BE: Bring in a type alias for Guards in HIR

Summary: As title

Reviewed By: robertoaloi

Differential Revision: D61590977

fbshipit-source-id: 8200c34f203da5e6af28da656e969e93822ab885

crates/hir/src/body/lower.rs

@@ -31,6 +31,7 @@ use super::InFileAstPtr;
 use super::TopLevelMacro;
 use crate::db::DefDatabase;
 use crate::def_map::FunctionDefId;
+use crate::expr::Guards;
 use crate::expr::MaybeExpr;
 use crate::expr::StringVariant;
 use crate::known;
@@ -1617,7 +1618,7 @@ impl<'a> Ctx<'a> {
         }
     }
 
-    fn lower_guards(&mut self, guards: Option<ast::Guard>) -> Vec<Vec<ExprId>> {
+    fn lower_guards(&mut self, guards: Option<ast::Guard>) -> Guards {
         guards
             .iter()
             .flat_map(|guard| guard.clauses())

crates/hir/src/body/pretty.rs

@@ -13,6 +13,7 @@ use std::str;
 
 use super::SpecOrCallback;
 use crate::db::InternDatabase;
+use crate::expr::Guards;
 use crate::expr::MaybeExpr;
 use crate::expr::StringVariant;
 use crate::AnyAttribute;
@@ -304,7 +305,7 @@ impl<'a> Printer<'a> {
         }
     }
 
-    fn print_guards(&mut self, guards: &[Vec<ExprId>], when_nested: bool) -> fmt::Result {
+    fn print_guards(&mut self, guards: &Guards, when_nested: bool) -> fmt::Result {
         if !guards.is_empty() {
             if when_nested {
                 self.indent_level += 1;

crates/hir/src/body/tree_print.rs

@@ -15,6 +15,7 @@ use std::fmt::Write as _;
 use std::str;
 
 use crate::db::InternDatabase;
+use crate::expr::Guards;
 use crate::expr::MaybeExpr;
 use crate::AnyAttribute;
 use crate::AttributeBody;
@@ -1015,7 +1016,7 @@ impl<'a> Printer<'a> {
         });
     }
 
-    fn print_guards(&mut self, guards: &[Vec<ExprId>]) {
+    fn print_guards(&mut self, guards: &Guards) {
         if !guards.is_empty() {
             for guard_clause in guards {
                 self.print_labelled("guard", false, &mut |this| {

crates/hir/src/expr.rs

@@ -379,23 +379,25 @@ impl AstClauseId {
     }
 }
 
+pub type Guards = Vec<Vec<ExprId>>;
+
 #[derive(Debug, Clone, Eq, PartialEq, Default)]
 pub struct Clause {
     pub pats: Vec<PatId>,
-    pub guards: Vec<Vec<ExprId>>,
+    pub guards: Guards,
     pub exprs: Vec<ExprId>,
 }
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct CRClause {
     pub pat: PatId,
-    pub guards: Vec<Vec<ExprId>>,
+    pub guards: Guards,
     pub exprs: Vec<ExprId>,
 }
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct IfClause {
-    pub guards: Vec<Vec<ExprId>>,
+    pub guards: Guards,
     pub exprs: Vec<ExprId>,
 }
 
@@ -404,7 +406,7 @@ pub struct CatchClause {
     pub class: Option<PatId>,
     pub reason: PatId,
     pub stack: Option<PatId>,
-    pub guards: Vec<Vec<ExprId>>,
+    pub guards: Guards,
     pub exprs: Vec<ExprId>,
 }