refactor if-let lowering

mainly to get rid of unwraps

1 files changed, 25 insertions, 19 deletions

diff --git a/crates/ra_hir/src/expr.rs b/crates/ra_hir/src/expr.rs
index 9fea70dda..b59787a83 100644
--- a/crates/ra_hir/src/expr.rs
+++ b/crates/ra_hir/src/expr.rs
@@ -559,6 +559,7 @@ where
         match expr.kind() {
             ast::ExprKind::IfExpr(e) => {
                 let then_branch = self.collect_block_opt(e.then_branch());
+
                 let else_branch = e.else_branch().map(|b| match b {
                     ast::ElseBranch::Block(it) => self.collect_block(it),
                     ast::ElseBranch::IfExpr(elif) => {
@@ -567,25 +568,30 @@ where
                     }
                 });
 
-                if let Some(pat) = e.condition().and_then(|c| c.pat()) {
-                    // if let -- desugar to match
-                    let pat = self.collect_pat(pat);
-                    let match_expr =
-                        self.collect_expr_opt(e.condition().expect("checked above").expr());
-                    let placeholder_pat = self.pats.alloc(Pat::Missing);
-                    let arms = vec![
-                        MatchArm { pats: vec![pat], expr: then_branch, guard: None },
-                        MatchArm {
-                            pats: vec![placeholder_pat],
-                            expr: else_branch.unwrap_or_else(|| self.empty_block()),
-                            guard: None,
-                        },
-                    ];
-                    self.alloc_expr(Expr::Match { expr: match_expr, arms }, syntax_ptr)
-                } else {
-                    let condition = self.collect_expr_opt(e.condition().and_then(|c| c.expr()));
-                    self.alloc_expr(Expr::If { condition, then_branch, else_branch }, syntax_ptr)
-                }
+                let condition = match e.condition() {
+                    None => self.exprs.alloc(Expr::Missing),
+                    Some(condition) => match condition.pat() {
+                        None => self.collect_expr_opt(condition.expr()),
+                        // if let -- desugar to match
+                        Some(pat) => {
+                            let pat = self.collect_pat(pat);
+                            let match_expr = self.collect_expr_opt(condition.expr());
+                            let placeholder_pat = self.pats.alloc(Pat::Missing);
+                            let arms = vec![
+                                MatchArm { pats: vec![pat], expr: then_branch, guard: None },
+                                MatchArm {
+                                    pats: vec![placeholder_pat],
+                                    expr: else_branch.unwrap_or_else(|| self.empty_block()),
+                                    guard: None,
+                                },
+                            ];
+                            return self
+                                .alloc_expr(Expr::Match { expr: match_expr, arms }, syntax_ptr);
+                        }
+                    },
+                };
+
+                self.alloc_expr(Expr::If { condition, then_branch, else_branch }, syntax_ptr)
             }
             ast::ExprKind::TryBlockExpr(e) => {
                 let body = self.collect_block_opt(e.try_body());