gdb: move rust_language into rust-lang.h

Move the rust_language class declaration into the rust-lang.h header
file.  This allows for the function implementations called directly in
rust-lang.c and rust-exp.y without the need for trampoline functions.

There should be no user visible changes after this commit.

gdb/ChangeLog:

	* rust-exp.y (rust_parse): Rename to...
	(rust_language::parser): ...this.
	* rust-lang.c (-rust_printstr): Rename to...
	(rust_language::printstr): ...this.
	(rust_value_print_inner): Delete declaration.
	(val_print_struct): Rename to...
	(rust_language::val_print_struct): ...this.  Update calls to
	member functions.
	(rust_print_enum): Rename to...
	(rust_language::print_enum): ...this.  Update calls to member
	functions.
	(rust_value_print_inner): Rename to...
	(rust_language::value_print_inner): ...this.  Update calls to
	member functions.
	(exp_descriptor_rust): Rename to...
	(rust_language::exp_descriptor_tab): ...this.
	(class rust_language): Move to rust-lang.h.
	(rust_language::language_arch_info): Implementation moved to here
	from class declaration.
	(rust_language::print_type): Likewise.
	(rust_language::emitchar): Likewise.
	(rust_language::is_string_type_p): Likewise.
	* rust-lang.h: Add 'demangle.h', 'language.h', 'value.h', and
	'c-lang.h' includes.
	(rust_parse): Delete declaration.
	(class rust_language): Class declaration moved here from
	rust-lang.c.

gdb/rust-lang.h

@@ -20,12 +20,14 @@
 #ifndef RUST_LANG_H
 #define RUST_LANG_H
 
+#include "demangle.h"
+#include "language.h"
+#include "value.h"
+#include "c-lang.h"
+
 struct parser_state;
 struct type;
 
-/* The la_parser implementation for Rust.  */
-extern int rust_parse (struct parser_state *);
-
 /* Return true if TYPE is a tuple type; otherwise false.  */
 extern bool rust_tuple_type_p (struct type *type);
 
@@ -48,4 +50,194 @@ extern const char *rust_last_path_segment (const char *path);
 extern struct type *rust_slice_type (const char *name, struct type *elt_type,
 				     struct type *usize_type);
 
+/* Class representing the Rust language.  */
+
+class rust_language : public language_defn
+{
+public:
+  rust_language ()
+    : language_defn (language_rust)
+  { /* Nothing.  */ }
+
+  /* See language.h.  */
+
+  const char *name () const override
+  { return "rust"; }
+
+  /* See language.h.  */
+
+  const char *natural_name () const override
+  { return "Rust"; }
+
+  /* See language.h.  */
+
+  const std::vector<const char *> &filename_extensions () const override
+  {
+    static const std::vector<const char *> extensions = { ".rs" };
+    return extensions;
+  }
+
+  /* See language.h.  */
+
+  void language_arch_info (struct gdbarch *gdbarch,
+			   struct language_arch_info *lai) const override;
+
+  /* See language.h.  */
+
+  bool sniff_from_mangled_name (const char *mangled,
+				char **demangled) const override
+  {
+    *demangled = gdb_demangle (mangled, DMGL_PARAMS | DMGL_ANSI);
+    return *demangled != NULL;
+  }
+
+  /* See language.h.  */
+
+  char *demangle_symbol (const char *mangled, int options) const override
+  {
+    return gdb_demangle (mangled, options);
+  }
+
+  /* See language.h.  */
+
+  void print_type (struct type *type, const char *varstring,
+		   struct ui_file *stream, int show, int level,
+		   const struct type_print_options *flags) const override;
+
+  /* See language.h.  */
+
+  gdb::unique_xmalloc_ptr<char> watch_location_expression
+	(struct type *type, CORE_ADDR addr) const override
+  {
+    type = check_typedef (TYPE_TARGET_TYPE (check_typedef (type)));
+    std::string name = type_to_string (type);
+    return gdb::unique_xmalloc_ptr<char>
+      (xstrprintf ("*(%s as *mut %s)", core_addr_to_string (addr),
+		   name.c_str ()));
+  }
+
+  /* See language.h.  */
+
+  void value_print_inner
+	(struct value *val, struct ui_file *stream, int recurse,
+	 const struct value_print_options *options) const override;
+
+  /* See language.h.  */
+
+  struct block_symbol lookup_symbol_nonlocal
+	(const char *name, const struct block *block,
+	 const domain_enum domain) const override
+  {
+    struct block_symbol result = {};
+
+    if (symbol_lookup_debug)
+      {
+	fprintf_unfiltered (gdb_stdlog,
+			    "rust_lookup_symbol_non_local"
+			    " (%s, %s (scope %s), %s)\n",
+			    name, host_address_to_string (block),
+			    block_scope (block), domain_name (domain));
+      }
+
+    /* Look up bare names in the block's scope.  */
+    std::string scopedname;
+    if (name[cp_find_first_component (name)] == '\0')
+      {
+	const char *scope = block_scope (block);
+
+	if (scope[0] != '\0')
+	  {
+	    scopedname = std::string (scope) + "::" + name;
+	    name = scopedname.c_str ();
+	  }
+	else
+	  name = NULL;
+      }
+
+    if (name != NULL)
+      {
+	result = lookup_symbol_in_static_block (name, block, domain);
+	if (result.symbol == NULL)
+	  result = lookup_global_symbol (name, block, domain);
+      }
+    return result;
+  }
+
+  /* See language.h.  */
+
+  int parser (struct parser_state *ps) const override;
+
+  /* See language.h.  */
+
+  void emitchar (int ch, struct type *chtype,
+		 struct ui_file *stream, int quoter) const override;
+
+  /* See language.h.  */
+
+  void printchar (int ch, struct type *chtype,
+		  struct ui_file *stream) const override
+  {
+    fputs_filtered ("'", stream);
+    emitchar (ch, chtype, stream, '\'');
+    fputs_filtered ("'", stream);
+  }
+
+  /* See language.h.  */
+
+  void printstr (struct ui_file *stream, struct type *elttype,
+		 const gdb_byte *string, unsigned int length,
+		 const char *encoding, int force_ellipses,
+		 const struct value_print_options *options) const override;
+
+  /* See language.h.  */
+
+  void print_typedef (struct type *type, struct symbol *new_symbol,
+		      struct ui_file *stream) const override
+  {
+    type = check_typedef (type);
+    fprintf_filtered (stream, "type %s = ", new_symbol->print_name ());
+    type_print (type, "", stream, 0);
+    fprintf_filtered (stream, ";");
+  }
+
+  /* See language.h.  */
+
+  bool is_string_type_p (struct type *type) const override;
+
+  /* See language.h.  */
+
+  bool range_checking_on_by_default () const override
+  { return true; }
+
+  /* See language.h.  */
+
+  const struct exp_descriptor *expression_ops () const override
+  { return &exp_descriptor_tab; }
+
+  /* See language.h.  */
+
+  const struct op_print *opcode_print_table () const override
+  { return c_op_print_tab; }
+
+private:
+
+  /* Table of expression handling functions for use by EXPRESSION_OPS
+     member function.  */
+
+  static const struct exp_descriptor exp_descriptor_tab;
+
+  /* Helper for value_print_inner, arguments are as for that function.
+     Prints structs and untagged unions.  */
+
+  void val_print_struct (struct value *val, struct ui_file *stream,
+			 int recurse,
+			 const struct value_print_options *options) const;
+
+  /* Helper for value_print_inner, arguments are as for that function.
+     Prints discriminated unions (Rust enums).  */
+
+  void print_enum (struct value *val, struct ui_file *stream, int recurse,
+		   const struct value_print_options *options) const;
+};
+
 #endif /* RUST_LANG_H */