Add C parser support for "restrict" and "_Atomic"

A user noticed that "watch -location" would fail with a "restrict"
pointer.  The issue here is that if the DWARF mentions "restrict", gdb
will put this into the type name -- but then the C parser will not be
able to parse this type.

This patch adds support for "restrict" and "_Atomic" to the C parser.
C++ doesn't have "restrict", but does have some GCC extensions.  The
type printer is changed to handle this difference as well, so that
watch expressions will work properly.

gdb/ChangeLog
2020-03-14  Tom Tromey  <tom@tromey.com>

	* c-typeprint.c (cp_type_print_method_args): Print "__restrict__"
	for C++.
	(c_type_print_modifier): Likewise.  Add "language" parameter.
	(c_type_print_varspec_prefix, c_type_print_base_struct_union)
	(c_type_print_base_1): Update.
	* type-stack.h (enum type_pieces) <tp_atomic, tp_restrict>: New
	constants.
	* type-stack.c (type_stack::insert): Handle tp_atomic and
	tp_restrict.
	(type_stack::follow_type_instance_flags): Likewise.
	(type_stack::follow_types): Likewise.  Merge type-following code.
	* c-exp.y (RESTRICT, ATOMIC): New tokens.
	(space_identifier, cv_with_space_id)
	(const_or_volatile_or_space_identifier_noopt)
	(const_or_volatile_or_space_identifier): Remove.
	(single_qualifier, qualifier_seq_noopt, qualifier_seq): New
	rules.
	(ptr_operator, typebase): Update.
	(enum token_flag) <FLAG_C>: New constant.
	(ident_tokens): Add "restrict", "__restrict__", "__restrict", and
	"_Atomic".
	(lex_one_token): Handle FLAG_C.

gdb/testsuite/ChangeLog
2020-03-14  Tom Tromey  <tom@tromey.com>

	* gdb.base/cvexpr.exp: Add test for _Atomic and restrict.

7 files changed, 133 insertions, 68 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 04db5e7..a0d9758 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,28 @@
+2020-03-14  Tom Tromey  <tom@tromey.com>
+
+	* c-typeprint.c (cp_type_print_method_args): Print "__restrict__"
+	for C++.
+	(c_type_print_modifier): Likewise.  Add "language" parameter.
+	(c_type_print_varspec_prefix, c_type_print_base_struct_union)
+	(c_type_print_base_1): Update.
+	* type-stack.h (enum type_pieces) <tp_atomic, tp_restrict>: New
+	constants.
+	* type-stack.c (type_stack::insert): Handle tp_atomic and
+	tp_restrict.
+	(type_stack::follow_type_instance_flags): Likewise.
+	(type_stack::follow_types): Likewise.  Merge type-following code.
+	* c-exp.y (RESTRICT, ATOMIC): New tokens.
+	(space_identifier, cv_with_space_id)
+	(const_or_volatile_or_space_identifier_noopt)
+	(const_or_volatile_or_space_identifier): Remove.
+	(single_qualifier, qualifier_seq_noopt, qualifier_seq): New
+	rules.
+	(ptr_operator, typebase): Update.
+	(enum token_flag) <FLAG_C>: New constant.
+	(ident_tokens): Add "restrict", "__restrict__", "__restrict", and
+	"_Atomic".
+	(lex_one_token): Handle FLAG_C.
+
 2020-03-14  Kamil Rytarowski  <n54@gmx.com>
 
 	* m68k-bsd-nat.c (fetch_registers): New variable lwp and pass
diff --git a/gdb/c-exp.y b/gdb/c-exp.y
index 3403a85..50a2eef 100644
--- a/gdb/c-exp.y
+++ b/gdb/c-exp.y
@@ -237,6 +237,7 @@ static void c_print_token (FILE *file, int type, YYSTYPE value);
 /* Special type cases, put in to allow the parser to distinguish different
    legal basetypes.  */
 %token SIGNED_KEYWORD LONG SHORT INT_KEYWORD CONST_KEYWORD VOLATILE_KEYWORD DOUBLE_KEYWORD
+%token RESTRICT ATOMIC
 
 %token <sval> DOLLAR_VARIABLE
 
@@ -1169,36 +1170,43 @@ variable:	name_not_typename
 			}
 	;
 
-space_identifier : '@' NAME
-		{
-		  cpstate->type_stack.insert (pstate,
-					      copy_name ($2.stoken).c_str ());
-		}
-	;
-
 const_or_volatile: const_or_volatile_noopt
 	|
 	;
 
-cv_with_space_id : const_or_volatile space_identifier const_or_volatile
+single_qualifier:
+		CONST_KEYWORD
+			{ cpstate->type_stack.insert (tp_const); }
+	| 	VOLATILE_KEYWORD
+			{ cpstate->type_stack.insert (tp_volatile); }
+	| 	ATOMIC
+			{ cpstate->type_stack.insert (tp_atomic); }
+	| 	RESTRICT
+			{ cpstate->type_stack.insert (tp_restrict); }
+	|	'@' NAME
+		{
+		  cpstate->type_stack.insert (pstate,
+					      copy_name ($2.stoken).c_str ());
+		}
 	;
 
-const_or_volatile_or_space_identifier_noopt: cv_with_space_id
-	| const_or_volatile_noopt
+qualifier_seq_noopt:
+		single_qualifier
+	| 	qualifier_seq single_qualifier
 	;
 
-const_or_volatile_or_space_identifier:
-		const_or_volatile_or_space_identifier_noopt
+qualifier_seq:
+		qualifier_seq_noopt
 	|
 	;
 
 ptr_operator:
 		ptr_operator '*'
 			{ cpstate->type_stack.insert (tp_pointer); }
-		const_or_volatile_or_space_identifier
+		qualifier_seq
 	|	'*'
 			{ cpstate->type_stack.insert (tp_pointer); }
-		const_or_volatile_or_space_identifier
+		qualifier_seq
 	|	'&'
 			{ cpstate->type_stack.insert (tp_reference); }
 	|	'&' ptr_operator
@@ -1472,9 +1480,9 @@ typebase
 			    (copy_name($2).c_str (), $4,
 			     pstate->expression_context_block);
 			}
-	| const_or_volatile_or_space_identifier_noopt typebase
+	|	qualifier_seq_noopt typebase
 			{ $$ = cpstate->type_stack.follow_types ($2); }
-	| typebase const_or_volatile_or_space_identifier_noopt
+	|	typebase qualifier_seq_noopt
 			{ $$ = cpstate->type_stack.follow_types ($1); }
 	;
 
@@ -2345,11 +2353,15 @@ enum token_flag
 
   FLAG_CXX = 1,
 
+  /* If this bit is set, the token is C-only.  */
+
+  FLAG_C = 2,
+
   /* If this bit is set, the token is conditional: if there is a
      symbol of the same name, then the token is a symbol; otherwise,
      the token is a keyword.  */
 
-  FLAG_SHADOW = 2
+  FLAG_SHADOW = 4
 };
 DEF_ENUM_FLAGS_TYPE (enum token_flag, token_flags);
 
@@ -2416,6 +2428,10 @@ static const struct token ident_tokens[] =
     {"union", UNION, OP_NULL, 0},
     {"short", SHORT, OP_NULL, 0},
     {"const", CONST_KEYWORD, OP_NULL, 0},
+    {"restrict", RESTRICT, OP_NULL, FLAG_C | FLAG_SHADOW},
+    {"__restrict__", RESTRICT, OP_NULL, 0},
+    {"__restrict", RESTRICT, OP_NULL, 0},
+    {"_Atomic", ATOMIC, OP_NULL, 0},
     {"enum", ENUM, OP_NULL, 0},
     {"long", LONG, OP_NULL, 0},
     {"true", TRUEKEYWORD, OP_NULL, FLAG_CXX},
@@ -2550,6 +2566,7 @@ lex_one_token (struct parser_state *par_state, bool *is_quoted_name)
 	if ((tokentab3[i].flags & FLAG_CXX) != 0
 	    && par_state->language ()->la_language != language_cplus)
 	  break;
+	gdb_assert ((tokentab3[i].flags & FLAG_C) == 0);
 
 	pstate->lexptr += 3;
 	yylval.opcode = tokentab3[i].opcode;
@@ -2563,6 +2580,7 @@ lex_one_token (struct parser_state *par_state, bool *is_quoted_name)
 	if ((tokentab2[i].flags & FLAG_CXX) != 0
 	    && par_state->language ()->la_language != language_cplus)
 	  break;
+	gdb_assert ((tokentab3[i].flags & FLAG_C) == 0);
 
 	pstate->lexptr += 2;
 	yylval.opcode = tokentab2[i].opcode;
@@ -2857,6 +2875,10 @@ lex_one_token (struct parser_state *par_state, bool *is_quoted_name)
 	if ((ident_tokens[i].flags & FLAG_CXX) != 0
 	    && par_state->language ()->la_language != language_cplus)
 	  break;
+	if ((ident_tokens[i].flags & FLAG_C) != 0
+	    && par_state->language ()->la_language != language_c
+	    && par_state->language ()->la_language != language_objc)
+	  break;
 
 	if ((ident_tokens[i].flags & FLAG_SHADOW) != 0)
 	  {
diff --git a/gdb/c-typeprint.c b/gdb/c-typeprint.c
index 1f27b56..50d0eaa 100644
--- a/gdb/c-typeprint.c
+++ b/gdb/c-typeprint.c
@@ -58,7 +58,7 @@ static void c_type_print_varspec_prefix (struct type *,
 /* Print "const", "volatile", or address space modifiers.  */
 static void c_type_print_modifier (struct type *,
 				   struct ui_file *,
-				   int, int);
+				   int, int, enum language);
 
 static void c_type_print_base_1 (struct type *type, struct ui_file *stream,
 				 int show, int level, enum language language,
@@ -337,7 +337,9 @@ cp_type_print_method_args (struct type *mtype, const char *prefix,
 	fprintf_filtered (stream, " volatile");
 
       if (TYPE_RESTRICT (domain))
-	fprintf_filtered (stream, " restrict");
+	fprintf_filtered (stream, (language == language_cplus
+				   ? " __restrict__"
+				   : " restrict"));
 
       if (TYPE_ATOMIC (domain))
 	fprintf_filtered (stream, " _Atomic");
@@ -383,7 +385,7 @@ c_type_print_varspec_prefix (struct type *type,
 				   stream, show, 1, 1, language, flags,
 				   podata);
       fprintf_filtered (stream, "*");
-      c_type_print_modifier (type, stream, 1, need_post_space);
+      c_type_print_modifier (type, stream, 1, need_post_space, language);
       break;
 
     case TYPE_CODE_MEMBERPTR:
@@ -420,7 +422,7 @@ c_type_print_varspec_prefix (struct type *type,
 				   stream, show, 1, 0, language, flags,
 				   podata);
       fprintf_filtered (stream, TYPE_CODE(type) == TYPE_CODE_REF ? "&" : "&&");
-      c_type_print_modifier (type, stream, 1, need_post_space);
+      c_type_print_modifier (type, stream, 1, need_post_space, language);
       break;
 
     case TYPE_CODE_METHOD:
@@ -481,7 +483,8 @@ c_type_print_varspec_prefix (struct type *type,
 
 static void
 c_type_print_modifier (struct type *type, struct ui_file *stream,
-		       int need_pre_space, int need_post_space)
+		       int need_pre_space, int need_post_space,
+		       enum language language)
 {
   int did_print_modifier = 0;
   const char *address_space_id;
@@ -509,7 +512,9 @@ c_type_print_modifier (struct type *type, struct ui_file *stream,
     {
       if (did_print_modifier || need_pre_space)
 	fprintf_filtered (stream, " ");
-      fprintf_filtered (stream, "restrict");
+      fprintf_filtered (stream, (language == language_cplus
+				 ? "__restrict__"
+				 : "restrict"));
       did_print_modifier = 1;
     }
 
@@ -1050,7 +1055,7 @@ c_type_print_base_struct_union (struct type *type, struct ui_file *stream,
       hash_holder.reset (local_flags.local_typedefs);
     }
 
-  c_type_print_modifier (type, stream, 0, 1);
+  c_type_print_modifier (type, stream, 0, 1, language);
   if (TYPE_CODE (type) == TYPE_CODE_UNION)
     fprintf_filtered (stream, "union ");
   else if (TYPE_DECLARED_CLASS (type))
@@ -1477,7 +1482,7 @@ c_type_print_base_1 (struct type *type, struct ui_file *stream,
   if (show <= 0
       && TYPE_NAME (type) != NULL)
     {
-      c_type_print_modifier (type, stream, 0, 1);
+      c_type_print_modifier (type, stream, 0, 1, language);
 
       /* If we have "typedef struct foo {. . .} bar;" do we want to
 	 print it as "struct foo" or as "bar"?  Pick the latter for
@@ -1542,7 +1547,7 @@ c_type_print_base_1 (struct type *type, struct ui_file *stream,
       break;
 
     case TYPE_CODE_ENUM:
-      c_type_print_modifier (type, stream, 0, 1);
+      c_type_print_modifier (type, stream, 0, 1, language);
       fprintf_filtered (stream, "enum ");
       if (TYPE_DECLARED_CLASS (type))
 	fprintf_filtered (stream, "class ");
@@ -1615,7 +1620,7 @@ c_type_print_base_1 (struct type *type, struct ui_file *stream,
 
 	local_flags.local_typedefs = NULL;
 
-	c_type_print_modifier (type, stream, 0, 1);
+	c_type_print_modifier (type, stream, 0, 1, language);
 	fprintf_filtered (stream, "flag ");
 	print_name_maybe_canonical (TYPE_NAME (type), flags, stream);
 	if (show > 0)
@@ -1689,7 +1694,7 @@ c_type_print_base_1 (struct type *type, struct ui_file *stream,
          type name, then complain.  */
       if (TYPE_NAME (type) != NULL)
 	{
-	  c_type_print_modifier (type, stream, 0, 1);
+	  c_type_print_modifier (type, stream, 0, 1, language);
 	  print_name_maybe_canonical (TYPE_NAME (type), flags, stream);
 	}
       else
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 07ed021..a3114d3 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2020-03-14  Tom Tromey  <tom@tromey.com>
+
+	* gdb.base/cvexpr.exp: Add test for _Atomic and restrict.
+
 2020-03-14  Tom de Vries  <tdevries@suse.de>
 
 	* gdb.mi/mi-fortran-modules.exp: Use exp_continue.
diff --git a/gdb/testsuite/gdb.base/cvexpr.exp b/gdb/testsuite/gdb.base/cvexpr.exp
index 92a073a7..d905198 100644
--- a/gdb/testsuite/gdb.base/cvexpr.exp
+++ b/gdb/testsuite/gdb.base/cvexpr.exp
@@ -509,3 +509,14 @@ foreach testspec $specs {
 	do_test $prefix $opts
     }
 }
+
+# These tests don't rely on the debug format.
+gdb_test "ptype _Atomic int" "type = _Atomic int"
+gdb_test "ptype int * restrict" "type = int \\* restrict"
+
+# C++ does not have "restrict".
+gdb_test_no_output "set lang c++"
+gdb_test "ptype int * restrict" "A syntax error in expression.*"
+
+# There is a GCC extension for __restrict__, though.
+gdb_test "ptype int * __restrict__" "type = int \\* __restrict__"
diff --git a/gdb/type-stack.c b/gdb/type-stack.c
index ab7e026..73b7d5a 100644
--- a/gdb/type-stack.c
+++ b/gdb/type-stack.c
@@ -33,12 +33,14 @@ type_stack::insert (enum type_pieces tp)
 
   gdb_assert (tp == tp_pointer || tp == tp_reference
 	      || tp == tp_rvalue_reference || tp == tp_const
-	      || tp == tp_volatile);
+	      || tp == tp_volatile || tp == tp_restrict
+	      || tp == tp_atomic);
 
   /* If there is anything on the stack (we know it will be a
      tp_pointer), insert the qualifier above it.  Otherwise, simply
      push this on the top of the stack.  */
-  if (!m_elements.empty () && (tp == tp_const || tp == tp_volatile))
+  if (!m_elements.empty () && (tp == tp_const || tp == tp_volatile
+			       || tp == tp_restrict))
     slot = 1;
   else
     slot = 0;
@@ -88,6 +90,12 @@ type_stack::follow_type_instance_flags ()
       case tp_volatile:
 	flags |= TYPE_INSTANCE_FLAG_VOLATILE;
 	break;
+      case tp_atomic:
+	flags |= TYPE_INSTANCE_FLAG_ATOMIC;
+	break;
+      case tp_restrict:
+	flags |= TYPE_INSTANCE_FLAG_RESTRICT;
+	break;
       default:
 	gdb_assert_not_reached ("unrecognized tp_ value in follow_types");
       }
@@ -102,6 +110,8 @@ type_stack::follow_types (struct type *follow_type)
   int make_const = 0;
   int make_volatile = 0;
   int make_addr_space = 0;
+  bool make_restrict = false;
+  bool make_atomic = false;
   int array_size;
 
   while (!done)
@@ -109,19 +119,7 @@ type_stack::follow_types (struct type *follow_type)
       {
       case tp_end:
 	done = 1;
-	if (make_const)
-	  follow_type = make_cv_type (make_const, 
-				      TYPE_VOLATILE (follow_type), 
-				      follow_type, 0);
-	if (make_volatile)
-	  follow_type = make_cv_type (TYPE_CONST (follow_type), 
-				      make_volatile, 
-				      follow_type, 0);
-	if (make_addr_space)
-	  follow_type = make_type_with_address_space (follow_type, 
-						      make_addr_space);
-	make_const = make_volatile = 0;
-	make_addr_space = 0;
+	goto process_qualifiers;
 	break;
       case tp_const:
 	make_const = 1;
@@ -132,41 +130,39 @@ type_stack::follow_types (struct type *follow_type)
       case tp_space_identifier:
 	make_addr_space = pop_int ();
 	break;
+      case tp_atomic:
+	make_atomic = true;
+	break;
+      case tp_restrict:
+	make_restrict = true;
+	break;
       case tp_pointer:
 	follow_type = lookup_pointer_type (follow_type);
+	goto process_qualifiers;
+      case tp_reference:
+	follow_type = lookup_lvalue_reference_type (follow_type);
+	goto process_qualifiers;
+      case tp_rvalue_reference:
+	follow_type = lookup_rvalue_reference_type (follow_type);
+      process_qualifiers:
 	if (make_const)
-	  follow_type = make_cv_type (make_const, 
-				      TYPE_VOLATILE (follow_type), 
+	  follow_type = make_cv_type (make_const,
+				      TYPE_VOLATILE (follow_type),
 				      follow_type, 0);
 	if (make_volatile)
-	  follow_type = make_cv_type (TYPE_CONST (follow_type), 
-				      make_volatile, 
+	  follow_type = make_cv_type (TYPE_CONST (follow_type),
+				      make_volatile,
 				      follow_type, 0);
 	if (make_addr_space)
-	  follow_type = make_type_with_address_space (follow_type, 
+	  follow_type = make_type_with_address_space (follow_type,
 						      make_addr_space);
+	if (make_restrict)
+	  follow_type = make_restrict_type (follow_type);
+	if (make_atomic)
+	  follow_type = make_atomic_type (follow_type);
 	make_const = make_volatile = 0;
 	make_addr_space = 0;
-	break;
-      case tp_reference:
-	 follow_type = lookup_lvalue_reference_type (follow_type);
-	 goto process_reference;
-	case tp_rvalue_reference:
-	 follow_type = lookup_rvalue_reference_type (follow_type);
-	process_reference:
-	 if (make_const)
-	   follow_type = make_cv_type (make_const,
-				       TYPE_VOLATILE (follow_type),
-				       follow_type, 0);
-	 if (make_volatile)
-	   follow_type = make_cv_type (TYPE_CONST (follow_type),
-				       make_volatile,
-				       follow_type, 0);
-	 if (make_addr_space)
-	   follow_type = make_type_with_address_space (follow_type,
-						       make_addr_space);
-	make_const = make_volatile = 0;
-	make_addr_space = 0;
+	make_restrict = make_atomic = false;
 	break;
       case tp_array:
 	array_size = pop_int ();
diff --git a/gdb/type-stack.h b/gdb/type-stack.h
index ee004d1..8060f2f 100644
--- a/gdb/type-stack.h
+++ b/gdb/type-stack.h
@@ -40,6 +40,8 @@ enum type_pieces
     tp_const, 
     tp_volatile, 
     tp_space_identifier,
+    tp_atomic,
+    tp_restrict,
     tp_type_stack,
     tp_kind
   };