debuginfo: slices are DW_TAG_array_type's by shua · Pull Request #153238 · rust-lang/rust

shua · 2026-03-01T02:13:35Z

Rust debuginfo for unsized structs with embedded slice types is lacking, and it makes it difficult for debuggers to correctly print types like Rc<str> (eg #114195). Specifically, these three structs would have essentially the same debug info (modulo some names):

struct Foo { a: u32, s: str } // unsized
struct Bar { a: u32, s: [u8] } // unsized
struct Baz { a: u32, s: u8 }

This changes how the compiler generates debuginfo in this case, and I used existing compilers (gcc, clang) handling of C flexible member arrays as a reference.

rustbot · 2026-03-01T02:13:40Z

r? @davidtwco

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shua · 2026-03-01T13:55:18Z

another relevant thread from gdb bugtracker about rust's weird unsized type debug info and some related fixes in gdb: https://sourceware.org/bugzilla/show_bug.cgi?id=30330 . The type of change here (changing slice types to be array types with no count, similar to C's VLA/FMA) was discussed but I guess never implemented in rustc?

davidtwco

Could you also add a codegen-llvm test for the debuginfo?

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shua · 2026-05-06T06:45:29Z

@rustbot ready

davidtwco · 2026-05-15T12:50:39Z

@bors r+

rust-bors · 2026-05-15T12:50:42Z

📌 Commit f398585 has been approved by davidtwco

It is now in the queue for this repository.

debuginfo: slices are DW_TAG_array_type's Rust debuginfo for unsized structs with embedded slice types is lacking, and it makes it difficult for debuggers to correctly print types like `Rc<str>` (eg rust-lang#114195). Specifically, these three structs would have essentially the same debug info (modulo some names): ```rust struct Foo { a: u32, s: str } // unsized struct Bar { a: u32, s: [u8] } // unsized struct Baz { a: u32, s: u8 } ``` This changes how the compiler generates debuginfo in this case, and I used existing compilers (gcc, clang) handling of C flexible member arrays as a reference.

Rollup of 11 pull requests Successful merges: - #148788 (Unconstrained parameter fix) - #153238 (debuginfo: slices are DW_TAG_array_type's) - #155521 (Add lint againts invalid runtime symbol definitions) - #156319 (Require EIIs to be defined when we compile a rust dylib) - #156452 (Implement pinned drop sugar) - #156600 (Make const param default test reproduce original ICE) - #156493 (actually run the temp_dir doctest) - #156556 (Require UTF-8 in `Utf8Pattern::StringPattern`) - #156565 (delegation: emit error when self type is not specified and accessed) - #156586 (Use DropCtxt::new_block and new_block_with_statements systematically.) - #156587 (Correctly handle associated items in rustdoc macro expansion)

debuginfo: slices are DW_TAG_array_type's Rust debuginfo for unsized structs with embedded slice types is lacking, and it makes it difficult for debuggers to correctly print types like `Rc<str>` (eg rust-lang#114195). Specifically, these three structs would have essentially the same debug info (modulo some names): ```rust struct Foo { a: u32, s: str } // unsized struct Bar { a: u32, s: [u8] } // unsized struct Baz { a: u32, s: u8 } ``` This changes how the compiler generates debuginfo in this case, and I used existing compilers (gcc, clang) handling of C flexible member arrays as a reference.

…uwer Rollup of 12 pull requests Successful merges: - #153238 (debuginfo: slices are DW_TAG_array_type's) - #156319 (Require EIIs to be defined when we compile a rust dylib) - #156452 (Implement pinned drop sugar) - #156554 (Allow user-provided `llvm_args` to override target spec arguments) - #156571 (Disable `main_needs_argc_argv` for Wasm) - #156600 (Make const param default test reproduce original ICE) - #156493 (actually run the temp_dir doctest) - #156556 (Require UTF-8 in `Utf8Pattern::StringPattern`) - #156565 (delegation: emit error when self type is not specified and accessed) - #156586 (Use DropCtxt::new_block and new_block_with_statements systematically.) - #156587 (Correctly handle associated items in rustdoc macro expansion) - #156604 (coverage: Reduce and clarify the context-mismatch test case)

JonathanBrouwer · 2026-05-15T18:10:46Z

@bors r-
#156613 (comment)

rust-bors · 2026-05-15T18:10:53Z

This pull request was unapproved.

This PR was contained in a rollup (#156613), which was unapproved.

View changes since this unapproval

rustbot · 2026-05-16T08:38:47Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

shua · 2026-05-16T08:41:30Z

Is there a way to run the tests that failed in the rollup PR (auto - aarch64-msvc-1, try - x86_64-mingw-1, try - x86_64-msvc-1) on this PR? I think I fixed the issue, but I'm not able to check msvc compile targets on my machine.

JonathanBrouwer · 2026-05-16T08:47:43Z

@bors try jobs=aarch64-msvc-1,x86_64-mingw-1,x86_64-msvc-1

debuginfo: slices are DW_TAG_array_type's try-job: aarch64-msvc-1 try-job: x86_64-mingw-1 try-job: x86_64-msvc-1

shua · 2026-05-16T10:30:12Z

@bors try jobs=aarch64-msvc-1,x86_64-mingw-1,x86_64-msvc-1

rust-bors · 2026-05-16T10:30:15Z

@shua: 🔑 Insufficient privileges: not in try users

JonathanBrouwer · 2026-05-16T10:30:51Z

@bors try jobs=aarch64-msvc-1,x86_64-mingw-1,x86_64-msvc-1

debuginfo: slices are DW_TAG_array_type's try-job: aarch64-msvc-1 try-job: x86_64-mingw-1 try-job: x86_64-msvc-1

rust-log-analyzer · 2026-05-16T12:30:45Z

The job x86_64-mingw-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)


---- [debuginfo-gdb] tests\debuginfo\strings-and-strs.rs stdout ----
NOTE: compiletest thinks it is using GDB version 14002000

error: check directive(s) from `D:\a\rust\rust\tests\debuginfo\strings-and-strs.rs` not found in debugger output. errors:
    (strings-and-strs.rs:30) `$7 = alloc::rc::Rc<str, alloc::alloc::Global> {ptr: core::ptr::non_null::NonNull<alloc::rc::RcInner<str>> {pointer: alloc::rc::RcInner<str> {strong: core::cell::Cell<usize> {value: core::cell::UnsafeCell<usize> {value: 1}}, weak: core::cell::Cell<usize> {value: core::cell::UnsafeCell<usize> {value: 1}}, value: 0x[...]}}, phantom: core::marker::PhantomData<alloc::rc::RcInner<str>>, alloc: alloc::alloc::Global}`
the following subset of check directive(s) was found successfully:
    (strings-and-strs.rs:12) `$1 = alloc::string::String {vec: alloc::vec::Vec<u8, alloc::alloc::Global> {buf: alloc::raw_vec::RawVec<u8, alloc::alloc::Global> {inner: alloc::raw_vec::RawVecInner<alloc::alloc::Global> {ptr: core::ptr::unique::Unique<u8> {pointer: core::ptr::non_null::NonNull<u8> {pointer: 0x6a5df0}, _marker: core::marker::PhantomData<u8>}, cap: core::num::niche_types::UsizeNoHighBit (5), alloc: alloc::alloc::Global}, _marker: core::marker::PhantomData<u8>}, len: 5}}`
    (strings-and-strs.rs:15) `$2 = "Hello"`
    (strings-and-strs.rs:18) `$3 = strings_and_strs::Foo {inner: "Hello"}`
    (strings-and-strs.rs:21) `$4 = ("Hello", "World")`
    (strings-and-strs.rs:24) `$5 = alloc::rc::Rc<&str, alloc::alloc::Global> {ptr: core::ptr::non_null::NonNull<alloc::rc::RcInner<&str>> {pointer: 0x6a8fd0}, phantom: core::marker::PhantomData<alloc::rc::RcInner<&str>>, alloc: alloc::alloc::Global}`
    (strings-and-strs.rs:27) `$6 = alloc::boxed::Box<str, alloc::alloc::Global> [87, 111, 114, 108, 100]`
status: exit code: 0
command: PATH="D:\a\rust\rust\build\x86_64-pc-windows-gnu\stage2\lib\rustlib\x86_64-pc-windows-gnu\lib;D:\a\rust\rust\build\x86_64-pc-windows-gnu\bootstrap-tools\x86_64-pc-windows-gnu\release\deps;D:\a\rust\rust\ninja;D:\a\rust\rust\mingw64\bin;C:\msys64\usr\bin;D:\a\rust\rust\sccache;C:\Program Files\MongoDB\Server\7.0\bin;C:\vcpkg;C:\tools\zstd;C:\hostedtoolcache\windows\stack\3.9.3\x64;C:\cabal\bin;C:\ghcup\bin;C:\mingw64\bin;C:\Program Files\dotnet;C:\Program Files\MySQL\MySQL Server 8.0\bin;C:\Program Files\R\R-4.6.0\bin\x64;C:\SeleniumWebDrivers\GeckoDriver;C:\SeleniumWebDrivers\EdgeDriver;C:\SeleniumWebDrivers\ChromeDriver;C:\Program Files (x86)\sbt\bin;C:\Program Files (x86)\GitHub CLI;C:\Program Files\Git\bin;C:\Program Files (x86)\pipx_bin;C:\npm\prefix;C:\hostedtoolcache\windows\go\1.24.13\x64\bin;C:\hostedtoolcache\windows\Python\3.12.10\x64\Scripts;C:\hostedtoolcache\windows\Python\3.12.10\x64;C:\hostedtoolcache\windows\Ruby\3.3.11\x64\bin;C:\Program Files\OpenSSL\bin;C:\tools\kotlinc\bin;C:\hostedtoolcache\windows\Java_Temurin-Hotspot_jdk\17.0.19-10\x64\bin;C:\Program Files\ImageMagick-7.1.2-Q16-HDRI;C:\Program Files\Microsoft SDKs\Azure\CLI2\wbin;C:\ProgramData\kind;C:\ProgramData\Chocolatey\bin;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0;C:\Windows\System32\OpenSSH;C:\Program Files\PowerShell\7;C:\Program Files\Microsoft\Web Platform Installer;C:\Program Files\Microsoft SQL Server\Client SDK\ODBC\170\Tools\Binn;C:\Program Files\Microsoft SQL Server\150\Tools\Binn;C:\Program Files\dotnet;C:\Program Files (x86)\Windows Kits\10\Windows Performance Toolkit;C:\Program Files (x86)\WiX Toolset v3.14\bin;C:\Program Files\Microsoft SQL Server\130\DTS\Binn;C:\Program Files\Microsoft SQL Server\140\DTS\Binn;C:\Program Files\Microsoft SQL Server\150\DTS\Binn;C:\Program Files\Microsoft SQL Server\160\DTS\Binn;C:\Program Files\Microsoft SQL Server\170\DTS\Binn;C:\ProgramData\chocolatey\lib\pulumi\tools\Pulumi\bin;C:\Program Files\CMake\bin;C:\Strawberry\c\bin;C:\Strawberry\perl\site\bin;C:\Strawberry\perl\bin;C:\ProgramData\chocolatey\lib\maven\apache-maven-3.9.15\bin;C:\Program Files\Microsoft Service Fabric\bin\Fabric\Fabric.Code;C:\Program Files\Microsoft SDKs\Service Fabric\Tools\ServiceFabricLocalClusterManager;C:\Program Files\nodejs;C:\Program Files\Git\cmd;C:\Program Files\Git\mingw64\bin;C:\Program Files\Git\usr\bin;C:\Program Files\GitHub CLI;C:\tools\php;C:\Program Files (x86)\sbt\bin;C:\Program Files\Amazon\AWSCLIV2;C:\Program Files\Amazon\SessionManagerPlugin\bin;C:\Program Files\Amazon\AWSSAMCLI\bin;C:\Program Files\Microsoft SQL Server\130\Tools\Binn;C:\Program Files\mongosh;C:\Program Files\LLVM\bin;C:\Program Files (x86)\LLVM\bin;C:\Users\runneradmin\.dotnet\tools;C:\Users\runneradmin\.cargo\bin;C:\Users\runneradmin\AppData\Local\Microsoft\WindowsApps" "D:\\a\\rust\\rust\\mingw64\\bin\\gdb" "-quiet" "-batch" "-nx" "-command=D:\\a\\rust\\rust\\build\\x86_64-pc-windows-gnu\\test\\debuginfo\\strings-and-strs.gdb\\strings-and-strs.debugger.script"
--- stdout -------------------------------
GNU gdb (GDB) 14.2
Copyright (C) 2023 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-w64-mingw32".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word".
Breakpoint 1 at 0x140001f67: file tests\debuginfo/strings-and-strs.rs, line 70.

Breakpoint 1, strings_and_strs::main () at tests\debuginfo/strings-and-strs.rs:70
70     zzz(); // #break
$1 = alloc::string::String {vec: alloc::vec::Vec<u8, alloc::alloc::Global> {buf: alloc::raw_vec::RawVec<u8, alloc::alloc::Global> {inner: alloc::raw_vec::RawVecInner<alloc::alloc::Global> {ptr: core::ptr::unique::Unique<u8> {pointer: core::ptr::non_null::NonNull<u8> {pointer: 0x6a5df0}, _marker: core::marker::PhantomData<u8>}, cap: core::num::niche_types::UsizeNoHighBit (5), alloc: alloc::alloc::Global}, _marker: core::marker::PhantomData<u8>}, len: 5}}
$2 = "Hello"
$3 = strings_and_strs::Foo {inner: "Hello"}
$4 = ("Hello", "World")
$5 = alloc::rc::Rc<&str, alloc::alloc::Global> {ptr: core::ptr::non_null::NonNull<alloc::rc::RcInner<&str>> {pointer: 0x6a8fd0}, phantom: core::marker::PhantomData<alloc::rc::RcInner<&str>>, alloc: alloc::alloc::Global}
$6 = alloc::boxed::Box<str, alloc::alloc::Global> [87, 111, 114, 108, 100]
$7 = alloc::rc::Rc<str, alloc::alloc::Global> {ptr: core::ptr::non_null::NonNull<alloc::rc::RcInner<str>> {pointer: *const alloc::rc::RcInner<str> [alloc::rc::RcInner<str> {strong: core::cell::Cell<usize> {value: core::cell::UnsafeCell<usize> {value: 1}}, weak: core::cell::Cell<usize> {value: core::cell::UnsafeCell<usize> {value: 1}}, value: 0x6a48f0}, alloc::rc::RcInner<str> {strong: core::cell::Cell<usize> {value: core::cell::UnsafeCell<usize> {value: 13451671976132374359}}, weak: core::cell::Cell<usize> {value: core::cell::UnsafeCell<usize> {value: 12370169555311111083}}, value: 0x6a4900}, alloc::rc::RcInner<str> {strong: core::cell::Cell<usize> {value: core::cell::UnsafeCell<usize> {value: 12370169555311111083}}, weak: core::cell::Cell<usize> {value: core::cell::UnsafeCell<usize> {value: 18369900232523579118}}, value: 0x6a4910}, alloc::rc::RcInner<str> {strong: core::cell::Cell<usize> {value: core::cell::UnsafeCell<usize> {value: 0}}, weak: core::cell::Cell<usize> {value: core::cell::UnsafeCell<usize> {value: 0}}, value: 0x6a4920}, alloc::rc::RcInner<str> {strong: core::cell::Cell<usize> {value: core::cell::UnsafeCell<usize> {value: 18369900232523579118}}, weak: core::cell::Cell<usize> {value: core::cell::UnsafeCell<usize> {value: 266956156054182}}, value: 0x6a4930}]}, phantom: core::marker::PhantomData<alloc::rc::RcInner<str>>, alloc: alloc::alloc::Global}
A debugging session is active.

 Inferior 1 [process 7404] will be killed.

Quit anyway? (y or n) [answered Y; input not from terminal]
------------------------------------------
stderr: none

---- [debuginfo-gdb] tests\debuginfo\strings-and-strs.rs stdout end ----

---

Some tests failed in compiletest suite=debuginfo mode=debuginfo host=x86_64-pc-windows-gnu target=x86_64-pc-windows-gnu
Bootstrap failed while executing `test --stage 2 --skip=compiler --skip=src`
Build completed unsuccessfully in 1:52:07
make: *** [Makefile:126: ci-mingw-x] Error 1
  local time: Sat May 16 12:30:20 CUT 2026
  network time: Sat, 16 May 2026 12:30:21 GMT
##[error]Process completed with exit code 2.
##[group]Run echo "disk usage:"
echo "disk usage:"

rust-bors · 2026-05-16T13:09:40Z

💔 Test for 2468142 failed: CI. Failed job:

try - x86_64-mingw-1 (web logs, enhanced plaintext logs)

rustbot assigned davidtwco Mar 1, 2026

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Zalathar mentioned this pull request May 15, 2026

Rollup of 11 pull requests #156610

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Rollup of 12 pull requests #156613

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debuginfo: slices are DW_TAG_array_type's

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Auto merge of #153238 - shua:lldb-rcstr, r=<try>

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debuginfo: slices are DW_TAG_array_type's try-job: aarch64-msvc-1 try-job: x86_64-mingw-1 try-job: x86_64-msvc-1

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adding debuginfo tests for str repr llvm di

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rust-bors Bot pushed a commit that referenced this pull request May 16, 2026

Auto merge of #153238 - shua:lldb-rcstr, r=<try>

2468142

debuginfo: slices are DW_TAG_array_type's try-job: aarch64-msvc-1 try-job: x86_64-mingw-1 try-job: x86_64-msvc-1

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