Implement Rust raw identifiers

This patch implements Rust raw identifiers in the lexer in gdb.  There
was an earlier patch to do this, but the contributor didn't reply to
my email asking whether he had sorted out his copyright assignment.

This is relatively straightforward, but a small test suite addition
was needd to ensure that the new test is skipped on older versions of
rustc -- ones that predate the introduction of raw identifiers.

gdb/ChangeLog
2021-06-11  Tom Tromey  <tom@tromey.com>

	PR rust/23427
	* rust-parse.c (rust_parser::lex_identifier): Handle raw
	identifiers.
	(rust_lex_tests): Add raw identifier tests.

gdb/testsuite/ChangeLog
2021-06-11  Tom Tromey  <tom@tromey.com>

	PR rust/23427
	* lib/rust-support.exp (rust_compiler_version): New caching proc.
	* gdb.rust/rawids.exp: New file.
	* gdb.rust/rawids.rs: New file.

gdb/ChangeLog

@@ -1,3 +1,10 @@
+2021-06-11  Tom Tromey  <tom@tromey.com>
+
+	PR rust/23427
+	* rust-parse.c (rust_parser::lex_identifier): Handle raw
+	identifiers.
+	(rust_lex_tests): Add raw identifier tests.
+
 2021-06-10  Simon Marchi  <simon.marchi@polymtl.ca>
 
 	* lib/gdb.exp (default_gdb_exit): Unset gdb_tty_name.

gdb/rust-parse.c

@@ -747,12 +747,21 @@ rust_identifier_start_p (char c)
 int
 rust_parser::lex_identifier ()
 {
-  const char *start = pstate->lexptr;
   unsigned int length;
   const struct token_info *token;
   int i;
   int is_gdb_var = pstate->lexptr[0] == '$';
 
+  bool is_raw = false;
+  if (pstate->lexptr[0] == 'r'
+      && pstate->lexptr[1] == '#'
+      && rust_identifier_start_p (pstate->lexptr[2]))
+    {
+      is_raw = true;
+      pstate->lexptr += 2;
+    }
+
+  const char *start = pstate->lexptr;
   gdb_assert (rust_identifier_start_p (pstate->lexptr[0]));
 
   ++pstate->lexptr;
@@ -769,13 +778,16 @@ rust_parser::lex_identifier ()
 
   length = pstate->lexptr - start;
   token = NULL;
-  for (i = 0; i < ARRAY_SIZE (identifier_tokens); ++i)
+  if (!is_raw)
     {
-      if (length == strlen (identifier_tokens[i].name)
-	  && strncmp (identifier_tokens[i].name, start, length) == 0)
+      for (i = 0; i < ARRAY_SIZE (identifier_tokens); ++i)
 	{
-	  token = &identifier_tokens[i];
-	  break;
+	  if (length == strlen (identifier_tokens[i].name)
+	      && strncmp (identifier_tokens[i].name, start, length) == 0)
+	    {
+	      token = &identifier_tokens[i];
+	      break;
+	    }
 	}
     }
 
@@ -789,6 +801,7 @@ rust_parser::lex_identifier ()
 	}
     }
   else if (token == NULL
+	   && !is_raw
 	   && (strncmp (start, "thread", length) == 0
 	       || strncmp (start, "task", length) == 0)
 	   && space_then_number (pstate->lexptr))
@@ -2300,6 +2313,13 @@ rust_lex_tests (void)
   rust_lex_stringish_test (&parser, "hibob", "hibob", IDENT);
   rust_lex_stringish_test (&parser, "hibob__93", "hibob__93", IDENT);
   rust_lex_stringish_test (&parser, "thread", "thread", IDENT);
+  rust_lex_stringish_test (&parser, "r#true", "true", IDENT);
+
+  const int expected1[] = { IDENT, DECIMAL_INTEGER, 0 };
+  rust_lex_test_sequence (&parser, "r#thread 23", ARRAY_SIZE (expected1),
+			  expected1);
+  const int expected2[] = { IDENT, '#', 0 };
+  rust_lex_test_sequence (&parser, "r#", ARRAY_SIZE (expected2), expected2);
 
   rust_lex_stringish_test (&parser, "\"string\"", "string", STRING);
   rust_lex_stringish_test (&parser, "\"str\\ting\"", "str\ting", STRING);

gdb/testsuite/ChangeLog

@@ -1,3 +1,10 @@
+2021-06-11  Tom Tromey  <tom@tromey.com>
+
+	PR rust/23427
+	* lib/rust-support.exp (rust_compiler_version): New caching proc.
+	* gdb.rust/rawids.exp: New file.
+	* gdb.rust/rawids.rs: New file.
+
 2021-06-10  Tom de Vries  <tdevries@suse.de>
 
 	* gdb.mi/user-selected-context-sync.c (child_sub_function, main):

gdb/testsuite/gdb.rust/rawids.exp

@@ -0,0 +1,41 @@
+# Copyright (C) 2021 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test raw identifiers.
+
+load_lib rust-support.exp
+if {[skip_rust_tests]} {
+    continue
+}
+
+set v [split [rust_compiler_version] .]
+if {[lindex $v 0] == 1 && [lindex $v 1] < 30} {
+    untested "raw identifiers require rust 1.30 or greater"
+    return -1
+}
+
+standard_testfile .rs
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug rust}]} {
+    return -1
+}
+
+set line [gdb_get_line_number "set breakpoint here"]
+if {![runto ${srcfile}:$line]} {
+    untested "could not run to breakpoint"
+    return -1
+}
+
+gdb_test "print r#if" " = 23"
+gdb_test "print r#thread" " = 27"

gdb/testsuite/gdb.rust/rawids.rs

@@ -0,0 +1,26 @@
+// Copyright (C) 2021 Free Software Foundation, Inc.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#![allow(dead_code)]
+#![allow(unused_variables)]
+#![allow(unused_assignments)]
+
+
+fn main () {
+    let r#if = 23;
+    let thread = 27;
+
+    println!("{}, {}", r#if, r#thread);        // set breakpoint here
+}

gdb/testsuite/lib/rust-support.exp

@@ -54,3 +54,20 @@ gdb_caching_proc rust_llvm_version {
     }
     return 0.0
 }
+
+# Return the version of the Rust compiler.
+gdb_caching_proc rust_compiler_version {
+    set rustc [find_rustc]
+    if {$rustc == ""} {
+	verbose "could not find rustc"
+    } else {
+	set output [lindex [remote_exec host "$rustc --version --verbose"] 1]
+	foreach line [split $output \n] {
+	    if {[regexp "rustc (\[0-9.\]+) .*\$" $output ignore version]} {
+		return $version
+	    }
+	}
+	verbose "could not match rustc version output: $output"
+    }
+    return 0.0
+}