[RFA] Add new language: "unsupported"

[Joel Brobecker <brobecker@gnat.com>]

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As promised to Elena, this is a followup on: 

    http://sources.redhat.com/ml/gdb-patches/2003-04/msg00209.html

Basically, I added a new "unsupported" language which support is
minimalistic (identical to what we do with the "asm" language).
I didn't fancy "partial":

        (gdb) show lang
        Current language:  auto; currently partial

I felt like it could confuse the user to think that "partial" is the
name of a real language :-). But I'm not such a big fan of "unsupported"
either, so all suggestions are welcome.

This new language will first be used by the dwarf2 reader, for objects
which language is currently not supported. What it does, at the moment,
is use the "unknown" language, which makes a lot of the GDB commands
fall flat. Like so, when debugging an Ada program:

    (gdb) list foo.adb:1
    internal error - unimplemented function unk_lang_create_fundamental_type called.
    (gdb) quit

With the attached patch, and also the little patch to dwarf2read.c
(attached too, will be submitted later, after this one is agreed on),
GDB behaves in a much more friendly way:

    (gdb) list foo.adb:1
    1       procedure Foo is
    2          A : Integer := 1;
    3       begin
    4          A := A + 1;
    5       end Foo;
    (gdb) b foo.adb:4
    Breakpoint 1 at 0x8049769: file foo.adb, line 4.
    (gdb) run
    Starting program: /lek.a/brobecke/ada_example/foo 
    
    Breakpoint 1, _ada_foo () at foo.adb:4
    4          A := A + 1;
    Current language:  auto; currently unsupported
    (gdb) p a
    $1 = 1

2003-05-06  J. Brobecker  <brobecker@gnat.com>

        * defs.h (language): Add language_unsupported enum value.
        * c-lang.c (unsupported_language_defn): New language definition.
        (_initialize_c_language): Add the new unsupported language to
        the list of languages known to GDB.

Ok to apply?

Thanks,
-- 
Joel

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Index: defs.h
===================================================================
RCS file: /cvs/src/src/gdb/defs.h,v
retrieving revision 1.118
diff -c -3 -p -r1.118 defs.h
*** defs.h	10 Apr 2003 02:18:40 -0000	1.118
--- defs.h	7 May 2003 01:23:11 -0000
*************** enum language
*** 211,217 ****
      language_m2,		/* Modula-2 */
      language_asm,		/* Assembly language */
      language_scm,    		/* Scheme / Guile */
!     language_pascal		/* Pascal */
    };
  
  enum precision_type
--- 211,218 ----
      language_m2,		/* Modula-2 */
      language_asm,		/* Assembly language */
      language_scm,    		/* Scheme / Guile */
!     language_pascal,		/* Pascal */
!     language_unsupported	/* All other (unsupported) languages */
    };
  
  enum precision_type
Index: c-lang.c
===================================================================
RCS file: /cvs/src/src/gdb/c-lang.c,v
retrieving revision 1.18
diff -c -3 -p -r1.18 c-lang.c
*** c-lang.c	2 Apr 2003 03:02:46 -0000	1.18
--- c-lang.c	7 May 2003 01:23:04 -0000
*************** const struct language_defn asm_language_
*** 651,660 ****
--- 651,692 ----
    LANG_MAGIC
  };
  
+ const struct language_defn unsupported_language_defn =
+ {
+   "unsupported",			/* Language name */
+   language_unsupported,
+   c_builtin_types,
+   range_check_off,
+   type_check_off,
+   case_sensitive_on,
+   c_preprocess_and_parse,
+   c_error,
+   evaluate_subexp_standard,
+   c_printchar,			/* Print a character constant */
+   c_printstr,			/* Function to print string constant */
+   c_emit_char,			/* Print a single char */
+   c_create_fundamental_type,	/* Create fundamental type in this language */
+   c_print_type,			/* Print a type using appropriate syntax */
+   c_val_print,			/* Print a value using appropriate syntax */
+   c_value_print,		/* Print a top-level value */
+   NULL,				/* Language specific skip_trampoline */
+   NULL,				/* Language specific symbol demangler */
+   {"", "", "", ""},		/* Binary format info */
+   {"0%lo", "0", "o", ""},	/* Octal format info */
+   {"%ld", "", "d", ""},		/* Decimal format info */
+   {"0x%lx", "0x", "x", ""},	/* Hex format info */
+   c_op_print_tab,		/* expression operators for printing */
+   1,				/* c-style arrays */
+   0,				/* String lower bound */
+   &builtin_type_char,		/* Type of string elements */
+   LANG_MAGIC
+ };
+ 
  void
  _initialize_c_language (void)
  {
    add_language (&c_language_defn);
    add_language (&cplus_language_defn);
    add_language (&asm_language_defn);
+   add_language (&unsupported_language_defn);
  }

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Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.90
diff -c -3 -p -r1.90 dwarf2read.c
*** dwarf2read.c	15 Apr 2003 23:07:11 -0000	1.90
--- dwarf2read.c	7 May 2003 01:23:14 -0000
*************** set_cu_language (unsigned int lang)
*** 4548,4554 ****
      case DW_LANG_Pascal83:
      case DW_LANG_Modula2:
      default:
!       cu_language = language_unknown;
        break;
      }
    cu_language_defn = language_def (cu_language);
--- 4548,4554 ----
      case DW_LANG_Pascal83:
      case DW_LANG_Modula2:
      default:
!       cu_language = language_unsupported;
        break;
      }
    cu_language_defn = language_def (cu_language);