gdb: Use std::string_view instead of gdb::string_view

Given that GDB now requires a C++17, replace all uses of
gdb::string_view with std::string_view.

This change has mostly been done automatically:
- gdb::string_view -> std::string_view
- #include "gdbsupport/gdb_string_view.h" -> #include <string_view>

One things which got brought up during review is that gdb::stging_view
does support being built from "nullptr" while std::sting_view does not.
Two places are manually adjusted to account for this difference:
gdb/tui/tui-io.c:tui_getc_1 and
gdbsupport/format.h:format_piece::format_piece.

The above automatic change transformed
"gdb::to_string (const gdb::string_view &)" into
"gdb::to_string (const std::string_view &)".  The various direct users
of this function are now explicitly including
"gdbsupport/gdb_string_view.h".  A later patch will remove the users of
gdb::to_string.

The implementation and tests of gdb::string_view are unchanged, they will
be removed in a following patch.

Change-Id: Ibb806a7e9c79eb16a55c87c6e41ad396fecf0207
Approved-By: Tom Tromey <tom@tromey.com>
Approved-By: Pedro Alves <pedro@palves.net>

1 files changed, 9 insertions, 9 deletions

diff --git a/gdb/xcoffread.c b/gdb/xcoffread.c
index e6ecf2a..829fc1f 100644
--- a/gdb/xcoffread.c
+++ b/gdb/xcoffread.c
@@ -2500,7 +2500,7 @@ scan_xcoff_symtab (minimal_symbol_reader &reader,
 	    switch (p[1])
 	      {
 	      case 'S':
-		pst->add_psymbol (gdb::string_view (namestring,
+		pst->add_psymbol (std::string_view (namestring,
 						    p - namestring),
 				  true, VAR_DOMAIN, LOC_STATIC,
 				  SECT_OFF_DATA (objfile),
@@ -2513,7 +2513,7 @@ scan_xcoff_symtab (minimal_symbol_reader &reader,
 	      case 'G':
 		/* The addresses in these entries are reported to be
 		   wrong.  See the code that reads 'G's for symtabs.  */
-		pst->add_psymbol (gdb::string_view (namestring,
+		pst->add_psymbol (std::string_view (namestring,
 						    p - namestring),
 				  true, VAR_DOMAIN, LOC_STATIC,
 				  SECT_OFF_DATA (objfile),
@@ -2534,7 +2534,7 @@ scan_xcoff_symtab (minimal_symbol_reader &reader,
 		    || (p == namestring + 1
 			&& namestring[0] != ' '))
 		  {
-		    pst->add_psymbol (gdb::string_view (namestring,
+		    pst->add_psymbol (std::string_view (namestring,
 							p - namestring),
 				      true, STRUCT_DOMAIN, LOC_TYPEDEF, -1,
 				      psymbol_placement::STATIC,
@@ -2544,7 +2544,7 @@ scan_xcoff_symtab (minimal_symbol_reader &reader,
 		    if (p[2] == 't')
 		      {
 			/* Also a typedef with the same name.  */
-			pst->add_psymbol (gdb::string_view (namestring,
+			pst->add_psymbol (std::string_view (namestring,
 							    p - namestring),
 					  true, VAR_DOMAIN, LOC_TYPEDEF, -1,
 					  psymbol_placement::STATIC,
@@ -2559,7 +2559,7 @@ scan_xcoff_symtab (minimal_symbol_reader &reader,
 	      case 't':
 		if (p != namestring)	/* a name is there, not just :T...  */
 		  {
-		    pst->add_psymbol (gdb::string_view (namestring,
+		    pst->add_psymbol (std::string_view (namestring,
 							p - namestring),
 				      true, VAR_DOMAIN, LOC_TYPEDEF, -1,
 				      psymbol_placement::STATIC,
@@ -2624,7 +2624,7 @@ scan_xcoff_symtab (minimal_symbol_reader &reader,
 			  ;
 			/* Note that the value doesn't matter for
 			   enum constants in psymtabs, just in symtabs.  */
-			pst->add_psymbol (gdb::string_view (p, q - p), true,
+			pst->add_psymbol (std::string_view (p, q - p), true,
 					  VAR_DOMAIN, LOC_CONST, -1,
 					  psymbol_placement::STATIC,
 					  unrelocated_addr (0),
@@ -2644,7 +2644,7 @@ scan_xcoff_symtab (minimal_symbol_reader &reader,
 
 	      case 'c':
 		/* Constant, e.g. from "const" in Pascal.  */
-		pst->add_psymbol (gdb::string_view (namestring,
+		pst->add_psymbol (std::string_view (namestring,
 						    p - namestring),
 				  true, VAR_DOMAIN, LOC_CONST, -1,
 				  psymbol_placement::STATIC,
@@ -2659,7 +2659,7 @@ scan_xcoff_symtab (minimal_symbol_reader &reader,
 		    std::string name (namestring, (p - namestring));
 		    function_outside_compilation_unit_complaint (name.c_str ());
 		  }
-		pst->add_psymbol (gdb::string_view (namestring,
+		pst->add_psymbol (std::string_view (namestring,
 						    p - namestring),
 				  true, VAR_DOMAIN, LOC_BLOCK,
 				  SECT_OFF_TEXT (objfile),
@@ -2686,7 +2686,7 @@ scan_xcoff_symtab (minimal_symbol_reader &reader,
 		if (startswith (namestring, "@FIX"))
 		  continue;
 
-		pst->add_psymbol (gdb::string_view (namestring,
+		pst->add_psymbol (std::string_view (namestring,
 						    p - namestring),
 				  true, VAR_DOMAIN, LOC_BLOCK,
 				  SECT_OFF_TEXT (objfile),