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(Ada) fix "error in expression" when using watch -location command

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The "watch -l EXPR" command with the language set to Ada currently
fails with the following error:

     (gdb) watch -l global_var
     Error in expression, near ` 0x000000000062d2d8'.

The error occurs because GDB internally translate the request into
a watchpoint on a different expression: "* (TYPE *) ADDR" where
TYPE and ADDR are the type and the address of the object returned
by the expression's evaluation (resp.). So, in the example above,
global_var being an integer stored at 0x000000000062d2d8, GDB tries
to set a watchpoint on "* (integer *) 0x000000000062d2d8", which
fails, because we try to parse this expression with Ada, when
in fact it is not valid.

This patch fixes the issue by implementing the la_watch_location_expression
language method, using a syntax that the Ada parser recognizes
("{TYPE} ADDR").

gdb/ChangeLog:

	* ada-lang.c (ada_watch_location_expression): New function.
        (ada_language_defn): Set la_watch_location_expression to
        ada_watch_location_expression.

gdb/testsuite/ChangeLog:

        * gdb.ada/watch_minus_l: New testcase.
This commit is contained in:
Joel Brobecker 2018-11-01 15:15:41 -07:00
parent 8b578f9c76
commit e2b7af7242
7 changed files with 129 additions and 1 deletions
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13
gdb/ada-lang.c
View file

@ -565,6 +565,17 @@ ada_print_array_index (struct value *index_value, struct ui_file *stream,
fprintf_filtered (stream, " => ");
}
/* la_watch_location_expression for Ada. */
gdb::unique_xmalloc_ptr<char>
ada_watch_location_expression (struct type *type, CORE_ADDR addr)
{
type = check_typedef (TYPE_TARGET_TYPE (check_typedef (type)));
std::string name = type_to_string (type);
return gdb::unique_xmalloc_ptr<char>
(xstrprintf ("{%s} %s", name.c_str (), core_addr_to_string (addr)));
}
/* Assuming VECT points to an array of *SIZE objects of size
ELEMENT_SIZE, grow it to contain at least MIN_SIZE objects,
updating *SIZE as necessary and returning the (new) array. */
@ -14425,7 +14436,7 @@ extern const struct language_defn ada_language_defn = {
ada_print_array_index,
default_pass_by_reference,
c_get_string,
c_watch_location_expression,
ada_watch_location_expression,
ada_get_symbol_name_matcher, /* la_get_symbol_name_matcher */
ada_iterate_over_symbols,
default_search_name_hash,