Don't use mmap on macOS

.github/workflows/main.yml

@@ -78,6 +78,7 @@ jobs:
     - run: cargo test --no-default-features --features "dbghelp std"
     - run: cargo test --no-default-features --features "dbghelp std verify-winapi"
     - run: cargo test --manifest-path crates/cpp_smoke_test/Cargo.toml
+    - run: cargo test --manifest-path crates/macos_frames_test/Cargo.toml
     - run: cargo test --features libbacktrace --manifest-path crates/without_debuginfo/Cargo.toml
     - run: cargo test --features "libbacktrace coresymbolication" --manifest-path crates/without_debuginfo/Cargo.toml
     - run: cargo test --features "libbacktrace gimli-symbolize" --manifest-path crates/without_debuginfo/Cargo.toml

Cargo.toml

@@ -16,7 +16,7 @@ edition = "2018"
 
 [workspace]
 members = ['crates/cpp_smoke_test']
-exclude = ['crates/without_debuginfo']
+exclude = ['crates/without_debuginfo', 'crates/macos_frames_test']
 
 [dependencies]
 cfg-if = "0.1.10"

crates/backtrace-sys/build.rs

@@ -36,7 +36,9 @@ fn main() {
 
     // `mmap` does not exist on Windows, so we use
     // the less efficient `read`-based code.
-    if target.contains("windows") {
+    // Using `mmap` on macOS causes weird isseus - see
+    // https://github.com/rust-lang/rust/pull/45866
+    if target.contains("windows") || target.contains("darwin") {
         build.file("src/libbacktrace/read.c");
     } else {
         build.file("src/libbacktrace/mmapio.c");

crates/macos_frames_test/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "macos_frames_test"
+version = "0.1.0"
+authors = ["Aaron Hill <[email protected]>"]
+edition = "2018"
+
+[dependencies.backtrace]
+path = "../.."

crates/macos_frames_test/src/lib.rs

@@ -0,0 +1 @@
+// intentionally blank

crates/macos_frames_test/tests/main.rs

@@ -0,0 +1,30 @@
+// Based on from https://github.com/rust-lang/rust/blob/2cb0b8582ebbf9784db9cec06fff517badbf4553/src/test/ui/issues/issue-45731.rs
+// This needs to go in a crate by itself, since it modifies the dSYM for the entire test
+// output directory.
+//
+// Note that this crate is *not* part of the overall `backtrace-rs` workspace,
+// so that it gets its own 'target' directory. We manually invoke this test
+// in .github/workflows/main.yml by passing `--manifest-path` to Cargo
+#[test]
+#[cfg(target_os = "macos")]
+fn backtrace_no_dsym() {
+    use std::{env, fs, panic};
+
+    // Find our dSYM and replace the DWARF binary with an empty file
+    let mut dsym_path = env::current_exe().unwrap();
+    let executable_name = dsym_path.file_name().unwrap().to_str().unwrap().to_string();
+    assert!(dsym_path.pop()); // Pop executable
+    dsym_path.push(format!(
+        "{}.dSYM/Contents/Resources/DWARF/{0}",
+        executable_name
+    ));
+    let _ = fs::OpenOptions::new()
+        .read(false)
+        .write(true)
+        .truncate(true)
+        .create(false)
+        .open(&dsym_path)
+        .unwrap();
+
+    backtrace::Backtrace::new();
+}