From: Roxane Date: Fri, 27 Aug 2021 13:00:50 +0000 (-0400) Subject: Add comment and fix fmt issue X-Git-Url: https://git.lizzy.rs/?a=commitdiff_plain;h=110a9b3b1ca1fddd34a3ecb8ec47fd8bb5ca7424;p=rust.git Add comment and fix fmt issue --- diff --git a/compiler/rustc_typeck/src/expr_use_visitor.rs b/compiler/rustc_typeck/src/expr_use_visitor.rs index e7c3a366cc4..7c99a37f6e7 100644 --- a/compiler/rustc_typeck/src/expr_use_visitor.rs +++ b/compiler/rustc_typeck/src/expr_use_visitor.rs @@ -268,10 +268,21 @@ pub fn walk_expr(&mut self, expr: &hir::Expr<'_>) { if def.variants.len() > 1 { needs_to_be_read = true; } else if let Some(variant) = def.variants.iter().next() { + // We need to handle `const` in match arms slightly differently + // as they are not processed the same way as other match arms. + // Consider this const `const OP1: Opcode = Opcode(0x1)`, this + // will generate a pattern with kind Path while if use Opcode(0x1) + // this will generate pattern TupleStruct and Lit. + // When dealing with pat kind Path we need to make additional checks + // to ensure we have all the info needed to make a decision on whether + // to borrow discr. + // // If the pat kind is a Path we want to check whether the // variant contains at least one field. If that's the case, // we want to borrow discr. - if matches!(pat.kind, PatKind::Path(..)) && variant.fields.len() > 0 { + if matches!(pat.kind, PatKind::Path(..)) + && variant.fields.len() > 0 + { needs_to_be_read = true; } }