Auto merge of #98098 - bjorn3:archive_refactor, r=michaelwoerister

Remove the source archive functionality of ArchiveWriter

We now build archives through strictly additive means rather than taking an existing archive and potentially substracting parts. This is simpler and makes it easier to swap out the archive writer in rust-lang/rust#97485.

Author: bors

Diff for: src/archive.rs

@@ -30,50 +30,19 @@ pub(crate) struct ArArchiveBuilder<'a> {
 }
 
 impl<'a> ArchiveBuilder<'a> for ArArchiveBuilder<'a> {
-    fn new(sess: &'a Session, output: &Path, input: Option<&Path>) -> Self {
-        let (src_archives, entries) = if let Some(input) = input {
-            let read_cache = ReadCache::new(File::open(input).unwrap());
-            let archive = ArchiveFile::parse(&read_cache).unwrap();
-            let mut entries = Vec::new();
-
-            for entry in archive.members() {
-                let entry = entry.unwrap();
-                entries.push((
-                    entry.name().to_vec(),
-                    ArchiveEntry::FromArchive { archive_index: 0, file_range: entry.file_range() },
-                ));
-            }
-
-            (vec![read_cache.into_inner()], entries)
-        } else {
-            (vec![], Vec::new())
-        };
-
+    fn new(sess: &'a Session, output: &Path) -> Self {
         ArArchiveBuilder {
             sess,
             dst: output.to_path_buf(),
             use_gnu_style_archive: sess.target.archive_format == "gnu",
             // FIXME fix builtin ranlib on macOS
             no_builtin_ranlib: sess.target.is_like_osx,
 
-            src_archives,
-            entries,
+            src_archives: vec![],
+            entries: vec![],
         }
     }
 
-    fn src_files(&mut self) -> Vec<String> {
-        self.entries.iter().map(|(name, _)| String::from_utf8(name.clone()).unwrap()).collect()
-    }
-
-    fn remove_file(&mut self, name: &str) {
-        let index = self
-            .entries
-            .iter()
-            .position(|(entry_name, _)| entry_name == name.as_bytes())
-            .expect("Tried to remove file not existing in src archive");
-        self.entries.remove(index);
-    }
-
     fn add_file(&mut self, file: &Path) {
         self.entries.push((
             file.file_name().unwrap().to_str().unwrap().to_string().into_bytes(),
@@ -105,7 +74,7 @@ impl<'a> ArchiveBuilder<'a> for ArArchiveBuilder<'a> {
         Ok(())
     }
 
-    fn build(mut self) {
+    fn build(mut self) -> bool {
         enum BuilderKind {
             Bsd(ar::Builder<File>),
             Gnu(ar::GnuBuilder<File>),
@@ -204,6 +173,8 @@ impl<'a> ArchiveBuilder<'a> for ArArchiveBuilder<'a> {
             )
         };
 
+        let any_members = !entries.is_empty();
+
         // Add all files
         for (entry_name, data) in entries.into_iter() {
             let header = ar::Header::new(entry_name, data.len() as u64);
@@ -229,6 +200,8 @@ impl<'a> ArchiveBuilder<'a> for ArArchiveBuilder<'a> {
                 self.sess.fatal(&format!("Ranlib exited with code {:?}", status.code()));
             }
         }
+
+        any_members
     }
 
     fn inject_dll_import_lib(