fix(trim-paths): remap common prefix only

New remap rules for git/registry dependencies:

* Git dependencies: remove ~/.cargo/git/checkouts prefix.
* Registry dependencies: remove ~/.cargo/registry/src prefix.

This make the remap rules fixed to a finite number,
minimizing the burden for users to configure debuggers.

src/cargo/core/compiler/mod.rs

@@ -1217,18 +1217,22 @@ fn trim_paths_args(
     let package_remap = {
         let pkg_root = unit.pkg.root();
         let ws_root = cx.bcx.ws.root();
-        let is_local = unit.pkg.package_id().source_id().is_path();
         let mut remap = OsString::from("--remap-path-prefix=");
-        // Remapped to path relative to workspace root:
+        // Remap rules for dependencies
         //
-        // * path dependencies under workspace root directory
-        //
-        // Remapped to `<pkg>-<version>`
-        //
-        // * registry dependencies
-        // * git dependencies
-        // * path dependencies outside workspace root directory
-        if is_local && pkg_root.strip_prefix(ws_root).is_ok() {
+        // * Git dependencies: remove ~/.cargo/git/checkouts prefix.
+        // * Registry dependencies: remove ~/.cargo/registry/src prefix.
+        // * Others (e.g. path dependencies):
+        //     * relative paths to workspace root if inside the workspace directory.
+        //     * otherwise remapped to `<pkg>-<version>`.
+        let source_id = unit.pkg.package_id().source_id();
+        if source_id.is_git() {
+            remap.push(cx.bcx.config.git_checkouts_path().as_path_unlocked());
+            remap.push("=");
+        } else if source_id.is_registry() {
+            remap.push(cx.bcx.config.registry_source_path().as_path_unlocked());
+            remap.push("=");
+        } else if pkg_root.strip_prefix(ws_root).is_ok() {
             remap.push(ws_root);
             remap.push("=."); // remap to relative rustc work dir explicitly
         } else {

tests/testsuite/profile_trim_paths.rs

@@ -225,11 +225,11 @@ fn registry_dependency() {
         .build();
 
     let registry_src = paths::home().join(".cargo/registry/src");
-    let pkg_remap = format!("{}/[..]/bar-0.0.1=bar-0.0.1", registry_src.display());
+    let registry_src = registry_src.display();
 
     p.cargo("run --verbose -Ztrim-paths")
         .masquerade_as_nightly_cargo(&["-Ztrim-paths"])
-        .with_stdout("bar-0.0.1/src/lib.rs")
+        .with_stdout("-[..]/bar-0.0.1/src/lib.rs") // Omit the hash of Source URL
         .with_stderr(&format!(
             "\
 [UPDATING] [..]
@@ -238,7 +238,7 @@ fn registry_dependency() {
 [COMPILING] bar v0.0.1
 [RUNNING] `rustc [..]\
     -Zremap-path-scope=object \
-    --remap-path-prefix={pkg_remap} \
+    --remap-path-prefix={registry_src}= \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]
 [COMPILING] foo v0.0.1 ([CWD])
 [RUNNING] `rustc [..]\
@@ -281,18 +281,18 @@ fn git_dependency() {
         .build();
 
     let git_checkouts_src = paths::home().join(".cargo/git/checkouts");
-    let pkg_remap = format!("{}/bar-[..]/[..]=bar-0.0.1", git_checkouts_src.display());
+    let git_checkouts_src = git_checkouts_src.display();
 
     p.cargo("run --verbose -Ztrim-paths")
         .masquerade_as_nightly_cargo(&["-Ztrim-paths"])
-        .with_stdout("bar-0.0.1/src/lib.rs")
+        .with_stdout("bar-[..]/[..]/src/lib.rs") // Omit the hash of Source URL and commit
         .with_stderr(&format!(
             "\
 [UPDATING] git repository `{url}`
 [COMPILING] bar v0.0.1 ({url}[..])
 [RUNNING] `rustc [..]\
     -Zremap-path-scope=object \
-    --remap-path-prefix={pkg_remap} \
+    --remap-path-prefix={git_checkouts_src}= \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]
 [COMPILING] foo v0.0.1 ([CWD])
 [RUNNING] `rustc [..]\
@@ -426,7 +426,6 @@ fn diagnostics_works() {
 
     let registry_src = paths::home().join(".cargo/registry/src");
     let registry_src = registry_src.display();
-    let pkg_remap = format!("{registry_src}/[..]/bar-0.0.1=bar-0.0.1");
 
     p.cargo("build -vv -Ztrim-paths")
         .masquerade_as_nightly_cargo(&["-Ztrim-paths"])
@@ -439,7 +438,7 @@ fn diagnostics_works() {
             "\
 [RUNNING] [..]rustc [..]\
     -Zremap-path-scope=diagnostics \
-    --remap-path-prefix={pkg_remap} \
+    --remap-path-prefix={registry_src}= \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]",
         ))
         .with_stderr_contains(
@@ -516,9 +515,9 @@ fn object_works_helper(split_debuginfo: &str, run: impl Fn(&std::path::Path) ->
     use std::os::unix::ffi::OsStrExt;
 
     let registry_src = paths::home().join(".cargo/registry/src");
-    let pkg_remap = format!("{}/[..]/bar-0.0.1=bar-0.0.1", registry_src.display());
-    let rust_src = "/lib/rustc/src/rust".as_bytes();
     let registry_src_bytes = registry_src.as_os_str().as_bytes();
+    let registry_src = registry_src.display();
+    let rust_src = "/lib/rustc/src/rust".as_bytes();
 
     Package::new("bar", "0.0.1")
         .file("Cargo.toml", &basic_manifest("bar", "0.0.1"))
@@ -570,7 +569,7 @@ fn object_works_helper(split_debuginfo: &str, run: impl Fn(&std::path::Path) ->
 [COMPILING] bar v0.0.1
 [RUNNING] `rustc [..]-C split-debuginfo={split_debuginfo} [..]\
     -Zremap-path-scope=object \
-    --remap-path-prefix={pkg_remap} \
+    --remap-path-prefix={registry_src}= \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]
 [COMPILING] foo v0.0.1 ([CWD])
 [RUNNING] `rustc [..]-C split-debuginfo={split_debuginfo} [..]\