gdb: Additions to Ada
15.4.10.3 Additions to Ada
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As it does for other languages, GDB makes certain generic extensions to
Ada (
Expressions):
* If the expression E is a variable residing in memory (typically a
local variable or array element) and N is a positive integer, then
'E@N' displays the values of E and the 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.
* 'B::VAR' means "the variable named VAR that appears in function or
file B." When B is a file name, you must typically surround it in
single quotes.
* The expression '{TYPE} ADDR' means "the variable of type TYPE that
appears at address ADDR."
* A name starting with '$' is a convenience variable (
Convenience Vars) or a machine register (Registers).
In addition, GDB provides a few other shortcuts and outright
additions specific to Ada:
* The assignment statement is allowed as an expression, returning its
right-hand operand as its value. Thus, you may enter
(gdb) set x := y + 3
(gdb) print A(tmp := y + 1)
* 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:
(gdb) break f
(gdb) condition 1 (report(i); k += 1; A(k) > 100)
* 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 '["XX"]' within a string or
character literal denotes the (single) character whose numeric
encoding is XX in hexadecimal. The sequence of characters '["""]'
also denotes a single quotation mark in strings. For example,
"One line.["0a"]Next line.["0a"]"
contains an ASCII newline character ('Ada.Characters.Latin_1.LF')
after each period.
* The subtype used as a prefix for the attributes 'Pos, 'Min, and
'Max is optional (and is ignored in any case). For example, it is
valid to write
(gdb) print 'max(x, y)
* When printing arrays, GDB 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
(3 => 10, 17, 1)
That is, in contrast to valid Ada, only the first component has a
'=>' clause.
* 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 a'len, a'gth, or a'lh in
place of a'length.
* 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,
(gdb) print <JMPBUF_SAVE>[0]
* 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.
Info Catalog
gdb: Omissions from Ada
gdb: Ada
gdb: Overloading support for Ada