address comments

Author: mustartt

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -778,6 +778,10 @@ fn link_natively(
     let (linker_path, flavor) = linker_and_flavor(sess);
     let self_contained_components = self_contained_components(sess, crate_type);
 
+    // On AIX, we ship all libraries as .a big_af archive
+    // the expected format is lib<name>.a(libname.so) for the actual
+    // dynamic library. So we link to a temporary .so file to be archived
+    // at the final out_filename location
     let should_archive = crate_type != CrateType::Executable && sess.target.is_like_aix;
     let archive_member =
         should_archive.then(|| tmpdir.join(out_filename.file_name().unwrap()).with_extension("so"));

compiler/rustc_metadata/Cargo.toml

@@ -6,6 +6,7 @@ edition = "2021"
 [dependencies]
 # tidy-alphabetical-start
 bitflags = "2.4.1"
+libc = "0.2"
 libloading = "0.8.0"
 odht = { version = "0.3.1", features = ["nightly"] }
 rustc_abi = { path = "../rustc_abi" }

compiler/rustc_metadata/src/creader.rs

@@ -3,6 +3,7 @@
 use std::error::Error;
 use std::ops::Fn;
 use std::path::Path;
+use std::ffi::OsString;
 use std::str::FromStr;
 use std::time::Duration;
 use std::{cmp, env, iter};
@@ -1178,9 +1179,7 @@ fn attempt_load_dylib(path: &Path) -> Result<libloading::Library, libloading::Er
         let new_path = path.with_extension(archive_member);
 
         // On AIX, we need RTLD_MEMBER to dlopen an archived shared
-        // flags = RTLD_LAZY | RTLD_LOCAL | RTLD_MEMBER
-        // these are not yet in libc https://github.com/rust-lang/libc/pull/4044
-        let flags = 0x4 | 0x80000 | 0x40000;
+        let flags = libc::RTLD_LAZY | libc::RTLD_LOCAL | libc::RTLD_MEMBER;
         return unsafe { libloading::os::unix::Library::open(Some(&new_path), flags) }
             .map(|lib| lib.into());
     }

src/bootstrap/src/utils/helpers.rs

@@ -61,8 +61,8 @@ pub fn is_dylib(path: &Path) -> bool {
 }
 
 fn is_aix_shared_archive(path: &Path) -> bool {
-    // todo: reading the entire file as &[u8] into memory seems excessive
-    // look into either mmap it or use the &CacheReader
+    // FIXME(#133268): reading the entire file as &[u8] into memory seems excessive
+    // look into either mmap it or use the ReadCache 
     let data = match fs::read(path) {
         Ok(data) => data,
         Err(_) => return false,