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Re: [RFA]: Turn on Ada support, take 2
Here is an update to the patch I sent previously. In this version, I have
1. Removed the compilation of ada-tasks.o, since we have not yet turned
on any of it in the public version.
2. Responded to most of Eli's comments. I will have to consider the
issue of formating things like 'Address, since the standard rendering
in info files provided by the technically appropriate marker,
@code, looks rather bad (in my opinion), due to the adjacent quotes
at the beginning.
A previous patch to the Ada sources added some conditionalization to mark code
that is not yet used in the public version (for the benefit of reviewers).
ChangeLogs:
2004-06-16 Paul N. Hilfinger <Hilfinger@gnat.com>
Turn on initial Ada support (mainly expression evaluation).
* Makefile.in (ada_lex_c): Define
(HFILES_NO_SRCDIR): Add ada-lang.h.
(COMMON_OBS): Add ada-lang.o, ada-typeprint.o, ada-valprint.o.
(YYOBJ): Add ada-exp.o.
(rule .l.c): Generalize to not mention ada.
(ada-lex.o): Remove (ada-lex.c is included by ada-exp.y).
(ada-lang.o): Add dependencies on completer.h, gdb_obstack.h,
hashtab.h.
(ada-tasks.o): Add dependency on gdb_string.h.
(ada-valprint.o): Add dependency on gdb_string.h.
* symtab.c: Add dependency on ada-lang.h.
(symbol_natural_name): Add Ada case.
(symbol_demangled_name): Add Ada case.
(symbol_search_name): Add Ada case.
* symfile.c (init_filename_language_table): Add extensions for
Ada.
* defs.h (enum language): Add language_ada.
* gdbtypes.h (TYPE_FLAG_FIXED_INSTANCE): Define.
2004-06-09 Paul N. Hilfinger <hilfinger@gnat.com>
* doc/gdb.texinfo (Filenames): Add Ada suffixes.
(Ada) New section.
Index: gdb/Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.587
diff -u -p -r1.587 Makefile.in
--- gdb/Makefile.in 14 Jun 2004 20:40:39 -0000 1.587
+++ gdb/Makefile.in 16 Jun 2004 08:23:45 -0000
@@ -616,6 +616,7 @@ nm_h = @nm_h@
# gdb/ headers
#
+ada_lex_c = ada-lex.c
ada_lang_h = ada-lang.h $(value_h) $(gdbtypes_h)
alphabsd_tdep_h = alphabsd-tdep.h
alpha_tdep_h = alpha-tdep.h
@@ -833,7 +834,7 @@ HFILES_NO_SRCDIR = bcache.h buildsym.h c
symfile.h symfile-mem.h stabsread.h target.h terminal.h typeprint.h \
xcoffsolib.h \
macrotab.h macroexp.h macroscope.h \
- c-lang.h f-lang.h \
+ ada-lang.h c-lang.h f-lang.h \
jv-lang.h \
m2-lang.h p-lang.h \
complaints.h valprint.h \
@@ -894,7 +895,7 @@ COMMON_OBS = $(DEPFILES) $(YYOBJ) \
dbxread.o coffread.o coff-pe-read.o elfread.o \
dwarfread.o dwarf2read.o mipsread.o stabsread.o corefile.o \
dwarf2expr.o dwarf2loc.o dwarf2-frame.o \
- c-lang.o f-lang.o objc-lang.o \
+ ada-lang.o c-lang.o f-lang.o objc-lang.o \
ui-out.o cli-out.o \
varobj.o wrapper.o \
jv-lang.o jv-valprint.o jv-typeprint.o \
@@ -902,8 +903,8 @@ COMMON_OBS = $(DEPFILES) $(YYOBJ) \
scm-exp.o scm-lang.o scm-valprint.o \
sentinel-frame.o \
complaints.o typeprint.o \
- c-typeprint.o f-typeprint.o m2-typeprint.o \
- c-valprint.o cp-valprint.o f-valprint.o m2-valprint.o \
+ ada-typeprint.o c-typeprint.o f-typeprint.o m2-typeprint.o \
+ ada-valprint.o c-valprint.o cp-valprint.o f-valprint.o m2-valprint.o \
nlmread.o serial.o mdebugread.o top.o utils.o \
ui-file.o \
user-regs.o \
@@ -927,6 +928,7 @@ YYFILES = c-exp.c \
f-exp.c m2-exp.c p-exp.c
YYOBJ = c-exp.o \
objc-exp.o \
+ ada-exp.o \
jv-exp.o \
f-exp.o m2-exp.o p-exp.o
@@ -1495,7 +1497,7 @@ valprint.o: $(srcdir)/valprint.c
echo $(FLEX) -Isit $< ">" $@; \
$(FLEX) -Isit $< > $@; \
elif [ ! -f $@ -a ! -f $< ]; then \
- echo "ada-lex.c missing and flex not available."; \
+ echo "$< missing and flex not available."; \
false; \
elif [ ! -f $@ ]; then \
echo "Warning: $*.c older than $*.l and flex not available."; \
@@ -1522,18 +1524,18 @@ ada-lang.o: ada-lang.c $(gdb_string_h) $
$(gdbtypes_h) $(gdbcmd_h) $(expression_h) $(parser_defs_h) \
$(language_h) $(c_lang_h) $(inferior_h) $(symfile_h) $(objfiles_h) \
$(breakpoint_h) $(gdbcore_h) $(ada_lang_h) $(ui_out_h) $(block_h) \
- $(infcall_h) $(dictionary_h)
-ada-lex.o: ada-lex.c
+ $(completer_h) $(infcall_h) $(gdb_obstack_h) $(dictionary_h) \
+ $(hashtab_h)
ada-tasks.o: ada-tasks.c $(defs_h) $(command_h) $(value_h) $(language_h) \
$(inferior_h) $(symtab_h) $(target_h) $(regcache_h) $(gdbcore_h) \
- $(gregset_h) $(ada_lang_h)
+ $(gregset_h) $(gdb_string_h) $(ada_lang_h)
ada-typeprint.o: ada-typeprint.c $(defs_h) $(gdb_obstack_h) $(bfd_h) \
$(symtab_h) $(gdbtypes_h) $(expression_h) $(value_h) $(gdbcore_h) \
$(target_h) $(command_h) $(gdbcmd_h) $(language_h) $(demangle_h) \
$(c_lang_h) $(typeprint_h) $(ada_lang_h) $(gdb_string_h)
ada-valprint.o: ada-valprint.c $(defs_h) $(symtab_h) $(gdbtypes_h) \
$(expression_h) $(value_h) $(demangle_h) $(valprint_h) $(language_h) \
- $(annotate_h) $(ada_lang_h) $(c_lang_h) $(infcall_h)
+ $(annotate_h) $(ada_lang_h) $(c_lang_h) $(gdb_string_h) $(infcall_h)
aix-thread.o: aix-thread.c $(defs_h) $(gdb_assert_h) $(gdbthread_h) \
$(target_h) $(inferior_h) $(regcache_h) $(gdbcmd_h) $(language_h) \
$(ppc_tdep_h) $(gdb_string_h)
Index: gdb/defs.h
===================================================================
RCS file: /cvs/src/src/gdb/defs.h,v
retrieving revision 1.147
diff -u -p -r1.147 defs.h
--- gdb/defs.h 10 Jun 2004 20:05:43 -0000 1.147
+++ gdb/defs.h 16 Jun 2004 08:23:45 -0000
@@ -220,6 +220,7 @@ enum language
language_asm, /* Assembly language */
language_scm, /* Scheme / Guile */
language_pascal, /* Pascal */
+ language_ada, /* Ada */
language_minimal /* All other languages, minimal support only */
};
Index: gdb/gdbtypes.h
===================================================================
RCS file: /cvs/src/src/gdb/gdbtypes.h,v
retrieving revision 1.53
diff -u -p -r1.53 gdbtypes.h
--- gdb/gdbtypes.h 2 Jun 2004 21:01:55 -0000 1.53
+++ gdb/gdbtypes.h 16 Jun 2004 08:23:45 -0000
@@ -273,6 +273,17 @@ enum type_code
#define TYPE_ADDRESS_CLASS_ALL(t) (TYPE_INSTANCE_FLAGS(t) \
& TYPE_FLAG_ADDRESS_CLASS_ALL)
+/* The debugging formats (especially STABS) do not contain enough information
+ to represent all Ada types---especially those whose size depends on
+ dynamic quantities. Therefore, the GNAT Ada compiler includes
+ extra information in the form of additional type definitions
+ connected by naming conventions. This flag indicates that the
+ type is an ordinary (unencoded) GDB type that has been created from
+ the necessary run-time information, and does not need further
+ interpretation. Optionally marks ordinary, fixed-size GDB type. */
+
+#define TYPE_FLAG_FIXED_INSTANCE (1 << 15)
+
/* Array bound type. */
enum array_bound_type
{
Index: gdb/symfile.c
===================================================================
RCS file: /cvs/src/src/gdb/symfile.c,v
retrieving revision 1.132
diff -u -p -r1.132 symfile.c
--- gdb/symfile.c 15 Jun 2004 01:04:20 -0000 1.132
+++ gdb/symfile.c 16 Jun 2004 08:23:46 -0000
@@ -2158,6 +2158,10 @@ init_filename_language_table (void)
add_filename_language (".pas", language_pascal);
add_filename_language (".p", language_pascal);
add_filename_language (".pp", language_pascal);
+ add_filename_language (".adb", language_ada);
+ add_filename_language (".ads", language_ada);
+ add_filename_language (".a", language_ada);
+ add_filename_language (".ada", language_ada);
}
}
Index: gdb/symtab.c
===================================================================
RCS file: /cvs/src/src/gdb/symtab.c,v
retrieving revision 1.132
diff -u -p -r1.132 symtab.c
--- gdb/symtab.c 10 Jun 2004 20:05:44 -0000 1.132
+++ gdb/symtab.c 16 Jun 2004 08:23:47 -0000
@@ -41,6 +41,7 @@
#include "source.h"
#include "filenames.h" /* for FILENAME_CMP */
#include "objc-lang.h"
+#include "ada-lang.h"
#include "hashtab.h"
@@ -632,17 +633,24 @@ symbol_init_demangled_name (struct gener
char *
symbol_natural_name (const struct general_symbol_info *gsymbol)
{
- if ((gsymbol->language == language_cplus
- || gsymbol->language == language_java
- || gsymbol->language == language_objc)
- && (gsymbol->language_specific.cplus_specific.demangled_name != NULL))
+ switch (gsymbol->language)
{
- return gsymbol->language_specific.cplus_specific.demangled_name;
- }
- else
- {
- return gsymbol->name;
+ case language_cplus:
+ case language_java:
+ case language_objc:
+ if (gsymbol->language_specific.cplus_specific.demangled_name != NULL)
+ return gsymbol->language_specific.cplus_specific.demangled_name;
+ break;
+ case language_ada:
+ if (gsymbol->language_specific.cplus_specific.demangled_name != NULL)
+ return gsymbol->language_specific.cplus_specific.demangled_name;
+ else
+ return ada_decode_symbol (gsymbol);
+ break;
+ default:
+ break;
}
+ return gsymbol->name;
}
/* Return the demangled name for a symbol based on the language for
@@ -650,13 +658,24 @@ symbol_natural_name (const struct genera
char *
symbol_demangled_name (struct general_symbol_info *gsymbol)
{
- if (gsymbol->language == language_cplus
- || gsymbol->language == language_java
- || gsymbol->language == language_objc)
- return gsymbol->language_specific.cplus_specific.demangled_name;
-
- else
- return NULL;
+ switch (gsymbol->language)
+ {
+ case language_cplus:
+ case language_java:
+ case language_objc:
+ if (gsymbol->language_specific.cplus_specific.demangled_name != NULL)
+ return gsymbol->language_specific.cplus_specific.demangled_name;
+ break;
+ case language_ada:
+ if (gsymbol->language_specific.cplus_specific.demangled_name != NULL)
+ return gsymbol->language_specific.cplus_specific.demangled_name;
+ else
+ return ada_decode_symbol (gsymbol);
+ break;
+ default:
+ break;
+ }
+ return NULL;
}
/* Return the search name of a symbol---generally the demangled or
@@ -664,7 +683,10 @@ symbol_demangled_name (struct general_sy
If there is no distinct demangled name, then returns the same value
(same pointer) as SYMBOL_LINKAGE_NAME. */
char *symbol_search_name (const struct general_symbol_info *gsymbol) {
- return symbol_natural_name (gsymbol);
+ if (gsymbol->language == language_ada)
+ return gsymbol->name;
+ else
+ return symbol_natural_name (gsymbol);
}
/* Initialize the structure fields to zero values. */
Index: gdb/doc/gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.206
diff -u -p -r1.206 gdb.texinfo
--- gdb/doc/gdb.texinfo 14 Jun 2004 22:26:33 -0000 1.206
+++ gdb/doc/gdb.texinfo 16 Jun 2004 08:23:53 -0000
@@ -7741,6 +7741,11 @@ If a source file name ends in one of the
@value{GDBN} infers that its language is the one indicated.
@table @file
+@item .ada
+@itemx .ads
+@itemx .adb
+@itemx .a
+Ada source file.
@item .c
C source file
@@ -8031,7 +8036,7 @@ being set automatically by @value{GDBN}.
@node Support
@section Supported languages
-@value{GDBN} supports C, C@t{++}, Objective-C, Fortran, Java, assembly, and Modula-2.
+@value{GDBN} supports C, C@t{++}, Objective-C, Fortran, Java, assembly, Modula-2, and Ada.
@c This is false ...
Some @value{GDBN} features may be used in expressions regardless of the
language you use: the @value{GDBN} @code{@@} and @code{::} operators,
@@ -8051,6 +8056,7 @@ language reference or tutorial.
* C:: C and C@t{++}
* Objective-C:: Objective-C
* Modula-2:: Modula-2
+* Ada:: Ada
@end menu
@node C
@@ -8666,7 +8672,7 @@ the description of an object. However,
with certain Objective-C libraries that have a particular hook
function, @code{_NSPrintForDebugger}, defined.
-@node Modula-2, , Objective-C, Support
+@node Modula-2, Ada, Objective-C, Support
@subsection Modula-2
@cindex Modula-2, @value{GDBN} support
@@ -9109,6 +9115,481 @@ address can be specified by an integral
In @value{GDBN} scripts, the Modula-2 inequality operator @code{#} is
interpreted as the beginning of a comment. Use @code{<>} instead.
+@node Ada
+@subsection Ada
+@cindex Ada
+
+The extensions made to @value{GDBN} for Ada only support
+output from the @sc{gnu} Ada (GNAT) compiler.
+Other Ada compilers are not currently supported, and
+attempting to debug executables produced by them is most likely
+to be difficult.
+
+
+@cindex expressions in Ada
+@menu
+* Ada Mode Intro:: General remarks on the Ada syntax
+ and semantics supported by Ada mode
+ in @value{GDBN}
+* Omissions from Ada:: Restrictions on the Ada expression syntax.
+* Additions to Ada:: Extensions of the Ada expression syntax.
+* Stopping Before Main Program:: Debugging the program during elaboration.
+* Ada Exceptions:: Setting breakpoints on exception handlers.
+* Ada Generic Units:: Dealing with generic instantiations.
+* Ada Glitches:: Known peculiarities of Ada mode.
+@end menu
+
+@node Ada Mode Intro
+@subsubsection Introduction
+@cindex Ada mode, general
+
+The Ada mode of @value{GDBN} supports a fairly large subset of Ada expression
+syntax, with some extensions.
+The philosophy behind the design of this subset is
+
+@itemize @bullet
+@item
+That @value{GDBN} should provide basic literals and access to operations for
+arithmetic, dereferencing, field selection, indexing, and subprogram calls,
+leaving more sophisticated computations to subprograms written into the
+program (which therefore may be called from @value{GDBN}).
+
+@item
+That type safety and strict adherence to Ada language restrictions
+are not particularly important to the @value{GDBN} user.
+
+@item
+That brevity is important to the @value{GDBN} user.
+@end itemize
+
+Thus, for brevity, the debugger acts as if there were
+implicit @code{with} and @code{use} clauses in effect for all user-written
+packages, making it unnecessary to fully qualify most names with
+their packages, regardless of context. Where this causes ambiguity,
+@value{GDBN} asks the user's intent.
+
+The debugger will start in Ada mode if it detects an Ada main program.
+As for other languages, it will enter Ada mode when stopped in a program that
+was translated from an Ada source file.
+
+While in Ada mode, you may use `@t{--}' for comments. This is useful
+mostly for documenting command files. The standard @value{GDBN} comment
+(@samp{#}) still works at the beginning of a line in Ada mode, but not in the
+middle (to allow based literals).
+
+The debugger supports limited overloading. Given a subprogram call in which
+the function symbol has multiple definitions, it will use the number of
+actual parameters and some information about their types to attempt to narrow
+the set of definitions. It also makes very limited use of context, preferring
+procedures to functions in the context of the @code{call} command, and
+functions to procedures elsewhere.
+
+@node Omissions from Ada
+@subsubsection Omissions from Ada
+@cindex Ada, omissions from
+
+Here are the notable omissions from the subset:
+
+@itemize @bullet
+@item
+Only a subset of the attributes are supported:
+
+@itemize @minus
+@item
+@t{'First}, @t{'Last}, and @t{'Length}
+ on array objects (not on types and subtypes).
+
+@item
+@t{'Min} and @t{'Max}.
+
+@item
+@t{'Pos} and @t{'Val}.
+
+@item
+@t{'Tag}.
+
+@item
+@t{'Range} on array objects (not subtypes), but only as the right
+operand of the membership (@code{in}) operator.
+
+@item
+@t{'Access}, @t{'Unchecked_Access}, and
+@t{'Unrestricted_Access} (a GNAT extension).
+
+@item
+@t{'Address}.
+@end itemize
+
+@item
+The names in
+@code{Characters.Latin_1} are not available and
+concatenation is not implemented. Thus, escape characters in strings are
+not currently available.
+
+@item
+Equality tests (@samp{=} and @samp{/=}) on arrays test for bitwise
+equality of representations. They will generally work correctly
+for strings and arrays whose elements have integer or enumeration types.
+They may not work correctly for arrays whose element
+types have user-defined equality, for arrays of real values
+(in particular, IEEE-conformant floating point, because of negative
+zeroes and NaNs), and for arrays whose elements contain unused bits with
+indeterminate values.
+
+@item
+The other component-by-component array operations (@code{and}, @code{or},
+@code{xor}, @code{not}, and relational tests other than equality)
+are not implemented.
+
+@item
+There are no record or array aggregates.
+
+@item
+Dispatching subprogram calls are not implemented.
+
+@item
+The overloading algorithm is much more limited (i.e., less selective)
+than that of real Ada. It makes only limited use of the context in which a subexpression
+appears to resolve its meaning, and it is much looser in its rules for allowing
+type matches. As a result, some function calls will be ambiguous, and the user
+will be asked to choose the proper resolution.
+
+@item
+The @code{new} operator is not implemented.
+
+@item
+Entry calls are not implemented.
+
+@item
+Aside from printing, arithmetic operations on the native VAX floating-point
+formats are not supported.
+
+@item
+It is not possible to slice a packed array.
+@end itemize
+
+@node Additions to Ada
+@subsubsection Additions to Ada
+@cindex Ada, deviations from
+
+As it does for other languages, @value{GDBN} makes certain generic
+extensions to Ada (@pxref{Expressions}):
+
+@itemize @bullet
+@item
+If the expression @var{E} is a variable residing in memory
+(typically a local variable or array element) and @var{N} is
+a positive integer, then @code{@var{E}@@@var{N}} displays the values of
+@var{E} and the @var{N}-1 adjacent variables following it in memory as an array.
+In Ada, this operator is generally not necessary, since its prime use
+is in displaying parts of an array, and slicing will usually do this in Ada.
+However, there are occasional uses when debugging programs
+in which certain debugging information has been optimized away.
+
+@item
+@code{@var{B}::@var{var}} means ``the variable named @var{var} that appears
+in function or file @var{B}.'' When @var{B} is a file name, you must typically
+surround it in single quotes.
+
+@item
+The expression @code{@{@var{type}@} @var{addr}} means ``the variable of type
+@var{type} that appears at address @var{addr}.''
+
+@item
+A name starting with @samp{$} is a convenience variable
+(@pxref{Convenience Vars}) or a machine register (@pxref{Registers}).
+@end itemize
+
+In addition, @value{GDBN} provides a few other shortcuts and outright additions specific
+to Ada:
+
+@itemize @bullet
+@item
+The assignment statement is allowed as an expression, returning
+its right-hand operand as its value. Thus, you may enter
+
+@smallexample
+set x := y + 3
+print A(tmp := y + 1)
+@end smallexample
+
+@item
+The semicolon is allowed as an ``operator,'' returning as its value
+the value of its right-hand operand.
+This allows, for example,
+complex conditional breaks:
+
+@smallexample
+break f
+condition 1 (report(i); k += 1; A(k) > 100)
+@end smallexample
+
+@item
+Rather than use catenation and symbolic character names to introduce special
+characters into strings, one may instead use a special bracket notation,
+which is also used to print strings. A sequence of characters of the form
+@samp{["@var{XX}"]} within a string or character literal denotes the
+(single) character whose numeric encoding is @var{XX} in hexadecimal. The
+sequence of characters @samp{["""]} also denotes a single quotation mark
+in strings. For example,
+@smallexample
+ "One line.["0a"]Next line.["0a"]"
+@end smallexample
+@noindent
+Contains an ASCII newline character (@code{Ada.Characters.Latin_1.LF}) after each
+period.
+
+@item
+The subtype used as a prefix for the attributes @t{'Pos}, @t{'Min}, and
+@t{'Max} is optional (and is ignored in any case). For example, it is valid
+to write
+
+@smallexample
+print 'max(x, y)
+@end smallexample
+
+@item
+When printing arrays, @value{GDBN} uses positional notation when the
+array has a lower bound of 1, and uses a modified named notation otherwise.
+For example, a one-dimensional array of three integers with a lower bound of 3 might print as
+
+@smallexample
+(3 => 10, 17, 1)
+@end smallexample
+
+@noindent
+That is, in contrast to valid Ada, only the first component has a @code{=>}
+clause.
+
+@item
+You may abbreviate attributes in expressions with any unique,
+multi-character subsequence of
+their names (an exact match gets preference).
+For example, you may use @t{a'len}, @t{a'gth}, or @t{a'lh}
+in place of @t{a'length}.
+
+@item
+@cindex quoting Ada internal identifiers
+Since Ada is case-insensitive, the debugger normally maps identifiers you type
+to lower case. The GNAT compiler uses upper-case characters for
+some of its internal identifiers, which are normally of no interest to users.
+For the rare occasions when you actually have to look at them,
+enclose them in angle brackets to avoid the lower-case mapping.
+For example,
+@smallexample
+(gdb) print <JMPBUF_SAVE>[0]
+@end smallexample
+
+@item
+Printing an object of class-wide type or dereferencing an
+access-to-class-wide value will display all the components of the object's
+specific type (as indicated by its run-time tag). Likewise, component
+selection on such a value will operate on the specific type of the
+object.
+
+@end itemize
+
+@node Stopping Before Main Program
+@subsubsection Stopping at the Very Beginning
+
+@cindex breakpointing Ada elaboration code
+It is sometimes necessary to debug the program during elaboration, and
+before reaching the main procedure.
+As defined in the Ada Reference
+Manual, the elaboration code is invoked from a procedure called
+@code{adainit}. To run your program up to the beginning of
+elaboration, simply use the following two commands:
+@code{tbreak adainit} and @code{run}.
+
+@node Ada Exceptions
+@subsubsection Breaking on Ada Exceptions
+@cindex Ada, exceptions
+
+In Ada mode, you can set breakpoints that trip when your program raises
+selected exceptions.
+
+@table @code
+@kindex break exception
+@item break exception
+Set a breakpoint that trips whenever (any task in the) program raises
+any exception.
+
+@item break exception @var{name}
+Set a breakpoint that trips whenever (any task in the) program raises
+the exception @var{name}.
+
+When inserting a breakpoint on a specific exception for which an
+homonym entity exists in the application, it is necessary to prefix
+the exception name with its package name. In particular, if an entity
+sharing the same name as one of the standard exceptions has been defined,
+the exception name must be prefixed with package @code{Standard} when
+setting a breakpoint on this exception.
+
+@smallexample
+@iftex
+@leftskip=0.5cm
+@end iftex
+(gdb) break exception Standard.Constraint_Error
+@end smallexample
+
+@item break exception unhandled
+Set a breakpoint that trips whenever (any task in the) program raises an
+exception for which there is no handler.
+At the moment,
+depending on the implementation of exceptions used on your platform,
+this may not have quite the desired effect. Other forms of
+exception breaking stop the program at the point the exception is raised.
+In Ada implementations that use setjmp and longjmp to implement exception
+handling, however, unhandled exceptions are not detected until the
+affected task's stack is completely unwound. Thus, you find out that a
+task has terminated with an exception, but you aren't told where it was
+raised.
+
+@kindex info exceptions
+@item info exceptions
+@itemx info exceptions @var{regexp}
+The @code{info exceptions} command permits the user to examine all defined
+exceptions within Ada programs. With a regular expression, @var{regexp}, as
+argument, prints out only those exceptions whose name matches @var{regexp}.
+@end table
+
+@node Ada Generic Units
+@subsubsection Debugging Generic Units
+@cindex Ada, generic units
+
+GNAT always uses code expansion for generic instantiation. This means that
+each time an instantiation occurs, a complete copy of the original code is
+made with appropriate substitutions.
+
+It is not possible to refer to the original generic entities themselves
+in @value{GDBN} (there is no code to refer to), but it
+is certainly possible to debug a particular instance of a generic, simply by
+using the appropriate expanded names. For example, suppose that
+@code{Gen} is a generic package:
+
+@smallexample
+-- In file gen.ads:
+generic package Gen is
+ function F (v1 : Integer) return Integer;
+end Gen;
+
+-- In file gen.adb:
+package body Gen is
+ function F (v1 : Integer) return Integer is
+ begin
+ return v1+1; -- Line 5
+ end F;
+end Gen;
+@end smallexample
+
+@noindent
+and we have the following expansions
+
+@smallexample
+with Gen;
+procedure G is
+ package Gen1 is new Gen;
+ package Gen2 is new Gen;
+
+ I : Integer := 0;
+begin
+ I := Gen1.F (I);
+ I := Gen2.F (I);
+ I := Gen1.F (I);
+ I := Gen2.F (I);
+end;
+@end smallexample
+
+@noindent
+Then to break on a call to procedure @code{F} in the @code{Gen2} instance, simply
+use the command:
+
+@smallexample
+break G.Gen2.F
+@end smallexample
+
+When a breakpoint occurs, you can step through the code of the generic
+instance in the normal manner. You can also examine values of data in the
+normal manner, providing the appropriate generic package qualification to
+refer to non-local entities.
+
+@node Ada Glitches
+@subsubsection Known Peculiarities of Ada Mode
+@cindex Ada, problems
+
+Besides the omissions listed previously (@pxref{Omissions from Ada}),
+we know of several problems with and limitations of Ada mode in
+@value{GDBN},
+some of which will be fixed with planned future releases of the debugger
+and the GNU Ada compiler.
+
+@itemize @bullet
+@item
+Currently, the debugger
+has insufficient information to determine whether certain pointers represent
+pointers to objects or the objects themselves.
+Thus, the user may have to tack an extra @code{.all} after an expression
+to get it printed properly.
+
+@item
+Static constants that the compiler chooses not to materialize as objects in
+storage are invisible to the debugger.
+
+@item
+Named parameter associations in function argument lists are ignored (the
+argument lists are treated as positional).
+
+@item
+Many useful library packages are currently invisible to the debugger.
+
+@item
+Fixed-point arithmetic, conversions, input, and output is carried out using
+floating-point arithmetic, and may give results that only approximate those on
+the host machine.
+
+@item
+The type of the @t{'Address} attribute may not be @code{System.Address}.
+
+@item
+When stopped in a particular subprogram, you can access variables defined
+in other, lexically
+enclosing subprograms by their simple names. At the moment, however, this
+may not always work; it depends on whether the compiler happens to have
+made the necessary information (the ``static link'') available
+at execution time, which it can sometimes avoid. Of course,
+even in those cases where
+the compiler does not provide the information, you can still look at such
+variables by issuing the appropriate number of @code{up} commands to get to
+frame containing the variable you wish to see.
+Access to non-local variables does not, at the moment, work in
+the test expressions for conditional breakpoints
+(@pxref{Conditions, ,Break conditions}) unless you happen to specify these
+while stopped in the subprogram in which they are to be applied.
+
+@item
+Depending on the platform, it is not always possible to set breakpoints
+on nested functions by name (e.g., @code{break foo}). In effect, the
+nested functions act like local variables of the enclosing function.
+On these platforms, you must wait until @value{GDBN} is stopped in
+the enclosing function before using this form of @code{break} command.
+This is not much of a limitation, since you can still set a breakpoint on
+the first line of the desired function using the usual
+@code{break @var{file}:@var{line}} syntax.
+
+@item
+The GNAT compiler never generates the prefix @code{Standard} for any of
+the standard symbols defined by the Ada language. @value{GDBN} knows about
+this: it will strip the prefix from names when you use it, and will never
+look for a name you have so qualified among local symbols, nor match against
+symbols in other packages or subprograms. If you have
+defined entities anywhere in your program other than parameters and
+local variables whose simple names match names in @code{Standard},
+GNAT's lack of qualification here can cause confusion. When this happens,
+you can usually resolve the confusion
+by qualifying the problematic names with package
+@code{Standard} explicitly.
+@end itemize
+
@node Unsupported languages
@section Unsupported languages