Address review comments

Co-authored-by: Ralf Jung <post@ralfj.de>

Author: Jules-Bertholet

compiler/rustc_abi/src/layout.rs

@@ -500,6 +500,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
             return Err(LayoutCalculatorError::EmptyUnion);
         };
 
+        // We also need to check for a `repr(transparent)` wrapper around `repr(C)`
         let repr_c =
             repr.c() || (repr.transparent() && only_variant.iter().any(|field| field.repr_c));
 
@@ -1489,6 +1490,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
             unadjusted_abi_align
         };
 
+        // We also need to check for a `repr(transparent)` wrapper around `repr(C)`
         let repr_c = repr.c() || (repr.transparent() && fields.iter().any(|field| field.repr_c));
 
         let seed = field_seed.wrapping_add(repr.field_shuffle_seed);

compiler/rustc_target/src/callconv/x86_win64.rs

@@ -49,7 +49,7 @@ where
     };
 
     // Windows ABIs do not talk about ZST since such types do not exist in MSVC.
-    // However, clang and gcc allow ZST is their windows-gnu targets, and pass them by pointer indierction.
+    // However, clang and gcc allow ZST in their windows-gnu targets, and pass them by pointer indirection.
     // We follow that for `repr(C)` ZSTs (and `repr(transparent)` wrappers around them),
     // but `repr(Rust)` ones are always ignored (ensuring that `()` matches C `void`).
 

tests/codegen-llvm/abi-win64-zst.rs

@@ -138,7 +138,7 @@ extern "sysv64" fn ret_c_maybezst_sysv64() -> CMaybeZst {
     CMaybeZst
 }
 
-// For `extern "C"` functions, ZST are ignored on Linux put reted on Windows.
+// For `extern "C"` functions, ZST are ignored on Linux but returned via pointer on Windows.
 
 // linux: define void @ret_c_maybezst_c()
 // windows-msvc: define void @ret_c_maybezst_c(ptr {{[^,]*}})