c: Add C2Y N3370 - Case range expressions support [PR117021]

The following patch adds the C2Y N3370 paper support.
We had the case ranges as a GNU extension for decades, so this patch
simply:
1) adds different diagnostics when it is used in C (depending on flag_isoc2y
   and pedantic and warn_c23_c2y_compat)
2) emits a pedwarn in C if in a range conversion changes the value of
   the low or high bounds and in that case doesn't emit -Woverflow and
   similar warnings anymore if the pedwarn has been diagnosed
3) changes the handling of empty ranges both in C and C++; previously
   we just warned but let the values be still looked up in the splay
   tree/entered into it (and let only gimplification throw away those
   empty cases), so e.g. case -6 ... -8: break; case -6: break;
   complained about duplicate case label.  But that actually isn't
   duplicate case label, case -6 ... -8: stands for nothing at all
   and that is how it is treated later on (thrown away)

2024-10-30  Jakub Jelinek  <jakub@redhat.com>

	PR c/117021
gcc/c-family/
	* c-common.cc (c_add_case_label): Emit different diagnostics for C
	on case ranges.  Diagnose for C using pedwarn conversions of range
	expressions changing value and don't emit further conversion
	diagnostics if the pedwarn has been diagnosed.  For empty ranges
	bail out after emitting warning, don't add anything into splay
	trees nor add a CASE_LABEL_EXPR.
gcc/testsuite/
	* gcc.dg/switch-6.c: Expect different diagnostics.  Add -std=gnu23
	to dg-options.
	* gcc.dg/switch-7.c: Expect different diagnostics.  Add -std=c23
	to dg-options.
	* gcc.dg/gnu23-switch-1.c: New test.
	* gcc.dg/gnu23-switch-2.c: New test.
	* gcc.dg/c23-switch-1.c: New test.
	* gcc.dg/c2y-switch-1.c: New test.
	* gcc.dg/c2y-switch-2.c: New test.
	* gcc.dg/c2y-switch-3.c: New test.

9 files changed, 565 insertions, 7 deletions

diff --git a/gcc/c-family/c-common.cc b/gcc/c-family/c-common.cc
index f7feb21..06be2a3 100644
--- a/gcc/c-family/c-common.cc
+++ b/gcc/c-family/c-common.cc
@@ -5186,13 +5186,41 @@ c_add_case_label (location_t loc, splay_tree cases, tree cond,
 
   /* Case ranges are a GNU extension.  */
   if (high_value)
-    pedwarn (loc, OPT_Wpedantic,
-	     "range expressions in switch statements are non-standard");
+    {
+      if (c_dialect_cxx ())
+	pedwarn (loc, OPT_Wpedantic,
+		 "range expressions in switch statements are non-standard");
+      else if (warn_c23_c2y_compat > 0)
+	{
+	  if (pedantic && !flag_isoc2y)
+	    pedwarn (loc, OPT_Wc23_c2y_compat,
+		     "ISO C does not support range expressions in switch "
+		     "statements before C2Y");
+	  else
+	    warning_at (loc, OPT_Wc23_c2y_compat,
+			"ISO C does not support range expressions in switch "
+			"statements before C2Y");
+	}
+      else if (warn_c23_c2y_compat && pedantic && !flag_isoc2y)
+	pedwarn (loc, OPT_Wpedantic,
+		 "ISO C does not support range expressions in switch "
+		 "statements before C2Y");
+    }
 
   type = TREE_TYPE (cond);
   if (low_value)
     {
       low_value = check_case_value (loc, low_value);
+      tree tem = NULL_TREE;
+      if (high_value
+	  && !c_dialect_cxx ()
+	  && low_value != error_mark_node
+	  && !int_fits_type_p (low_value, type)
+	  && pedwarn (loc, OPT_Wpedantic,
+		      "conversion of %qE to %qT in range expression changes "
+		      "value to %qE", low_value, type,
+		      (tem = fold_convert (type, low_value))))
+	low_value = tem;
       low_value = convert_and_check (loc, type, low_value);
       low_value = fold (low_value);
       if (low_value == error_mark_node)
@@ -5201,6 +5229,15 @@ c_add_case_label (location_t loc, splay_tree cases, tree cond,
   if (high_value)
     {
       high_value = check_case_value (loc, high_value);
+      tree tem = NULL_TREE;
+      if (!c_dialect_cxx ()
+	  && high_value != error_mark_node
+	  && !int_fits_type_p (high_value, type)
+	  && pedwarn (loc, OPT_Wpedantic,
+		      "conversion of %qE to %qT in range expression changes "
+		      "value to %qE", high_value, type,
+		      (tem = fold_convert (type, high_value))))
+	high_value = tem;
       high_value = convert_and_check (loc, type, high_value);
       high_value = fold (high_value);
       if (high_value == error_mark_node)
@@ -5215,7 +5252,10 @@ c_add_case_label (location_t loc, splay_tree cases, tree cond,
       if (tree_int_cst_equal (low_value, high_value))
 	high_value = NULL_TREE;
       else if (!tree_int_cst_lt (low_value, high_value))
-	warning_at (loc, 0, "empty range specified");
+	{
+	  warning_at (loc, 0, "empty range specified");
+	  goto error_out;
+	}
     }
 
   /* Look up the LOW_VALUE in the table of case labels we already
diff --git a/gcc/testsuite/gcc.dg/c23-switch-1.c b/gcc/testsuite/gcc.dg/c23-switch-1.c
new file mode 100644
index 0000000..c47dc51
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c23-switch-1.c
@@ -0,0 +1,100 @@
+/* C2Y N3370 - Case range expressions.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c23 -pedantic-errors -W -Wall" } */
+
+enum E { F = 10, G = 20 };
+
+void
+foo (unsigned x)
+{
+  switch (x)
+    {
+    case -1:
+      break;
+    case ~0U + 1ULL:			/* { dg-warning "conversion from 'long long unsigned int' to 'unsigned int' changes value from '\[0-9]*' to '0'" } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+bar (unsigned x)
+{
+  switch (x)
+    {
+    case -2 ... -1:			/* { dg-error "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-error "conversion of '-2' to 'unsigned int' in range expression changes value to '\[0-9]*'" "" { target *-*-* } .-1 } */
+					/* { dg-error "conversion of '-1' to 'unsigned int' in range expression changes value to '\[0-9]*'" "" { target *-*-* } .-2 } */
+      break;
+    case ~0U + 1ULL ... ~0U + 2ULL:	/* { dg-error "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-error "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '0'" "" { target *-*-* } .-1 } */
+					/* { dg-error "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '1'" "" { target *-*-* } .-2 } */
+      break;
+    case 70 ... 70:			/* { dg-error "ISO C does not support range expressions in switch statements before C2Y" } */
+      break;
+    case 80 ... 78:			/* { dg-error "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    case -4 ... -4:			/* { dg-error "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-error "conversion of '-4' to 'unsigned int' in range expression changes value to '\[0-9]*'" "" { target *-*-* } .-1 } */
+      break;
+    case ~0U + 6ULL ... ~0U + 6ULL:	/* { dg-error "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-error "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '5'" "" { target *-*-* } .-1 } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+baz (unsigned char x)
+{
+  switch (x)
+    {
+    case -32 ... -30:			/* { dg-error "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "case label value is less than minimum value for type" "" { target *-*-* } .-1 } */
+      break;
+    case -31:				/* { dg-error "duplicate case value" } */
+      break;
+    case -42:				/* { dg-warning "case label value is less than minimum value for type" } */
+      break;
+    case -43 ... -41:			/* { dg-error "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-error "duplicate \\\(or overlapping\\\) case value" "" { target *-*-* } .-1 } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+qux (int x)
+{
+  switch (x)
+    {
+    case -6 ... -8:			/* { dg-error "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    case -6:
+      break;
+    case -7:
+      break;
+    case -8:
+      break;
+    case F...G:				/* { dg-error "ISO C does not support range expressions in switch statements before C2Y" } */
+      break;
+    case -10:
+      break;
+    case -10 ... -11:			/* { dg-error "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    case -14 ... -15:			/* { dg-error "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    case -14 ... -15:			/* { dg-error "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    default:
+      break;
+    }
+}
diff --git a/gcc/testsuite/gcc.dg/c2y-switch-1.c b/gcc/testsuite/gcc.dg/c2y-switch-1.c
new file mode 100644
index 0000000..d3ef5c3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c2y-switch-1.c
@@ -0,0 +1,89 @@
+/* C2Y N3370 - Case range expressions.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c2y -pedantic -W -Wall" } */
+
+enum E { F = 10, G = 20 };
+
+void
+foo (unsigned x)
+{
+  switch (x)
+    {
+    case -1:
+      break;
+    case ~0U + 1ULL:			/* { dg-warning "conversion from 'long long unsigned int' to 'unsigned int' changes value from '\[0-9]*' to '0'" } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+bar (unsigned x)
+{
+  switch (x)
+    {
+    case -2 ... -1:			/* { dg-warning "conversion of '-2' to 'unsigned int' in range expression changes value to '\[0-9]*'" } */
+					/* { dg-warning "conversion of '-1' to 'unsigned int' in range expression changes value to '\[0-9]*'" "" { target *-*-* } .-1 } */
+      break;
+    case ~0U + 1ULL ... ~0U + 2ULL:	/* { dg-warning "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '0'" } */
+					/* { dg-warning "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '1'" "" { target *-*-* } .-1 } */
+      break;
+    case 70 ... 70:
+      break;
+    case 80 ... 78:			/* { dg-warning "empty range specified" } */
+      break;
+    case -4 ... -4:			/* { dg-warning "conversion of '-4' to 'unsigned int' in range expression changes value to '\[0-9]*'" } */
+      break;
+    case ~0U + 6ULL ... ~0U + 6ULL:	/* { dg-warning "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '5'" } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+baz (unsigned char x)
+{
+  switch (x)
+    {
+    case -32 ... -30:			/* { dg-warning "case label value is less than minimum value for type" } */
+      break;
+    case -31:				/* { dg-error "duplicate case value" } */
+      break;
+    case -42:				/* { dg-warning "case label value is less than minimum value for type" } */
+      break;
+    case -43 ... -41:			/* { dg-error "duplicate \\\(or overlapping\\\) case value" } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+qux (int x)
+{
+  switch (x)
+    {
+    case -6 ... -8:			/* { dg-warning "empty range specified" } */
+      break;
+    case -6:
+      break;
+    case -7:
+      break;
+    case -8:
+      break;
+    case F...G:
+      break;
+    case -10:
+      break;
+    case -10 ... -11:			/* { dg-warning "empty range specified" } */
+      break;
+    case -14 ... -15:			/* { dg-warning "empty range specified" } */
+      break;
+    case -14 ... -15:			/* { dg-warning "empty range specified" } */
+      break;
+    default:
+      break;
+    }
+}
diff --git a/gcc/testsuite/gcc.dg/c2y-switch-2.c b/gcc/testsuite/gcc.dg/c2y-switch-2.c
new file mode 100644
index 0000000..9ef4d40
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c2y-switch-2.c
@@ -0,0 +1,100 @@
+/* C2Y N3370 - Case range expressions.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c2y -pedantic -W -Wall -Wc23-c2y-compat" } */
+
+enum E { F = 10, G = 20 };
+
+void
+foo (unsigned x)
+{
+  switch (x)
+    {
+    case -1:
+      break;
+    case ~0U + 1ULL:			/* { dg-warning "conversion from 'long long unsigned int' to 'unsigned int' changes value from '\[0-9]*' to '0'" } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+bar (unsigned x)
+{
+  switch (x)
+    {
+    case -2 ... -1:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "conversion of '-2' to 'unsigned int' in range expression changes value to '\[0-9]*'" "" { target *-*-* } .-1 } */
+					/* { dg-warning "conversion of '-1' to 'unsigned int' in range expression changes value to '\[0-9]*'" "" { target *-*-* } .-2 } */
+      break;
+    case ~0U + 1ULL ... ~0U + 2ULL:	/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '0'" "" { target *-*-* } .-1 } */
+					/* { dg-warning "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '1'" "" { target *-*-* } .-2 } */
+      break;
+    case 70 ... 70:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+      break;
+    case 80 ... 78:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    case -4 ... -4:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "conversion of '-4' to 'unsigned int' in range expression changes value to '\[0-9]*'" "" { target *-*-* } .-1 } */
+      break;
+    case ~0U + 6ULL ... ~0U + 6ULL:	/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '5'" "" { target *-*-* } .-1 } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+baz (unsigned char x)
+{
+  switch (x)
+    {
+    case -32 ... -30:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "case label value is less than minimum value for type" "" { target *-*-* } .-1 } */
+      break;
+    case -31:				/* { dg-error "duplicate case value" } */
+      break;
+    case -42:				/* { dg-warning "case label value is less than minimum value for type" } */
+      break;
+    case -43 ... -41:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-error "duplicate \\\(or overlapping\\\) case value" "" { target *-*-* } .-1 } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+qux (int x)
+{
+  switch (x)
+    {
+    case -6 ... -8:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    case -6:
+      break;
+    case -7:
+      break;
+    case -8:
+      break;
+    case F...G:				/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+      break;
+    case -10:
+      break;
+    case -10 ... -11:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    case -14 ... -15:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    case -14 ... -15:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    default:
+      break;
+    }
+}
diff --git a/gcc/testsuite/gcc.dg/c2y-switch-3.c b/gcc/testsuite/gcc.dg/c2y-switch-3.c
new file mode 100644
index 0000000..3cb143a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c2y-switch-3.c
@@ -0,0 +1,40 @@
+/* C2Y N3370 - Case range expressions.  */
+/* { dg-do run } */
+/* { dg-options "-std=c2y -pedantic-errors" } */
+
+extern void abort ();
+
+void
+foo (int x)
+{
+  switch (x)
+    {
+    case -42 ... 42:
+      if (x < -42 || x > 42)
+        abort ();
+      break;
+    case 43 ... 43:
+      if (x != 43)
+        abort ();
+      break;
+    case 44:
+      if (x != 44)
+        abort ();
+      break;
+    case 45 ... 46:
+      if (x < 45 || x > 46)
+        abort ();
+      break;
+    default:
+      if (x >= -42 && x <= 46)
+        abort ();
+      break;
+    }
+}
+
+int
+main ()
+{
+  for (int i = -44; i <= 48; ++i)
+    foo (i);
+}
diff --git a/gcc/testsuite/gcc.dg/gnu23-switch-1.c b/gcc/testsuite/gcc.dg/gnu23-switch-1.c
new file mode 100644
index 0000000..57c3576
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gnu23-switch-1.c
@@ -0,0 +1,100 @@
+/* C2Y N3370 - Case range expressions.  */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu23 -pedantic -W -Wall" } */
+
+enum E { F = 10, G = 20 };
+
+void
+foo (unsigned x)
+{
+  switch (x)
+    {
+    case -1:
+      break;
+    case ~0U + 1ULL:			/* { dg-warning "conversion from 'long long unsigned int' to 'unsigned int' changes value from '\[0-9]*' to '0'" } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+bar (unsigned x)
+{
+  switch (x)
+    {
+    case -2 ... -1:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "conversion of '-2' to 'unsigned int' in range expression changes value to '\[0-9]*'" "" { target *-*-* } .-1 } */
+					/* { dg-warning "conversion of '-1' to 'unsigned int' in range expression changes value to '\[0-9]*'" "" { target *-*-* } .-2 } */
+      break;
+    case ~0U + 1ULL ... ~0U + 2ULL:	/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '0'" "" { target *-*-* } .-1 } */
+					/* { dg-warning "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '1'" "" { target *-*-* } .-2 } */
+      break;
+    case 70 ... 70:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+      break;
+    case 80 ... 78:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    case -4 ... -4:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "conversion of '-4' to 'unsigned int' in range expression changes value to '\[0-9]*'" "" { target *-*-* } .-1 } */
+      break;
+    case ~0U + 6ULL ... ~0U + 6ULL:	/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '5'" "" { target *-*-* } .-1 } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+baz (unsigned char x)
+{
+  switch (x)
+    {
+    case -32 ... -30:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "case label value is less than minimum value for type" "" { target *-*-* } .-1 } */
+      break;
+    case -31:				/* { dg-error "duplicate case value" } */
+      break;
+    case -42:				/* { dg-warning "case label value is less than minimum value for type" } */
+      break;
+    case -43 ... -41:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-error "duplicate \\\(or overlapping\\\) case value" "" { target *-*-* } .-1 } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+qux (int x)
+{
+  switch (x)
+    {
+    case -6 ... -8:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    case -6:
+      break;
+    case -7:
+      break;
+    case -8:
+      break;
+    case F...G:				/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+      break;
+    case -10:
+      break;
+    case -10 ... -11:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    case -14 ... -15:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    case -14 ... -15:			/* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
+					/* { dg-warning "empty range specified" "" { target *-*-* } .-1 } */
+      break;
+    default:
+      break;
+    }
+}
diff --git a/gcc/testsuite/gcc.dg/gnu23-switch-2.c b/gcc/testsuite/gcc.dg/gnu23-switch-2.c
new file mode 100644
index 0000000..47dd67b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gnu23-switch-2.c
@@ -0,0 +1,89 @@
+/* C2Y N3370 - Case range expressions.  */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu23 -pedantic -W -Wall -Wno-c23-c2y-compat" } */
+
+enum E { F = 10, G = 20 };
+
+void
+foo (unsigned x)
+{
+  switch (x)
+    {
+    case -1:
+      break;
+    case ~0U + 1ULL:			/* { dg-warning "conversion from 'long long unsigned int' to 'unsigned int' changes value from '\[0-9]*' to '0'" } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+bar (unsigned x)
+{
+  switch (x)
+    {
+    case -2 ... -1:			/* { dg-warning "conversion of '-2' to 'unsigned int' in range expression changes value to '\[0-9]*'" } */
+					/* { dg-warning "conversion of '-1' to 'unsigned int' in range expression changes value to '\[0-9]*'" "" { target *-*-* } .-1 } */
+      break;
+    case ~0U + 1ULL ... ~0U + 2ULL:	/* { dg-warning "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '0'" } */
+					/* { dg-warning "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '1'" "" { target *-*-* } .-1 } */
+      break;
+    case 70 ... 70:
+      break;
+    case 80 ... 78:			/* { dg-warning "empty range specified" } */
+      break;
+    case -4 ... -4:			/* { dg-warning "conversion of '-4' to 'unsigned int' in range expression changes value to '\[0-9]*'" } */
+      break;
+    case ~0U + 6ULL ... ~0U + 6ULL:	/* { dg-warning "conversion of '\[0-9]*' to 'unsigned int' in range expression changes value to '5'" } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+baz (unsigned char x)
+{
+  switch (x)
+    {
+    case -32 ... -30:			/* { dg-warning "case label value is less than minimum value for type" } */
+      break;
+    case -31:				/* { dg-error "duplicate case value" } */
+      break;
+    case -42:				/* { dg-warning "case label value is less than minimum value for type" } */
+      break;
+    case -43 ... -41:			/* { dg-error "duplicate \\\(or overlapping\\\) case value" } */
+      break;
+    default:
+      break;
+    }
+}
+
+void
+qux (int x)
+{
+  switch (x)
+    {
+    case -6 ... -8:			/* { dg-warning "empty range specified" } */
+      break;
+    case -6:
+      break;
+    case -7:
+      break;
+    case -8:
+      break;
+    case F...G:
+      break;
+    case -10:
+      break;
+    case -10 ... -11:			/* { dg-warning "empty range specified" } */
+      break;
+    case -14 ... -15:			/* { dg-warning "empty range specified" } */
+      break;
+    case -14 ... -15:			/* { dg-warning "empty range specified" } */
+      break;
+    default:
+      break;
+    }
+}
diff --git a/gcc/testsuite/gcc.dg/switch-6.c b/gcc/testsuite/gcc.dg/switch-6.c
index 25d1d96..24ff498 100644
--- a/gcc/testsuite/gcc.dg/switch-6.c
+++ b/gcc/testsuite/gcc.dg/switch-6.c
@@ -2,13 +2,13 @@
    for case ranges with -pedantic.  */
 /* Origin: Joseph Myers <joseph@codesourcery.com> */
 /* { dg-do compile } */
-/* { dg-options "-pedantic" } */
+/* { dg-options "-pedantic -std=gnu23" } */
 
 void
 f (int a)
 {
   switch (a)
     {
-    case 0 ... 0: ; /* { dg-warning "range expressions in switch statements are non-standard" } */
+    case 0 ... 0: ; /* { dg-warning "ISO C does not support range expressions in switch statements before C2Y" } */
     }
 }
diff --git a/gcc/testsuite/gcc.dg/switch-7.c b/gcc/testsuite/gcc.dg/switch-7.c
index 29cb825..05b1fb8 100644
--- a/gcc/testsuite/gcc.dg/switch-7.c
+++ b/gcc/testsuite/gcc.dg/switch-7.c
@@ -2,13 +2,13 @@
    for case ranges with -pedantic-errors.  */
 /* Origin: Joseph Myers <joseph@codesourcery.com> */
 /* { dg-do compile } */
-/* { dg-options "-pedantic-errors" } */
+/* { dg-options "-pedantic-errors -std=c23" } */
 
 void
 f (int a)
 {
   switch (a)
     {
-    case 0 ... 0: ; /* { dg-error "range expressions in switch statements are non-standard" } */
+    case 0 ... 0: ; /* { dg-error "ISO C does not support range expressions in switch statements before C2Y" } */
     }
 }