Review comments

Author: bjorn3

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -234,8 +234,6 @@ pub fn each_linked_rlib(
     crate_type: Option<CrateType>,
     f: &mut dyn FnMut(CrateNum, &Path),
 ) -> Result<(), errors::LinkRlibError> {
-    let crates = info.used_crates.iter();
-
     let fmts = if let Some(crate_type) = crate_type {
         let Some(fmts) = info.dependency_formats.get(&crate_type) else {
             return Err(errors::LinkRlibError::MissingFormat);
@@ -261,7 +259,8 @@ pub fn each_linked_rlib(
         info.dependency_formats.first().unwrap().1
     };
 
-    for &cnum in crates {
+    let used_dep_crates = info.used_crates.iter();
+    for &cnum in used_dep_crates {
         match fmts.get(cnum) {
             Some(&Linkage::NotLinked | &Linkage::Dynamic | &Linkage::IncludedFromDylib) => continue,
             Some(_) => {}

compiler/rustc_metadata/src/dependency_format.rs

@@ -212,7 +212,14 @@ fn calculate_type(tcx: TyCtxt<'_>, ty: CrateType) -> DependencyList {
     // Collect what we've got so far in the return vector.
     let last_crate = tcx.crates(()).len();
     let mut ret = IndexVec::new();
+
+    // We need to fill in something for LOCAL_CRATE as IndexVec is a dense map.
+    // Linkage::Static semantically the most correct thing to use as the local
+    // crate is always statically linked into the linker output, even when
+    // linking a dylib. Using Linkage::Static also allow avoiding special cases
+    // for LOCAL_CRATE in some places.
     assert_eq!(ret.push(Linkage::Static), LOCAL_CRATE);
+
     for cnum in 1..last_crate + 1 {
         let cnum = CrateNum::new(cnum);
         assert_eq!(