Auto merge of #6891 - ehuss:uplift-mac-dsym-example, r=alexcrichton

Symlink dSYM on macOS example binaries.

Examples previously ended up with a layout such as:

```
target/debug/examples/ex1
target/debug/examples/ex1.d
target/debug/examples/ex1-966e505ad4696130
target/debug/examples/ex1-966e505ad4696130.d
target/debug/examples/ex1-966e505ad4696130.dSYM/…
```

If you attempt to run lldb on the executable without the hash (`target/debug/examples/ex1`), then symbols could not be found. This PR solves this by creating a symlink from `ex1.dSYM -> ex1-966e505ad4696130.dSYM`.

Closes #6889

src/cargo/core/compiler/build_context/target_info.rs

@@ -225,12 +225,16 @@ impl TargetInfo {
         }
 
         // See rust-lang/cargo#4490, rust-lang/cargo#4960.
-        //  - Only uplift debuginfo for binaries.
-        //    Tests are run directly from `target/debug/deps/`
-        //    and examples are inside target/debug/examples/ which already have symbols next to them,
-        //    so no need to do anything.
-        if *kind == TargetKind::Bin {
-            if target_triple.contains("-apple-") {
+        // Only uplift debuginfo for binaries.
+        // - Tests are run directly from `target/debug/deps/` with the
+        //   metadata hash still in the filename.
+        // - Examples are only uplifted for apple because the symbol file
+        //   needs to match the executable file name to be found (i.e., it
+        //   needs to remove the hash in the filename). On Windows, the path
+        //   to the .pdb with the hash is embedded in the executable.
+        let is_apple = target_triple.contains("-apple-");
+        if *kind == TargetKind::Bin || (*kind == TargetKind::ExampleBin && is_apple) {
+            if is_apple {
                 ret.push(FileType {
                     suffix: ".dSYM".to_string(),
                     prefix: prefix.clone(),

tests/testsuite/build.rs

@@ -4132,10 +4132,8 @@ fn building_a_dependent_crate_witout_bin_should_fail() {
 }
 
 #[test]
+#[cfg(any(target_os = "macos", target_os = "ios"))]
 fn uplift_dsym_of_bin_on_mac() {
-    if !cfg!(any(target_os = "macos", target_os = "ios")) {
-        return;
-    }
     let p = project()
         .file("src/main.rs", "fn main() { panic!(); }")
         .file("src/bin/b.rs", "fn main() { panic!(); }")
@@ -4144,23 +4142,17 @@ fn uplift_dsym_of_bin_on_mac() {
         .build();
 
     p.cargo("build --bins --examples --tests").run();
-    assert!(p.bin("foo.dSYM").is_dir());
-    assert!(p.bin("b.dSYM").is_dir());
-    assert!(p
-        .bin("b.dSYM")
-        .symlink_metadata()
-        .expect("read metadata from b.dSYM")
-        .file_type()
-        .is_symlink());
-    assert!(!p.bin("c.dSYM").is_dir());
-    assert!(!p.bin("d.dSYM").is_dir());
+    assert!(p.target_debug_dir().join("foo.dSYM").is_dir());
+    assert!(p.target_debug_dir().join("b.dSYM").is_dir());
+    assert!(p.target_debug_dir().join("b.dSYM").is_symlink());
+    assert!(p.target_debug_dir().join("examples/c.dSYM").is_symlink());
+    assert!(!p.target_debug_dir().join("c.dSYM").exists());
+    assert!(!p.target_debug_dir().join("d.dSYM").exists());
 }
 
 #[test]
+#[cfg(all(target_os = "windows", target_env = "msvc"))]
 fn uplift_pdb_of_bin_on_windows() {
-    if !cfg!(all(target_os = "windows", target_env = "msvc")) {
-        return;
-    }
     let p = project()
         .file("src/main.rs", "fn main() { panic!(); }")
         .file("src/bin/b.rs", "fn main() { panic!(); }")
@@ -4171,8 +4163,10 @@ fn uplift_pdb_of_bin_on_windows() {
     p.cargo("build --bins --examples --tests").run();
     assert!(p.target_debug_dir().join("foo.pdb").is_file());
     assert!(p.target_debug_dir().join("b.pdb").is_file());
-    assert!(!p.target_debug_dir().join("c.pdb").is_file());
-    assert!(!p.target_debug_dir().join("d.pdb").is_file());
+    assert!(!p.target_debug_dir().join("examples/c.pdb").exists());
+    assert_eq!(p.glob("target/debug/examples/c-*.pdb").count(), 1);
+    assert!(!p.target_debug_dir().join("c.pdb").exists());
+    assert!(!p.target_debug_dir().join("d.pdb").exists());
 }
 
 // Ensure that `cargo build` chooses the correct profile for building

tests/testsuite/support/paths.rs

@@ -70,6 +70,8 @@ pub trait CargoPathExt {
     fn move_in_time<F>(&self, travel_amount: F)
     where
         F: Fn(i64, u32) -> (i64, u32);
+
+    fn is_symlink(&self) -> bool;
 }
 
 impl CargoPathExt for Path {
@@ -142,6 +144,10 @@ impl CargoPathExt for Path {
             });
         }
     }
+
+    fn is_symlink(&self) -> bool {
+        fs::symlink_metadata(self).map(|m| m.file_type().is_symlink()).unwrap_or(false)
+    }
 }
 
 fn do_op<F>(path: &Path, desc: &str, mut f: F)