diff options
Diffstat (limited to 'compiler/rustc_middle/src/mir/syntax.rs')
| -rw-r--r-- | compiler/rustc_middle/src/mir/syntax.rs | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs index fea7819d545..0b95fdfa1fb 100644 --- a/compiler/rustc_middle/src/mir/syntax.rs +++ b/compiler/rustc_middle/src/mir/syntax.rs @@ -1077,9 +1077,12 @@ pub enum ProjectionElem<V, T> { OpaqueCast(T), /// A `Subtype(T)` projection is applied to any `StatementKind::Assign` where - /// type of lvalue doesn't match type of rvalue, primary goal being making subtyping + /// type of lvalue doesn't match the type of rvalue, the primary goal is making subtyping /// explicit during optimizations and codegen. /// + /// This projection doesn't impact the runtime behavior of the program except for potentially changing + /// some type metadata of the interpreter or codegen backend. + /// /// This goal is achieved with mir_transform pass `Subtyper`, which runs right after /// borrowchecker, as we only care about subtyping that can affect trait selection and /// `TypeId`. |