Re: [PATCH 1/6] Fix "ptype INTERNAL_FUNC" (PR gdb/30105)

[Andrew Burgess <aburgess@redhat.com>]

Pedro Alves <pedro@palves.net> writes:

> Currently, looking at the type of an internal function, like below,
> hits an odd error:
>
>  (gdb) ptype $_isvoid
>  type = <internal function>type not handled in c_type_print_varspec_prefix()
>
> That is an error thrown from
> c-typeprint.c:c_type_print_varspec_prefix, where it reads:
>
>     ...
>     case TYPE_CODE_DECFLOAT:
>     case TYPE_CODE_FIXED_POINT:
>       /* These types need no prefix.  They are listed here so that
> 	 gcc -Wall will reveal any types that haven't been handled.  */
>       break;
>     default:
>       error (_("type not handled in c_type_print_varspec_prefix()"));
>       break;
>
> Internal function types have type code TYPE_CODE_INTERNAL_FUNCTION,
> which is not explicitly handled by that switch.
>
> That comment quoted above says that gcc -Wall will reveal any types
> that haven't been handled, but that's not actually true, at least with
> modern GCCs.  You would need to enable -Wswitch-enum for that, which
> we don't.  If I do enable that warning, then I see that we're missing
> handling for the following type codes:
>
>    TYPE_CODE_INTERNAL_FUNCTION,
>    TYPE_CODE_MODULE,
>    TYPE_CODE_NAMELIST,
>    TYPE_CODE_XMETHOD
>
> TYPE_CODE_MODULE and TYPE_CODE_NAMELIST and Fortran-specific, so it'd
> be a little weird to handle them here.
>
> I tried to reach this code with TYPE_CODE_XMETHOD, but couldn't figure
> out how to.  ptype on an xmethod isn't treated specially, it just
> complains that the method doesn't exist.  I've extended the
> gdb.python/py-xmethods.exp testcase to make sure of that.
>
> My thinking is that whatever type code we add next, the most likely
> scenario is that it won't need any special handling, so we'd just be
> adding another case to that "do nothing" list.  If we do need special
> casing for whatever type code, I think that tests added at the same
> time as the feature would uncover it anyhow.  If we do miss adding the
> special casing, then it still looks better to me to print the type
> somewhat incompletely than to error out and make it harder for users
> to debug whatever they need.  So I think that the best thing to do
> here is to just remove all those explicit "do nothing" cases, along
> with the error default case.
>
> After doing that, I decided to write a testcase that iterates over all
> supported languages doing "ptype INTERNAL_FUNC".  That revealed that
> Pascal has a similar problem, except the default case hits a
> gdb_assert instead of an error:
>
>  (gdb) with language pascal -- ptype $_isvoid
>  type =
>  ../../src/gdb/p-typeprint.c:268: internal-error: type_print_varspec_prefix: unexpected type
>  A problem internal to GDB has been detected,
>  further debugging may prove unreliable.
>
> That is fixed by this patch in the same way.
>
> You'll notice that the new testcase special-cases the Ada expected
> output:
>
> 	} elseif {$lang == "ada"} {
> 	    gdb_test "ptype \$_isvoid" "<<internal function>>"
> 	} else {
> 	    gdb_test "ptype \$_isvoid" "<internal function>"
> 	}
>
> That will be subject of the following patch.
>
> Change-Id: I81aec03523cceb338b5180a0b4c2e4ad26b4c4db
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30105

LGTM.

Thanks,
Andrew

> ---
>  gdb/c-typeprint.c                             | 51 -------------------
>  gdb/p-typeprint.c                             | 46 -----------------
>  .../gdb.base/internal-functions-ptype.exp     | 42 +++++++++++++++
>  gdb/testsuite/gdb.python/py-xmethods.exp      |  8 +++
>  4 files changed, 50 insertions(+), 97 deletions(-)
>  create mode 100644 gdb/testsuite/gdb.base/internal-functions-ptype.exp
>
> diff --git a/gdb/c-typeprint.c b/gdb/c-typeprint.c
> index dca96231117..7e9d941a435 100644
> --- a/gdb/c-typeprint.c
> +++ b/gdb/c-typeprint.c
> @@ -441,31 +441,6 @@ c_type_print_varspec_prefix (struct type *type,
>  				   stream, show, passed_a_ptr, 0,
>  				   language, flags, podata);
>        break;
> -
> -    case TYPE_CODE_UNDEF:
> -    case TYPE_CODE_STRUCT:
> -    case TYPE_CODE_UNION:
> -    case TYPE_CODE_ENUM:
> -    case TYPE_CODE_FLAGS:
> -    case TYPE_CODE_INT:
> -    case TYPE_CODE_FLT:
> -    case TYPE_CODE_VOID:
> -    case TYPE_CODE_ERROR:
> -    case TYPE_CODE_CHAR:
> -    case TYPE_CODE_BOOL:
> -    case TYPE_CODE_SET:
> -    case TYPE_CODE_RANGE:
> -    case TYPE_CODE_STRING:
> -    case TYPE_CODE_COMPLEX:
> -    case TYPE_CODE_NAMESPACE:
> -    case TYPE_CODE_DECFLOAT:
> -    case TYPE_CODE_FIXED_POINT:
> -      /* These types need no prefix.  They are listed here so that
> -	 gcc -Wall will reveal any types that haven't been handled.  */
> -      break;
> -    default:
> -      error (_("type not handled in c_type_print_varspec_prefix()"));
> -      break;
>      }
>  }
>  
> @@ -821,32 +796,6 @@ c_type_print_varspec_suffix (struct type *type,
>        c_type_print_varspec_suffix (type->target_type (), stream,
>  				   show, passed_a_ptr, 0, language, flags);
>        break;
> -
> -    case TYPE_CODE_UNDEF:
> -    case TYPE_CODE_STRUCT:
> -    case TYPE_CODE_UNION:
> -    case TYPE_CODE_FLAGS:
> -    case TYPE_CODE_ENUM:
> -    case TYPE_CODE_INT:
> -    case TYPE_CODE_FLT:
> -    case TYPE_CODE_VOID:
> -    case TYPE_CODE_ERROR:
> -    case TYPE_CODE_CHAR:
> -    case TYPE_CODE_BOOL:
> -    case TYPE_CODE_SET:
> -    case TYPE_CODE_RANGE:
> -    case TYPE_CODE_STRING:
> -    case TYPE_CODE_COMPLEX:
> -    case TYPE_CODE_NAMESPACE:
> -    case TYPE_CODE_DECFLOAT:
> -    case TYPE_CODE_FIXED_POINT:
> -      /* These types do not need a suffix.  They are listed so that
> -	 gcc -Wall will report types that may not have been
> -	 considered.  */
> -      break;
> -    default:
> -      error (_("type not handled in c_type_print_varspec_suffix()"));
> -      break;
>      }
>  }
>  
> diff --git a/gdb/p-typeprint.c b/gdb/p-typeprint.c
> index e8542d6845a..7458aa6c095 100644
> --- a/gdb/p-typeprint.c
> +++ b/gdb/p-typeprint.c
> @@ -244,29 +244,6 @@ pascal_language::type_print_varspec_prefix (struct type *type,
>  		    plongest (type->bounds ()->high.const_val ()));
>        gdb_printf (stream, "of ");
>        break;
> -
> -    case TYPE_CODE_UNDEF:
> -    case TYPE_CODE_STRUCT:
> -    case TYPE_CODE_UNION:
> -    case TYPE_CODE_ENUM:
> -    case TYPE_CODE_INT:
> -    case TYPE_CODE_FLT:
> -    case TYPE_CODE_VOID:
> -    case TYPE_CODE_ERROR:
> -    case TYPE_CODE_CHAR:
> -    case TYPE_CODE_BOOL:
> -    case TYPE_CODE_SET:
> -    case TYPE_CODE_RANGE:
> -    case TYPE_CODE_STRING:
> -    case TYPE_CODE_COMPLEX:
> -    case TYPE_CODE_TYPEDEF:
> -    case TYPE_CODE_FIXED_POINT:
> -      /* These types need no prefix.  They are listed here so that
> -	 gcc -Wall will reveal any types that haven't been handled.  */
> -      break;
> -    default:
> -      gdb_assert_not_reached ("unexpected type");
> -      break;
>      }
>  }
>  
> @@ -377,29 +354,6 @@ pascal_language::type_print_varspec_suffix (struct type *type,
>        type_print_func_varspec_suffix (type, stream, show,
>  					     passed_a_ptr, 0, flags);
>        break;
> -
> -    case TYPE_CODE_UNDEF:
> -    case TYPE_CODE_STRUCT:
> -    case TYPE_CODE_UNION:
> -    case TYPE_CODE_ENUM:
> -    case TYPE_CODE_INT:
> -    case TYPE_CODE_FLT:
> -    case TYPE_CODE_VOID:
> -    case TYPE_CODE_ERROR:
> -    case TYPE_CODE_CHAR:
> -    case TYPE_CODE_BOOL:
> -    case TYPE_CODE_SET:
> -    case TYPE_CODE_RANGE:
> -    case TYPE_CODE_STRING:
> -    case TYPE_CODE_COMPLEX:
> -    case TYPE_CODE_TYPEDEF:
> -    case TYPE_CODE_FIXED_POINT:
> -      /* These types do not need a suffix.  They are listed so that
> -	 gcc -Wall will report types that may not have been considered.  */
> -      break;
> -    default:
> -      gdb_assert_not_reached ("unexpected type");
> -      break;
>      }
>  }
>  
> diff --git a/gdb/testsuite/gdb.base/internal-functions-ptype.exp b/gdb/testsuite/gdb.base/internal-functions-ptype.exp
> new file mode 100644
> index 00000000000..42caae05aad
> --- /dev/null
> +++ b/gdb/testsuite/gdb.base/internal-functions-ptype.exp
> @@ -0,0 +1,42 @@
> +# Copyright 2023 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 "ptype INTERNAL_FUNCTION" in all languages.
> +
> +proc test_ptype_internal_function {} {
> +    set all_languages [get_set_option_choices "set language"]
> +
> +    foreach_with_prefix lang $all_languages {
> +	if { $lang == "auto" || $lang == "local" } {
> +	    # Avoid duplicate testing.
> +	    continue
> +	}
> +
> +	gdb_test_no_output "set language $lang"
> +
> +	if {$lang == "unknown"} {
> +	    gdb_test "ptype \$_isvoid" \
> +		"expression parsing not implemented for language \"Unknown\""
> +	} elseif {$lang == "ada"} {
> +	    gdb_test "ptype \$_isvoid" "<<internal function>>"
> +	} else {
> +	    gdb_test "ptype \$_isvoid" "<internal function>"
> +	}
> +    }
> +}
> +
> +clean_restart
> +
> +test_ptype_internal_function
> diff --git a/gdb/testsuite/gdb.python/py-xmethods.exp b/gdb/testsuite/gdb.python/py-xmethods.exp
> index 97d560476fc..2cf7bbb68b0 100644
> --- a/gdb/testsuite/gdb.python/py-xmethods.exp
> +++ b/gdb/testsuite/gdb.python/py-xmethods.exp
> @@ -52,6 +52,9 @@ gdb_test "p a_geta" ".* = 1" "before: a_geta 1"
>  gdb_test "p ++a1" "No symbol.*" "before: ++a1"
>  gdb_test "p a1.getarrayind(5)" "Couldn't find method.*" \
>    "before: a1.getarrayind(5)"
> +gdb_test "ptype a1.getarrayind" \
> +    "There is no member or method named getarrayind\\." \
> +    "before: ptype a1.getarrayind"
>  
>  gdb_test "p a_ptr->geta()" ".* = 60" "before: a_ptr->geta()"
>  gdb_test "p b_geta" ".* = 1" "before: b_geta 1"
> @@ -94,9 +97,14 @@ gdb_test "p b1 - a1" ".* = 25" "after: b1 - a1"
>  gdb_test "p a_minus_a" ".* = 4" "after: a_minus_a 4"
>  
>  gdb_test "p a1.geta()" "From Python <A_geta>.*5" "after: a1.geta()"
> +
>  gdb_test "p ++a1" "From Python <plus_plus_A>.*6" "after: ++a1"
>  gdb_test "p a1.getarrayind(5)" "From Python <A_getarrayind>.*5" \
>    "after: a1.getarrayind(5)"
> +gdb_test "ptype a1.getarrayind" \
> +  "There is no member or method named getarrayind\\." \
> +  "after: ptype a1.getarrayind"
> +
>  gdb_test "p a1\[6\]" ".*int &.*6" "after a1\[\]"
>  gdb_test "p b1\[7\]" ".*const int &.*7" "after b1\[\]"
>  # Note the following test.  Xmethods on dynamc types are not looked up
> -- 
> 2.36.0