Auto merge of #112597 - danakj:map-linker-paths, r=michaelwoerister

Use the relative sysroot path in the linker command line to specify sysroot rlibs

This addresses #112586

Author: bors

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -5,7 +5,7 @@ use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::memmap::Mmap;
 use rustc_data_structures::temp_dir::MaybeTempDir;
 use rustc_errors::{ErrorGuaranteed, Handler};
-use rustc_fs_util::fix_windows_verbatim_for_gcc;
+use rustc_fs_util::{fix_windows_verbatim_for_gcc, try_canonicalize};
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_metadata::find_native_static_library;
 use rustc_metadata::fs::{copy_to_stdout, emit_wrapper_file, METADATA_FILENAME};
@@ -2682,6 +2682,30 @@ fn add_upstream_native_libraries(
     }
 }
 
+// Rehome lib paths (which exclude the library file name) that point into the sysroot lib directory
+// to be relative to the sysroot directory, which may be a relative path specified by the user.
+//
+// If the sysroot is a relative path, and the sysroot libs are specified as an absolute path, the
+// linker command line can be non-deterministic due to the paths including the current working
+// directory. The linker command line needs to be deterministic since it appears inside the PDB
+// file generated by the MSVC linker. See https://github.com/rust-lang/rust/issues/112586.
+//
+// The returned path will always have `fix_windows_verbatim_for_gcc()` applied to it.
+fn rehome_sysroot_lib_dir<'a>(sess: &'a Session, lib_dir: &Path) -> PathBuf {
+    let sysroot_lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
+    let canonical_sysroot_lib_path =
+        { try_canonicalize(&sysroot_lib_path).unwrap_or_else(|_| sysroot_lib_path.clone()) };
+
+    let canonical_lib_dir = try_canonicalize(lib_dir).unwrap_or_else(|_| lib_dir.to_path_buf());
+    if canonical_lib_dir == canonical_sysroot_lib_path {
+        // This path, returned by `target_filesearch().get_lib_path()`, has
+        // already had `fix_windows_verbatim_for_gcc()` applied if needed.
+        sysroot_lib_path
+    } else {
+        fix_windows_verbatim_for_gcc(&lib_dir)
+    }
+}
+
 // Adds the static "rlib" versions of all crates to the command line.
 // There's a bit of magic which happens here specifically related to LTO,
 // namely that we remove upstream object files.
@@ -2713,7 +2737,13 @@ fn add_static_crate<'a>(
     let cratepath = &src.rlib.as_ref().unwrap().0;
 
     let mut link_upstream = |path: &Path| {
-        cmd.link_rlib(&fix_windows_verbatim_for_gcc(path));
+        let rlib_path = if let Some(dir) = path.parent() {
+            let file_name = path.file_name().expect("rlib path has no file name path component");
+            rehome_sysroot_lib_dir(sess, &dir).join(file_name)
+        } else {
+            fix_windows_verbatim_for_gcc(path)
+        };
+        cmd.link_rlib(&rlib_path);
     };
 
     if !are_upstream_rust_objects_already_included(sess)
@@ -2782,7 +2812,7 @@ fn add_dynamic_crate(cmd: &mut dyn Linker, sess: &Session, cratepath: &Path) {
     // what its name is
     let parent = cratepath.parent();
     if let Some(dir) = parent {
-        cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
+        cmd.include_path(&rehome_sysroot_lib_dir(sess, dir));
     }
     let stem = cratepath.file_stem().unwrap().to_str().unwrap();
     // Convert library file-stem into a cc -l argument.