Auto merge of #53815 - F001:if-let-guard, r=petrochenkov

refactor match guard

This is the first step to implement RFC 2294: if-let-guard. Tracking issue: https://github.com/rust-lang/rust/issues/51114

The second step should be introducing another variant `IfLet` in the Guard enum. I separated them into 2 PRs for the convenience of reviewers.

r? @petrochenkov

1 files changed, 8 insertions, 4 deletions

diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index e78e1afe3a4..85d29a5be89 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -2702,10 +2702,14 @@ impl<'a> State<'a> {
         self.print_outer_attributes(&arm.attrs)?;
         self.print_pats(&arm.pats)?;
         self.s.space()?;
-        if let Some(ref e) = arm.guard {
-            self.word_space("if")?;
-            self.print_expr(e)?;
-            self.s.space()?;
+        if let Some(ref g) = arm.guard {
+            match g {
+                ast::Guard::If(ref e) => {
+                    self.word_space("if")?;
+                    self.print_expr(e)?;
+                    self.s.space()?;
+                }
+            }
         }
         self.word_space("=>")?;