fix(trim-paths): explicit remap to current dir .

On macOS in https://github.com/rust-lang/rust/blob/87e1447aa/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs#L856
when `work_dir` is remapped to an empty string,
LLVM won't generate any `N_SO` and `N_OSO` symbols,
resulting in corrupted debuginfo.

This commit fixes that by always appending an explicit `.`
when `--remap-path-prefix` remaps to relative workspace root.

Also, `SO` symbols should be remapped correctly.

src/cargo/core/compiler/mod.rs

@@ -1230,7 +1230,7 @@ fn trim_paths_args(
         // * path dependencies outside workspace root directory
         if is_local && pkg_root.strip_prefix(ws_root).is_ok() {
             remap.push(ws_root);
-            remap.push("="); // empty to remap to relative paths.
+            remap.push("=."); // explicitly remap to cwd (rustc working dir).
         } else {
             remap.push(pkg_root);
             remap.push("=");

tests/testsuite/profile_trim_paths.rs

@@ -83,7 +83,7 @@ fn release_profile_default_to_object() {
 [COMPILING] foo v0.0.1 ([CWD])
 [RUNNING] `rustc [..]\
     -Zremap-path-scope=object \
-    --remap-path-prefix=[CWD]= \
+    --remap-path-prefix=[CWD]=. \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]
 [FINISHED] release [..]",
         )
@@ -121,7 +121,7 @@ fn one_option() {
 [COMPILING] foo v0.0.1 ([CWD])
 [RUNNING] `rustc [..]\
     -Zremap-path-scope={option} \
-    --remap-path-prefix=[CWD]= \
+    --remap-path-prefix=[CWD]=. \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]
 [FINISHED] dev [..]",
             ))
@@ -158,7 +158,7 @@ fn multiple_options() {
 [COMPILING] foo v0.0.1 ([CWD])
 [RUNNING] `rustc [..]\
     -Zremap-path-scope=diagnostics,macro,object \
-    --remap-path-prefix=[CWD]= \
+    --remap-path-prefix=[CWD]=. \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]
 [FINISHED] dev [..]",
         )
@@ -193,7 +193,7 @@ fn profile_merge_works() {
 [COMPILING] foo v0.0.1 ([CWD])
 [RUNNING] `rustc [..]\
     -Zremap-path-scope=diagnostics \
-    --remap-path-prefix=[CWD]= \
+    --remap-path-prefix=[CWD]=. \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]
 [FINISHED] custom [..]",
         )
@@ -243,7 +243,7 @@ fn registry_dependency() {
 [COMPILING] foo v0.0.1 ([CWD])
 [RUNNING] `rustc [..]\
     -Zremap-path-scope=object \
-    --remap-path-prefix=[CWD]= \
+    --remap-path-prefix=[CWD]=. \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]
 [FINISHED] dev [..]
 [RUNNING] `target/debug/foo[EXE]`"
@@ -297,7 +297,7 @@ fn git_dependency() {
 [COMPILING] foo v0.0.1 ([CWD])
 [RUNNING] `rustc [..]\
     -Zremap-path-scope=object \
-    --remap-path-prefix=[CWD]= \
+    --remap-path-prefix=[CWD]=. \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]
 [FINISHED] dev [..]
 [RUNNING] `target/debug/foo[EXE]`"
@@ -338,12 +338,12 @@ fn path_dependency() {
 [COMPILING] bar v0.0.1 ([..]/cocktail-bar)
 [RUNNING] `rustc [..]\
     -Zremap-path-scope=object \
-    --remap-path-prefix=[CWD]= \
+    --remap-path-prefix=[CWD]=. \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]
 [COMPILING] foo v0.0.1 ([CWD])
 [RUNNING] `rustc [..]\
     -Zremap-path-scope=object \
-    --remap-path-prefix=[CWD]= \
+    --remap-path-prefix=[CWD]=. \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]
 [FINISHED] dev [..]
 [RUNNING] `target/debug/foo[EXE]`"
@@ -392,7 +392,7 @@ fn path_dependency_outside_workspace() {
 [COMPILING] foo v0.0.1 ([CWD])
 [RUNNING] `rustc [..]\
     -Zremap-path-scope=object \
-    --remap-path-prefix=[CWD]= \
+    --remap-path-prefix=[CWD]=. \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]
 [FINISHED] dev [..]
 [RUNNING] `target/debug/foo[EXE]`"
@@ -446,7 +446,7 @@ fn diagnostics_works() {
             "\
 [RUNNING] [..]rustc [..]\
     -Zremap-path-scope=diagnostics \
-    --remap-path-prefix=[CWD]= \
+    --remap-path-prefix=[CWD]=. \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]",
         )
         .run();
@@ -479,12 +479,10 @@ fn object_works() {
 }
 
 fn object_works_helper(run: impl Fn(&std::path::Path) -> Vec<u8>) {
-    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_bytes = registry_src.as_os_str().as_encoded_bytes();
 
     Package::new("bar", "0.0.1")
         .file("Cargo.toml", &basic_manifest("bar", "0.0.1"))
@@ -507,7 +505,7 @@ fn object_works_helper(run: impl Fn(&std::path::Path) -> Vec<u8>) {
         .build();
 
     let pkg_root = p.root();
-    let pkg_root = pkg_root.as_os_str().as_bytes();
+    let pkg_root = pkg_root.as_os_str().as_encoded_bytes();
 
     p.cargo("build").run();
 
@@ -549,7 +547,7 @@ fn object_works_helper(run: impl Fn(&std::path::Path) -> Vec<u8>) {
 [COMPILING] foo v0.0.1 ([CWD])
 [RUNNING] `rustc [..]\
     -Zremap-path-scope=object \
-    --remap-path-prefix=[CWD]= \
+    --remap-path-prefix=[CWD]=. \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]
 [FINISHED] dev [..]",
         ))
@@ -577,7 +575,7 @@ fn object_works_helper(run: impl Fn(&std::path::Path) -> Vec<u8>) {
             // on macOS `SO` symbols are embedded in final binaries and should be trimmed.
             // See rust-lang/rust#117652.
             assert!(
-                memchr::memmem::find(line, b" SO ").is_some(),
+                memchr::memmem::find(line, b" SO ").is_none(),
                 "untrimmed `SO` symbol found"
             )
         }
@@ -699,7 +697,7 @@ fn lldb_works_after_trimmed() {
             "\
 [RUNNING] `rustc [..]\
     -Zremap-path-scope=object \
-    --remap-path-prefix=[CWD]= \
+    --remap-path-prefix=[CWD]=. \
     --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]",
         )
         .run();