Remove const char * support for asm constexpr

asm constexpr now only accepts the same string types as C++26 assert,
e.g. string_view and string. Adjust test suite and documentation.

gcc/cp/ChangeLog:

	* parser.cc (cp_parser_asm_string_expression): Remove support
	for const char * for asm constexpr.

gcc/ChangeLog:

	* doc/extend.texi: Use std::string_view in asm constexpr
	example.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp1z/constexpr-asm-1.C: Use std::std_string_view.
	* g++.dg/cpp1z/constexpr-asm-3.C: Dito.

4 files changed, 16 insertions, 18 deletions

diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index de5f048..98e8ca1 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -22852,13 +22852,6 @@ cp_parser_asm_string_expression (cp_parser *parser)
       tree string = cp_parser_constant_expression (parser);
       if (string != error_mark_node)
 	string = cxx_constant_value (string, tf_error);
-      if (TREE_CODE (string) == NOP_EXPR)
-	string = TREE_OPERAND (string, 0);
-      if (TREE_CODE (string) == ADDR_EXPR
-	  && TREE_CODE (TREE_OPERAND (string, 0)) == STRING_CST)
-	string = TREE_OPERAND (string, 0);
-      if (TREE_CODE (string) == VIEW_CONVERT_EXPR)
-	string = TREE_OPERAND (string, 0);
       cexpr_str cstr (string);
       if (!cstr.type_check (tok->location))
 	return error_mark_node;
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 17e26c5..ee3644a 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -10716,7 +10716,8 @@ message. Any string is converted to the character set of the source code.
 When this feature is available the @code{__GXX_CONSTEXPR_ASM__} cpp symbol is defined.
 
 @example
-constexpr const char *genfoo() @{ return "foo"; @}
+#include <string>
+constexpr std::string_view genfoo() @{ return "foo"; @}
 
 void function()
 @{
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-asm-1.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-asm-1.C
index 7cc6b37..311209a 100644
--- a/gcc/testsuite/g++.dg/cpp1z/constexpr-asm-1.C
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-asm-1.C
@@ -1,22 +1,24 @@
 /* { dg-do compile } */
-/* { dg-options "-std=gnu++11" } */
+/* { dg-options "-std=gnu++17" } */
 
-constexpr const char *genfoo ()
+#include <string>
+
+constexpr std::string_view genfoo ()
 {
   return "foo %1,%0";
 }
 
-constexpr const char *genoutput ()
+constexpr std::string_view genoutput ()
 {
   return "=r";
 }
 
-constexpr const char *geninput ()
+constexpr std::string_view geninput ()
 {
   return "r";
 }
 
-constexpr const char *genclobber ()
+constexpr std::string_view genclobber ()
 {
   return "memory";
 }
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-asm-3.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-asm-3.C
index d336318..ef8a35a 100644
--- a/gcc/testsuite/g++.dg/cpp1z/constexpr-asm-3.C
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-asm-3.C
@@ -1,22 +1,24 @@
 /* { dg-do compile } */
-/* { dg-options "-std=gnu++11" } */
+/* { dg-options "-std=gnu++17" } */
 
-constexpr const char *genfoo ()
+#include <string>
+
+constexpr std::string_view genfoo ()
 {
   return "foo %1,%0";
 }
 
-constexpr const char *genoutput ()
+constexpr std::string_view genoutput ()
 {
   return "=r";
 }
 
-constexpr const char *geninput ()
+constexpr std::string_view geninput ()
 {
   return "r";
 }
 
-constexpr const char *genclobber ()
+constexpr std::string_view genclobber ()
 {
   return "memory";
 }