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@@ -0,0 +1,136 @@
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+ From FEDORA_PATCHES Mon Sep 17 00:00:00 2001
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+ From: Tom Tromey <tromey@adacore.com>
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+ Date: Fri, 24 Feb 2023 10:40:16 -0700
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+ Subject: gdb-rhbz2183595-rustc-inside_main.patch
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+
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+ ;; Backport "Fix crash in inside_main_func"
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+ ;; (Tom Tromey, RHBZ 2183595)
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+
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+ gdb 13.1 crashes while running the rust compiler's debugger tests.
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+ The crash has a number of causes.
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+
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+ First, the rust compiler still uses the C++-like _Z mangling, but with
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+ its own twist -- some hex digits added to the end of a symbol. So,
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+ while gdb finds the correct name of "main":
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+
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+ (top-gdb) p name
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+ $13 = 0x292e0c0 "rustc_gdb_1031745::main"
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+
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+ It isn't found in the minsyms, because C++ demangling yields:
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+
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+ [99] t 0x90c0 _ZN17rustc_gdb_10317454main17h5b5be7fe16a97225E section .text rustc_gdb_1031745::main::h5b5be7fe16a97225 zko06yobckx336v
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+
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+ This could perhaps be fixed. I also filed a new PR to suggest
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+ preferring the linkage name of the main program.
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+
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+ Next, the rust compiler emits both a DW_TAG_subprogram and a
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+ DW_TAG_namespace for "main". This happens because the file is named
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+ "main.rs" -- i.e., the bug is specific to the source file name. The
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+ crash also seems to require the nested function inside of 'main', at
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+ least for me. The namespace always is generated, but perhaps this
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+ changes the ordering in the DWARF.
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+
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+ When inside_main_func looks up the main symbol, it finds the namespace
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+ symbol rather than the function. (I filed a bug about fixing gdb's
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+ symbol tables -- long overdue.)
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+
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+ Meanwhile, as I think it's important to fix this crash sooner rather
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+ than later, this patch changes inside_main_func to check that the
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+ symbol that is found is LOC_BLOCK. This perhaps should have been done
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+ in the first place, anyway.
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+
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+ Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30158
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+
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+ diff --git a/gdb/frame.c b/gdb/frame.c
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+ --- a/gdb/frame.c
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+ +++ b/gdb/frame.c
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+ @@ -2453,6 +2453,14 @@ inside_main_func (frame_info_ptr this_frame)
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+ if (bs.symbol == nullptr)
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+ return false;
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+
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+ + /* We might have found some unrelated symbol. For example, the
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+ + Rust compiler can emit both a subprogram and a namespace with
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+ + the same name in the same scope; and due to how gdb's symbol
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+ + tables currently work, we can't request the one we'd
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+ + prefer. */
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+ + if (bs.symbol->aclass () != LOC_BLOCK)
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+ + return false;
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+ +
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+ const struct block *block = bs.symbol->value_block ();
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+ gdb_assert (block != nullptr);
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+ sym_addr = block->start ();
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+ diff --git a/gdb/testsuite/gdb.rust/main-crash.exp b/gdb/testsuite/gdb.rust/main-crash.exp
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+ new file mode 100644
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+ --- /dev/null
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+ +++ b/gdb/testsuite/gdb.rust/main-crash.exp
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+ @@ -0,0 +1,35 @@
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+ +# Copyright (C) 2023 Free Software Foundation, Inc.
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+ +
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+ +# This program is free software; you can redistribute it and/or modify
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+ +# it under the terms of the GNU General Public License as published by
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+ +# the Free Software Foundation; either version 3 of the License, or
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+ +# (at your option) any later version.
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+ +#
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+ +# This program is distributed in the hope that it will be useful,
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+ +# but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ +# GNU General Public License for more details.
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+ +#
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+ +# You should have received a copy of the GNU General Public License
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+ +# along with this program. If not, see <http://www.gnu.org/licenses/>.
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+ +
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+ +# Regression test for a crash in inside_main_func.
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+ +
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+ +load_lib rust-support.exp
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+ +require allow_rust_tests
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+ +
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+ +standard_testfile main.rs
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+ +if {[prepare_for_testing "failed to prepare" $testfile $srcfile \
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+ + {debug rust}]} {
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+ + return -1
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+ +}
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+ +
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+ +set line [gdb_get_line_number "BREAK"]
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+ +# The bug was that this would crash.
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+ +if {![runto ${srcfile}:$line]} {
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+ + untested "could not run to breakpoint"
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+ + return -1
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+ +}
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+ +
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+ +# Test that gdb is alive.
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+ +gdb_test "print 23" " = 23"
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+ diff --git a/gdb/testsuite/gdb.rust/main.rs b/gdb/testsuite/gdb.rust/main.rs
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+ new file mode 100644
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+ --- /dev/null
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+ +++ b/gdb/testsuite/gdb.rust/main.rs
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+ @@ -0,0 +1,30 @@
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+ +// Copyright (C) 2016-2023 Free Software Foundation, Inc.
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+ +
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+ +// This program is free software; you can redistribute it and/or modify
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+ +// it under the terms of the GNU General Public License as published by
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+ +// the Free Software Foundation; either version 3 of the License, or
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+ +// (at your option) any later version.
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+ +//
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+ +// This program is distributed in the hope that it will be useful,
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+ +// but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ +// GNU General Public License for more details.
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+ +//
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+ +// You should have received a copy of the GNU General Public License
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+ +// along with this program. If not, see <http://www.gnu.org/licenses/>.
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+ +
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+ +#![allow(dead_code)]
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+ +#![allow(unused_variables)]
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+ +#![allow(unused_assignments)]
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+ +
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+ +fn global_fn(x: u8) {
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+ + // BREAK
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+ +}
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+ +
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+ +fn main() {
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+ + fn nested(y: u8) {
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+ + global_fn(y)
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+ + }
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+ +
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+ + nested(23);
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+ +}
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keiths
commented a year ago
Resolves: rhbz#2183595