnt1sb_gather_offset (pg, s8_ptr, s64); /* { dg-warning {implicit declaration of function 'svldnt1sb_gather_offset'; did you mean 'svldnt1_gather_offset'} } */
+  svldnt1sb_gather_offset (pg, s8_ptr, s64); /* { dg-error {implicit declaration of function 'svldnt1sb_gather_offset'; did you mean 'svldnt1_gather_offset'} } */
   svldnt1sb_gather_offset_s64 (pg, s8_ptr); /* { dg-error {too few arguments to function 'svldnt1sb_gather_offset_s64'} } */
   svldnt1sb_gather_offset_s64 (pg, s8_ptr, s64, 0); /* { dg-error {too many arguments to function 'svldnt1sb_gather_offset_s64'} } */
   svldnt1sb_gather_offset_s64 (pg, s16_ptr, s64); /* { dg-warning {passing argument 2 of 'svldnt1sb_gather_s64offset_s64' from incompatible pointer type} } */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_4.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_4.c
index e2ceb18bc42..479be66996d 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_4.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/load_ext_gather_offset_restricted_4.c
@@ -13,7 +13,7 @@ f1 (svbool_t pg, signed char *s8_ptr, short *s16_ptr,
     svint32_t s32, svuint32_t u32, svfloat32_t f32,
     svint64_t s64, svuint64_t u64, svfloat64_t f64, struct s s)
 {
-  svldnt1sb_gather_offset (pg, s8_ptr, s64); /* { dg-warning {implicit declaration of function 'svldnt1sb_gather_offset'; did you mean 'svldnt1_gather_offset'} } */
+  svldnt1sb_gather_offset (pg, s8_ptr, s64); /* { dg-error {implicit declaration of function 'svldnt1sb_gather_offset'; did you mean 'svldnt1_gather_offset'} } */
   svldnt1sb_gather_offset_u64 (pg, s8_ptr); /* { dg-error {too few arguments to function 'svldnt1sb_gather_offset_u64'} } */
   svldnt1sb_gather_offset_u64 (pg, s8_ptr, s64, 0); /* { dg-error {too many arguments to function 'svldnt1sb_gather_offset_u64'} } */
   svldnt1sb_gather_offset_u64 (pg, s16_ptr, s64); /* { dg-warning {passing argument 2 of 'svldnt1sb_gather_s64offset_u64' from incompatible pointer type} } */
