std: Switch from libbacktrace to gimli

This commit is a proof-of-concept for switching the standard library's
backtrace symbolication mechanism on most platforms from libbacktrace to
gimli. The standard library's support for `RUST_BACKTRACE=1` requires
in-process parsing of object files and DWARF debug information to
interpret it and print the filename/line number of stack frames as part
of a backtrace.

Historically this support in the standard library has come from a
library called "libbacktrace". The libbacktrace library seems to have
been extracted from gcc at some point and is written in C. We've had a
lot of issues with libbacktrace over time, unfortunately, though. The
library does not appear to be actively maintained since we've had
patches sit for months-to-years without comments. We have discovered a
good number of soundness issues with the library itself, both when
parsing valid DWARF as well as invalid DWARF. This is enough of an issue
that the libs team has previously decided that we cannot feed untrusted
inputs to libbacktrace. This also doesn't take into account the
portability of libbacktrace which has been difficult to manage and
maintain over time. While possible there are lots of exceptions and it's
the main C dependency of the standard library right now.

For years it's been the desire to switch over to a Rust-based solution
for symbolicating backtraces. It's been assumed that we'll be using the
Gimli family of crates for this purpose, which are targeted at safely
and efficiently parsing DWARF debug information. I've been working
recently to shore up the Gimli support in the `backtrace` crate. As of a
few weeks ago the `backtrace` crate, by default, uses Gimli when loaded
from crates.io. This transition has gone well enough that I figured it
was time to start talking seriously about this change to the standard
library.

This commit is a preview of what's probably the best way to integrate
the `backtrace` crate into the standard library with the Gimli feature
turned on. While today it's used as a crates.io dependency, this commit
switches the `backtrace` crate to a submodule of this repository which
will need to be updated manually. This is not done lightly, but is
thought to be the best solution. The primary reason for this is that the
`backtrace` crate needs to do some pretty nontrivial filesystem
interactions to locate debug information. Working without `std::fs` is
not an option, and while it might be possible to do some sort of
trait-based solution when prototyped it was found to be too unergonomic.
Using a submodule allows the `backtrace` crate to build as a submodule
of the `std` crate itself, enabling it to use `std::fs` and such.

Otherwise this adds new dependencies to the standard library. This step
requires extra attention because this means that these crates are now
going to be included with all Rust programs by default. It's important
to note, however, that we're already shipping libbacktrace with all Rust
programs by default and it has a bunch of C code implementing all of
this internally anyway, so we're basically already switching
already-shipping functionality to Rust from C.

* `object` - this crate is used to parse object file headers and
  contents. Very low-level support is used from this crate and almost
  all of it is disabled. Largely we're just using struct definitions as
  well as convenience methods internally to read bytes and such.

* `addr2line` - this is the main meat of the implementation for
  symbolication. This crate depends on `gimli` for DWARF parsing and
  then provides interfaces needed by the `backtrace` crate to turn an
  address into a filename / line number. This crate is actually pretty
  small (fits in a single file almost!) and mirrors most of what
  `dwarf.c` does for libbacktrace.

* `miniz_oxide` - the libbacktrace crate transparently handles
  compressed debug information which is compressed with zlib. This crate
  is used to decompress compressed debug sections.

* `gimli` - not actually used directly, but a dependency of `addr2line`.

* `adler32`- not used directly either, but a dependency of
  `miniz_oxide`.

The goal of this change is to improve the safety of backtrace
symbolication in the standard library, especially in the face of
possibly malformed DWARF debug information. Even to this day we're still
seeing segfaults in libbacktrace which could possibly become security
vulnerabilities. This change should almost entirely eliminate this
possibility whilc also paving the way forward to adding more features
like split debug information.

Some references for those interested are:

* Original addition of libbacktrace - #12602
* OOM with libbacktrace - #24231
* Backtrace failure due to use of uninitialized value - #28447
* Possibility to feed untrusted data to libbacktrace - #21889
* Soundness fix for libbacktrace - #33729
* Crash in libbacktrace - #39468
* Support for macOS, never merged - ianlancetaylor/libbacktrace#2
* Performance issues with libbacktrace - #29293, #37477
* Update procedure is quite complicated due to how many patches we
  need to carry - #50955
* Libbacktrace doesn't work on MinGW with dynamic libs - #71060
* Segfault in libbacktrace on macOS - #71397

Switching to Rust will not make us immune to all of these issues. The
crashes are expected to go away, but correctness and performance may
still have bugs arise. The gimli and `backtrace` crates, however, are
actively maintained unlike libbacktrace, so this should enable us to at
least efficiently apply fixes as situations come up.

diff --git a/.gitmodules b/.gitmodules
index 2eae52b2eac54f3885b9847b200f68182c0ec2bb..a327aaa8d5a34501ae7c78625f95340cfbd77b06 100644 (file)
--- a/.gitmodules
+++ b/.gitmodules
@@ -44,3 +44,6 @@
 [submodule "src/tools/rust-analyzer"]
        path = src/tools/rust-analyzer
        url = https://github.com/rust-analyzer/rust-analyzer.git
+[submodule "library/backtrace"]
+       path = library/backtrace
+       url = https://github.com/rust-lang/backtrace-rs.git

diff --git a/Cargo.lock b/Cargo.lock
index d0ce581343f0b473871b99a208b8c28e0f115eb2..8e0621ad96fccb439d9a8deb81297d0c6197a3ac 100644 (file)
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,10 +1,26 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
 [[package]]
-name = "adler32"
-version = "1.0.3"
+name = "addr2line"
+version = "0.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7e522997b529f05601e05166c07ed17789691f562762c7f3b987263d2dedee5c"
+checksum = "1b6a2d3371669ab3ca9797670853d61402b03d0b4b9ebf33d677dfa720203072"
+dependencies = [
+ "compiler_builtins",
+ "gimli",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "adler"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee2a4ec343196209d6594e19543ae87a39f96d5534d7174822a3ad825dd6ed7e"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-core",
+]
 
 [[package]]
 name = "aho-corasick"
@@ -125,28 +141,14 @@ checksum = "f8aac770f1885fd7e387acedd76065302551364496e46b3dd00860b2f8359b9d"
 
 [[package]]
 name = "backtrace"
-version = "0.3.46"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b1e692897359247cc6bb902933361652380af0f1b7651ae5c5013407f30e109e"
+version = "0.3.50"
 dependencies = [
- "backtrace-sys",
+ "addr2line",
  "cfg-if",
- "compiler_builtins",
  "libc",
+ "miniz_oxide",
+ "object",
  "rustc-demangle",
- "rustc-std-workspace-core",
-]
-
-[[package]]
-name = "backtrace-sys"
-version = "0.1.37"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "18fbebbe1c9d1f383a9cc7e8ccdb471b91c8d024ee9c2ca5b5346121fe8b4399"
-dependencies = [
- "cc",
- "compiler_builtins",
- "libc",
- "rustc-std-workspace-core",
 ]
 
 [[package]]
@@ -688,9 +690,9 @@ dependencies = [
 
 [[package]]
 name = "crc32fast"
-version = "1.1.2"
+version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e91d5240c6975ef33aeb5f148f35275c25eda8e8a5f95abe421978b05b8bf192"
+checksum = "ba125de2af0df55319f41944744ad91c71113bf74a4646efff39afe1f6842db1"
 dependencies = [
  "cfg-if",
 ]
@@ -1023,9 +1025,9 @@ checksum = "37ab347416e802de484e4d03c7316c48f1ecb56574dfd4a46a80f173ce1de04d"
 
 [[package]]
 name = "flate2"
-version = "1.0.12"
+version = "1.0.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ad3c5233c9a940c8719031b423d7e6c16af66e031cb0420b0896f5245bf181d3"
+checksum = "68c90b0fc46cf89d227cc78b40e494ff81287a92dd07631e5af0d06fe3cf885e"
 dependencies = [
  "cfg-if",
  "crc32fast",
@@ -1159,6 +1161,17 @@ dependencies = [
  "wasi",
 ]
 
+[[package]]
+name = "gimli"
+version = "0.22.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aaf91faf136cb47367fa430cd46e37a788775e7fa104f8b4bcb3861dc389b724"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
 [[package]]
 name = "git2"
 version = "0.13.5"
@@ -1819,11 +1832,14 @@ dependencies = [
 
 [[package]]
 name = "miniz_oxide"
-version = "0.3.5"
+version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6f3f74f726ae935c3f514300cc6773a0c9492abc5e972d42ba0c0ebb88757625"
+checksum = "be0f75932c1f6cfae3c04000e40114adf955636e19040f9c0a2c380702aa1c7f"
 dependencies = [
- "adler32",
+ "adler",
+ "compiler_builtins",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
 ]
 
 [[package]]
@@ -1955,6 +1971,17 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "object"
+version = "0.20.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1ab52be62400ca80aa00285d25253d7f7c437b7375c4de678f5405d3afe82ca5"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
 [[package]]
 name = "once_cell"
 version = "1.1.0"
@@ -4347,8 +4374,8 @@ dependencies = [
 name = "std"
 version = "0.0.0"
 dependencies = [
+ "addr2line",
  "alloc",
- "backtrace",
  "cfg-if",
  "compiler_builtins",
  "core",
@@ -4357,10 +4384,13 @@ dependencies = [
  "hashbrown",
  "hermit-abi",
  "libc",
+ "miniz_oxide",
+ "object",
  "panic_abort",
  "panic_unwind",
  "profiler_builtins",
  "rand 0.7.3",
+ "rustc-demangle",
  "unwind",
  "wasi",
 ]

diff --git a/Cargo.toml b/Cargo.toml
index 4e49d697be1fb2dabcfb4e48e8b57010f4154acf..1936e35aa4c5d252e64a06244b4f869ed53352da 100644 (file)
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -56,6 +56,18 @@ overflow-checks = false
 # per-crate configuration isn't specifiable in the environment.
 codegen-units = 10000
 
+# These dependencies of the standard library implement symbolication for
+# backtraces on most platforms. Their debuginfo causes both linking to be slower
+# (more data to chew through) and binaries to be larger without really all that
+# much benefit. This section turns them all to down to have no debuginfo which
+# helps to improve link times a little bit.
+[profile.release.package]
+addr2line.debug = 0
+adler.debug = 0
+gimli.debug = 0
+miniz_oxide.debug = 0
+object.debug = 0
+
 # We want the RLS to use the version of Cargo that we've got vendored in this
 # repository to ensure that the same exact version of Cargo is used by both the
 # RLS and the Cargo binary itself. The RLS depends on Cargo as a git repository
@@ -80,5 +92,11 @@ rustc-std-workspace-core = { path = 'library/rustc-std-workspace-core' }
 rustc-std-workspace-alloc = { path = 'library/rustc-std-workspace-alloc' }
 rustc-std-workspace-std = { path = 'library/rustc-std-workspace-std' }
 
+# This crate's integration with libstd is a bit wonky, so we use a submodule
+# instead of a crates.io dependency. Make sure everything else in the repo is
+# also using the submodule, however, so we can avoid duplicate copies of the
+# source code for this crate.
+backtrace = { path = "library/backtrace" }
+
 [patch."https://github.com/rust-lang/rust-clippy"]
 clippy_lints = { path = "src/tools/clippy/clippy_lints" }

diff --git a/library/backtrace b/library/backtrace
new file mode 160000 (submodule)
index 0000000..4083a90
--- /dev/null
+++ b/library/backtrace
@@ -0,0 +1 @@
+Subproject commit 4083a90168d605b682ba166a0c01f86b3384e474

diff --git a/library/std/Cargo.toml b/library/std/Cargo.toml
index b4951488fd86ca411076aab9d426d59516afd25d..474765d8638116fd6b3740a32842b618fb4210a1 100644 (file)
--- a/library/std/Cargo.toml
+++ b/library/std/Cargo.toml
@@ -22,11 +22,15 @@ profiler_builtins = { path = "../profiler_builtins", optional = true }
 unwind = { path = "../unwind" }
 hashbrown = { version = "0.6.2", default-features = false, features = ['rustc-dep-of-std'] }
 
-[dependencies.backtrace_rs]
-package = "backtrace"
-version = "0.3.46"
-default-features = false # without the libstd `backtrace` feature, stub out everything
-features = [ "rustc-dep-of-std" ] # enable build support for integrating into libstd
+# Dependencies of the `backtrace` crate
+addr2line = { version = "0.13.0", optional = true, default-features = false }
+rustc-demangle = { version = "0.1.4", features = ['rustc-dep-of-std'] }
+miniz_oxide = { version = "0.4.0", optional = true, default-features = false }
+[dependencies.object]
+version = "0.20"
+optional = true
+default-features = false
+features = ['read_core', 'elf', 'macho', 'pe']
 
 [dev-dependencies]
 rand = "0.7"
@@ -45,11 +49,12 @@ wasi = { version = "0.9.0", features = ['rustc-dep-of-std'], default-features =
 
 [features]
 backtrace = [
-  "backtrace_rs/dbghelp",          # backtrace/symbolize on MSVC
-  "backtrace_rs/libbacktrace",     # symbolize on most platforms
-  "backtrace_rs/libunwind",        # backtrace on most platforms
-  "backtrace_rs/dladdr",           # symbolize on platforms w/o libbacktrace
+  "gimli-symbolize",
+  'addr2line/rustc-dep-of-std',
+  'object/rustc-dep-of-std',
+  'miniz_oxide/rustc-dep-of-std',
 ]
+gimli-symbolize = []
 
 panic-unwind = ["panic_unwind"]
 profiler = ["profiler_builtins"]

diff --git a/library/std/build.rs b/library/std/build.rs
index 43a3327d84b613905ad8c65daaf9ab52ff181633..83073cc77dd1a12354ce6b9e535804e83f33e27e 100644 (file)
--- a/library/std/build.rs
+++ b/library/std/build.rs
@@ -88,4 +88,5 @@ fn main() {
         println!("cargo:rustc-cfg=feature=\"restricted-std\"");
     }
     println!("cargo:rustc-env=STD_ENV_ARCH={}", env::var("CARGO_CFG_TARGET_ARCH").unwrap());
+    println!("cargo:rustc-cfg=backtrace_in_libstd");
 }

diff --git a/library/std/src/backtrace.rs b/library/std/src/backtrace.rs
index 02e6811bc3f4357e33b732e17f138925562a31f7..09f83ea5fca81c5eb42c2fa9dfd4218933699c1e 100644 (file)
--- a/library/std/src/backtrace.rs
+++ b/library/std/src/backtrace.rs
@@ -91,6 +91,7 @@
 // `Backtrace`, but that's a relatively small price to pay relative to capturing
 // a backtrace or actually symbolizing it.
 
+use crate::backtrace_rs::{self, BytesOrWideString};
 use crate::env;
 use crate::ffi::c_void;
 use crate::fmt;
@@ -98,8 +99,6 @@
 use crate::sync::Mutex;
 use crate::sys_common::backtrace::{lock, output_filename};
 use crate::vec::Vec;
-use backtrace::BytesOrWideString;
-use backtrace_rs as backtrace;
 
 /// A captured OS thread stack backtrace.
 ///
@@ -150,7 +149,7 @@ struct BacktraceFrame {
 }
 
 enum RawFrame {
-    Actual(backtrace::Frame),
+    Actual(backtrace_rs::Frame),
     #[cfg(test)]
     Fake,
 }
@@ -197,7 +196,7 @@ impl fmt::Debug for BacktraceSymbol {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(fmt, "{{ ")?;
 
-        if let Some(fn_name) = self.name.as_ref().map(|b| backtrace::SymbolName::new(b)) {
+        if let Some(fn_name) = self.name.as_ref().map(|b| backtrace_rs::SymbolName::new(b)) {
             write!(fmt, "fn: \"{:#}\"", fn_name)?;
         } else {
             write!(fmt, "fn: <unknown>")?;
@@ -223,7 +222,7 @@ fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
                 BytesOrWide::Bytes(w) => BytesOrWideString::Bytes(w),
                 BytesOrWide::Wide(w) => BytesOrWideString::Wide(w),
             },
-            backtrace::PrintFmt::Short,
+            backtrace_rs::PrintFmt::Short,
             crate::env::current_dir().as_ref().ok(),
         )
     }
@@ -305,7 +304,7 @@ fn create(ip: usize) -> Backtrace {
         let mut frames = Vec::new();
         let mut actual_start = None;
         unsafe {
-            backtrace::trace_unsynchronized(|frame| {
+            backtrace_rs::trace_unsynchronized(|frame| {
                 frames.push(BacktraceFrame {
                     frame: RawFrame::Actual(frame.clone()),
                     symbols: Vec::new(),
@@ -356,9 +355,9 @@ fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
 
         let full = fmt.alternate();
         let (frames, style) = if full {
-            (&capture.frames[..], backtrace::PrintFmt::Full)
+            (&capture.frames[..], backtrace_rs::PrintFmt::Full)
         } else {
-            (&capture.frames[capture.actual_start..], backtrace::PrintFmt::Short)
+            (&capture.frames[capture.actual_start..], backtrace_rs::PrintFmt::Short)
         };
 
         // When printing paths we try to strip the cwd if it exists, otherwise
@@ -370,7 +369,7 @@ fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
             output_filename(fmt, path, style, cwd.as_ref().ok())
         };
 
-        let mut f = backtrace::BacktraceFmt::new(fmt, style, &mut print_path);
+        let mut f = backtrace_rs::BacktraceFmt::new(fmt, style, &mut print_path);
         f.add_context()?;
         for frame in frames {
             let mut f = f.frame();
@@ -380,7 +379,7 @@ fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
                 for symbol in frame.symbols.iter() {
                     f.print_raw(
                         frame.frame.ip(),
-                        symbol.name.as_ref().map(|b| backtrace::SymbolName::new(b)),
+                        symbol.name.as_ref().map(|b| backtrace_rs::SymbolName::new(b)),
                         symbol.filename.as_ref().map(|b| match b {
                             BytesOrWide::Bytes(w) => BytesOrWideString::Bytes(w),
                             BytesOrWide::Wide(w) => BytesOrWideString::Wide(w),
@@ -415,7 +414,7 @@ fn resolve(&mut self) {
                 RawFrame::Fake => unimplemented!(),
             };
             unsafe {
-                backtrace::resolve_frame_unsynchronized(frame, |symbol| {
+                backtrace_rs::resolve_frame_unsynchronized(frame, |symbol| {
                     symbols.push(BacktraceSymbol {
                         name: symbol.name().map(|m| m.as_bytes().to_vec()),
                         filename: symbol.filename_raw().map(|b| match b {

diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index c6e5b0a492ac815711ed25414ddfe6a7b7c47028..30e1514a8b8306cd28f6842b5e98243e8bb3c9a6 100644 (file)
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -511,6 +511,10 @@ pub mod task {
 // compiler
 pub mod rt;
 
+#[path = "../../backtrace/src/lib.rs"]
+#[allow(dead_code, unused_attributes)]
+mod backtrace_rs;
+
 // Pull in the `std_detect` crate directly into libstd. The contents of
 // `std_detect` are in a different repository: rust-lang/stdarch.
 //

diff --git a/library/std/src/panicking.rs b/library/std/src/panicking.rs
index 9542e7209b4cf168347e18b00cc3253c349fb020..ab2a60103069d6571179c20c565f5e64800d6f0b 100644 (file)
--- a/library/std/src/panicking.rs
+++ b/library/std/src/panicking.rs
@@ -171,7 +171,7 @@ fn default_hook(info: &PanicInfo<'_>) {
     // If this is a double panic, make sure that we print a backtrace
     // for this panic. Otherwise only print it if logging is enabled.
     let backtrace_env = if panic_count::get() >= 2 {
-        RustBacktrace::Print(backtrace_rs::PrintFmt::Full)
+        RustBacktrace::Print(crate::backtrace_rs::PrintFmt::Full)
     } else {
         backtrace::rust_backtrace_env()
     };

diff --git a/library/std/src/sys_common/backtrace.rs b/library/std/src/sys_common/backtrace.rs
index e9b1e86d7ae49ed8e66a6f5a995be65ceb8ef4d5..d386a656e4ffdc896aa93fdceb53060d1c75a71c 100644 (file)
--- a/library/std/src/sys_common/backtrace.rs
+++ b/library/std/src/sys_common/backtrace.rs
@@ -1,3 +1,4 @@
+use crate::backtrace_rs::{self, BacktraceFmt, BytesOrWideString, PrintFmt};
 use crate::borrow::Cow;
 /// Common code for printing the backtrace in the same way across the different
 /// supported platforms.
@@ -9,8 +10,6 @@
 use crate::sync::atomic::{self, Ordering};
 use crate::sys::mutex::Mutex;
 
-use backtrace_rs::{BacktraceFmt, BytesOrWideString, PrintFmt};
-
 /// Max number of frames to print.
 const MAX_NB_FRAMES: usize = 100;
 

diff --git a/rustfmt.toml b/rustfmt.toml
index cb689098f8989c24f6bdde40edae6f1b5ac787cd..26cdcfff2a316a5ff80d20ee544b30b639d2e7cb 100644 (file)
--- a/rustfmt.toml
+++ b/rustfmt.toml
@@ -14,6 +14,7 @@ ignore = [
     "src/test",
 
     # do not format submodules
+    "library/backtrace",
     "library/stdarch",
     "src/doc/book",
     "src/doc/edition-guide",

diff --git a/src/bootstrap/dist.rs b/src/bootstrap/dist.rs
index 7f10d7895a5e75688265ee905251a823e96098b0..a4a1d5193b9b9b3ff1e010e7c9a5020ef687aaae 100644 (file)
--- a/src/bootstrap/dist.rs
+++ b/src/bootstrap/dist.rs
@@ -1016,7 +1016,17 @@ fn run(self, builder: &Builder<'_>) -> PathBuf {
         let src_files = ["Cargo.lock"];
         // This is the reduced set of paths which will become the rust-src component
         // (essentially libstd and all of its path dependencies).
-        copy_src_dirs(builder, &builder.src, &["library"], &[], &dst_src);
+        copy_src_dirs(
+            builder,
+            &builder.src,
+            &["library"],
+            &[
+                // not needed and contains symlinks which rustup currently
+                // chokes on when unpacking.
+                "library/backtrace/crates",
+            ],
+            &dst_src,
+        );
         for file in src_files.iter() {
             builder.copy(&builder.src.join(file), &dst_src.join(file));
         }

diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs
index 56d2717c30477913881d71d70770f4f7f0a72a56..8769d5e17bb3ec96291435ce0f0e84382b59eb99 100644 (file)
--- a/src/tools/tidy/src/deps.rs
+++ b/src/tools/tidy/src/deps.rs
@@ -17,6 +17,7 @@
     "MIT",
     "Unlicense/MIT",
     "Unlicense OR MIT",
+    "0BSD OR MIT OR Apache-2.0", // adler license
 ];
 
 /// These are exceptions to Rust's permissive licensing policy, and
@@ -36,7 +37,6 @@
     ("ryu", "Apache-2.0 OR BSL-1.0"),       // rls/cargo/... (because of serde)
     ("bytesize", "Apache-2.0"),             // cargo
     ("im-rc", "MPL-2.0+"),                  // cargo
-    ("adler32", "BSD-3-Clause AND Zlib"),   // cargo dep that isn't used
     ("constant_time_eq", "CC0-1.0"),        // rustfmt
     ("sized-chunks", "MPL-2.0+"),           // cargo via im-rc
     ("bitmaps", "MPL-2.0+"),                // cargo via im-rc
@@ -57,7 +57,8 @@
 /// This list is here to provide a speed-bump to adding a new dependency to
 /// rustc. Please check with the compiler team before adding an entry.
 const PERMITTED_DEPENDENCIES: &[&str] = &[
-    "adler32",
+    "addr2line",
+    "adler",
     "aho-corasick",
     "annotate-snippets",
     "ansi_term",
@@ -65,7 +66,6 @@
     "atty",
     "autocfg",
     "backtrace",
-    "backtrace-sys",
     "bitflags",
     "block-buffer",
     "block-padding",
@@ -98,6 +98,7 @@
     "generic-array",
     "getopts",
     "getrandom",
+    "gimli",
     "hashbrown",
     "hermit-abi",
     "humantime",
@@ -119,6 +120,7 @@
     "miniz_oxide",
     "nodrop",
     "num_cpus",
+    "object",
     "once_cell",
     "opaque-debug",
     "parking_lot",

diff --git a/src/tools/tidy/src/lib.rs b/src/tools/tidy/src/lib.rs
index 08b2fccd73f5cfcf325142695db070587429dd86..19218cbd66a8a59d65c94dfb84303ed03d7eec33 100644 (file)
--- a/src/tools/tidy/src/lib.rs
+++ b/src/tools/tidy/src/lib.rs
@@ -51,6 +51,7 @@ macro_rules! tidy_error {
 fn filter_dirs(path: &Path) -> bool {
     let skip = [
         "src/llvm-project",
+        "library/backtrace",
         "library/stdarch",
         "src/tools/cargo",
         "src/tools/clippy",