Check tuple elements are Sized in offset_of

Author: clubby789

compiler/rustc_hir_typeck/src/expr.rs

@@ -3117,16 +3117,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     }
                 }
                 ty::Tuple(tys) => {
-                    let fstr = field.as_str();
-
-                    if let Ok(index) = fstr.parse::<usize>() {
-                        if fstr == index.to_string() {
-                            if let Some(&field_ty) = tys.get(index) {
-                                field_indices.push(index.into());
-                                current_container = field_ty;
+                    if let Ok(index) = field.as_str().parse::<usize>()
+                        && field.name == sym::integer(index)
+                    {
+                        for ty in tys.iter().take(index + 1) {
+                            self.require_type_is_sized(ty, expr.span, traits::MiscObligation);
+                        }
+                        if let Some(&field_ty) = tys.get(index) {
+                            field_indices.push(index.into());
+                            current_container = field_ty;
 
-                                continue;
-                            }
+                            continue;
                         }
                     }
                 }

tests/ui/offset-of/offset-of-dst-field.rs

@@ -36,6 +36,8 @@ fn main() {
     offset_of!(Alpha, z); //~ ERROR the size for values of type
     offset_of!(Beta, z); //~ ERROR the size for values of type
     offset_of!(Gamma, z); //~ ERROR the size for values of type
+    offset_of!((u8, dyn Trait), 0); // ok
+    offset_of!((u8, dyn Trait), 1); //~ ERROR the size for values of type
 }
 
 fn delta() {

tests/ui/offset-of/offset-of-dst-field.stderr

@@ -25,8 +25,17 @@ LL |     offset_of!(Gamma, z);
    = help: the trait `Sized` is not implemented for `Extern`
    = note: this error originates in the macro `offset_of` (in Nightly builds, run with -Z macro-backtrace for more info)
 
+error[E0277]: the size for values of type `dyn Trait` cannot be known at compilation time
+  --> $DIR/offset-of-dst-field.rs:40:5
+   |
+LL |     offset_of!((u8, dyn Trait), 1);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `dyn Trait`
+   = note: this error originates in the macro `offset_of` (in Nightly builds, run with -Z macro-backtrace for more info)
+
 error[E0277]: the size for values of type `Extern` cannot be known at compilation time
-  --> $DIR/offset-of-dst-field.rs:43:5
+  --> $DIR/offset-of-dst-field.rs:45:5
    |
 LL |     offset_of!(Delta<Extern>, z);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
@@ -35,7 +44,7 @@ LL |     offset_of!(Delta<Extern>, z);
    = note: this error originates in the macro `offset_of` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0277]: the size for values of type `dyn Trait` cannot be known at compilation time
-  --> $DIR/offset-of-dst-field.rs:44:5
+  --> $DIR/offset-of-dst-field.rs:46:5
    |
 LL |     offset_of!(Delta<dyn Trait>, z);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
@@ -44,7 +53,7 @@ LL |     offset_of!(Delta<dyn Trait>, z);
    = note: this error originates in the macro `offset_of` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0277]: the size for values of type `[u8]` cannot be known at compilation time
-  --> $DIR/offset-of-dst-field.rs:42:5
+  --> $DIR/offset-of-dst-field.rs:44:5
    |
 LL |     offset_of!(Delta<Alpha>, z);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
@@ -58,7 +67,7 @@ LL | struct Alpha {
    = note: this error originates in the macro `offset_of` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0277]: the size for values of type `T` cannot be known at compilation time
-  --> $DIR/offset-of-dst-field.rs:48:5
+  --> $DIR/offset-of-dst-field.rs:50:5
    |
 LL | fn generic_with_maybe_sized<T: ?Sized>() -> usize {
    |                             - this type parameter needs to be `std::marker::Sized`
@@ -72,6 +81,6 @@ LL - fn generic_with_maybe_sized<T: ?Sized>() -> usize {
 LL + fn generic_with_maybe_sized<T>() -> usize {
    |
 
-error: aborting due to 7 previous errors
+error: aborting due to 8 previous errors
 
 For more information about this error, try `rustc --explain E0277`.

tests/ui/offset-of/offset-of-unsized.rs

@@ -1,5 +1,6 @@
 // build-pass
-// regression test for #112051
+// regression test for #112051, not in `offset-of-dst` as the issue is in codegen,
+// and isn't triggered in the presence of typeck errors
 
 #![feature(offset_of)]