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* [binutils-gdb] [gdb/exp] Fix cast handling for indirection
@ 2024-05-03 7:36 Tom de Vries
0 siblings, 0 replies; only message in thread
From: Tom de Vries @ 2024-05-03 7:36 UTC (permalink / raw)
To: gdb-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ed8fd0a342f6e832fee1a3fabc3e494977780dcf
commit ed8fd0a342f6e832fee1a3fabc3e494977780dcf
Author: Tom de Vries <tdevries@suse.de>
Date: Fri May 3 09:37:19 2024 +0200
[gdb/exp] Fix cast handling for indirection
Consider a test-case compiled without debug info, containing:
...
char a = 'a';
char *
a_loc (void)
{
return &a;
}
...
We get:
...
(gdb) p (char)*a_loc ()
Cannot access memory at address 0x10
...
There's a bug in unop_ind_base_operation::evaluate that evaluates
"(char)*a_loc ()" the same as:
...
(gdb) p (char)*(char)a_loc ()
Cannot access memory at address 0x10
...
Fix this by instead evaluating it the same as:
...
(gdb) p (char)*(char *)a_loc ()
$1 = 97 'a'
...
Tested on x86_64-linux.
PR exp/31693
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31693
Diff:
---
gdb/expop.h | 8 +++---
gdb/testsuite/gdb.base/cast-indirection.c | 31 ++++++++++++++++++++++
gdb/testsuite/gdb.base/cast-indirection.exp | 40 +++++++++++++++++++++++++++++
3 files changed, 76 insertions(+), 3 deletions(-)
diff --git a/gdb/expop.h b/gdb/expop.h
index b81e228c07e..1967d9779b7 100644
--- a/gdb/expop.h
+++ b/gdb/expop.h
@@ -1513,9 +1513,11 @@ public:
struct expression *exp,
enum noside noside) override
{
- if (expect_type != nullptr && expect_type->code () == TYPE_CODE_PTR)
- expect_type = check_typedef (expect_type)->target_type ();
- value *val = std::get<0> (m_storage)->evaluate (expect_type, exp, noside);
+ struct type *pointer_to_expect_type = (expect_type != nullptr
+ ? lookup_pointer_type (expect_type)
+ : nullptr);
+ value *val
+ = std::get<0> (m_storage)->evaluate (pointer_to_expect_type, exp, noside);
return eval_op_ind (expect_type, exp, noside, val);
}
diff --git a/gdb/testsuite/gdb.base/cast-indirection.c b/gdb/testsuite/gdb.base/cast-indirection.c
new file mode 100644
index 00000000000..d59c66ead35
--- /dev/null
+++ b/gdb/testsuite/gdb.base/cast-indirection.c
@@ -0,0 +1,31 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2024 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/>. */
+
+char a = 'a';
+
+char *
+a_loc (void)
+{
+ return &a;
+}
+
+int
+main (void)
+{
+ int res = *a_loc () == 'a';
+ return !res;
+}
diff --git a/gdb/testsuite/gdb.base/cast-indirection.exp b/gdb/testsuite/gdb.base/cast-indirection.exp
new file mode 100644
index 00000000000..d2c6d58e3ca
--- /dev/null
+++ b/gdb/testsuite/gdb.base/cast-indirection.exp
@@ -0,0 +1,40 @@
+# Copyright (C) 2024 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/>.
+
+# Check that "p (char)*a_loc ()" is handled as "p (char)*(char *)a_loc ()".
+
+standard_testfile
+
+if { [prepare_for_testing "failed to prepare" $testfile $srcfile \
+ {nodebug}] == -1} {
+ return -1
+}
+
+if ![runto_main] {
+ return -1
+}
+
+gdb_test "p a_loc ()" \
+ "'a_loc' has unknown return type; cast the call to its declared return type"
+
+gdb_test "p *a_loc ()" \
+ "'a_loc' has unknown return type; cast the call to its declared return type"
+
+gdb_test "p *(char *)a_loc ()" " = 97 'a'"
+
+gdb_test "p (char)*(char *)a_loc ()" " = 97 'a'"
+
+# Regression test for PR31693.
+gdb_test "p (char)*a_loc ()" " = 97 'a'"
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