Auto merge of #89282 - sexxi-goose:fix-88118, r=nikomatsakis

2229: Consume IfLet expr

When using the IfLet guard feature, we can ICE when attempting to resolve PlaceBuilders.
For pattern matching, we currently don't consume the IfLet expression when "visiting" the arms leading us to not "read" all variables and hence not being able to resolve them.

r? `@nikomatsakis`
Closes #88118

compiler/rustc_typeck/src/expr_use_visitor.rs

@@ -619,6 +619,8 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
 
         if let Some(hir::Guard::If(ref e)) = arm.guard {
             self.consume_expr(e)
+        } else if let Some(hir::Guard::IfLet(_, ref e)) = arm.guard {
+            self.consume_expr(e)
         }
 
         self.consume_expr(&arm.body);

src/test/ui/closures/2229_closure_analysis/issue-88118-2.rs

@@ -0,0 +1,24 @@
+// edition:2021
+// run-pass
+#![feature(if_let_guard)]
+#[allow(unused_must_use)]
+#[allow(dead_code)]
+
+fn print_error_count(registry: &Registry) {
+    |x: &Registry| {
+        match &x {
+            Registry if let _ = registry.try_find_description() => { }
+            //~^ WARNING: irrefutable `if let` guard pattern
+            _ => {}
+        }
+    };
+}
+
+struct Registry;
+impl Registry {
+    pub fn try_find_description(&self) {
+        unimplemented!()
+    }
+}
+
+fn main() {}

src/test/ui/closures/2229_closure_analysis/issue-88118-2.stderr

@@ -0,0 +1,12 @@
+warning: irrefutable `if let` guard pattern
+  --> $DIR/issue-88118-2.rs:10:29
+   |
+LL |             Registry if let _ = registry.try_find_description() => { }
+   |                             ^
+   |
+   = note: `#[warn(irrefutable_let_patterns)]` on by default
+   = note: this pattern will always match, so the guard is useless
+   = help: consider removing the guard and adding a `let` inside the match arm
+
+warning: 1 warning emitted
+