From 548cde4701510ea66f14de338046034550700d70 Mon Sep 17 00:00:00 2001
From: Jim Blandy <jimb@red-bean.com>
Date: Mon, 21 Jun 2021 10:55:49 -0700
Subject: [PATCH] Clear Validator::valid_expression_list before validating each
 function.

If validation fails, `Validator` may be left with entries in
`valid_expression_list` and `valid_expression_set`. The validator does clear the
set before examining a function's body, but not the list, which means a
long-lived `Validator` could accumulate an unbounded amount of garbage in the
list.

(Minor cleanup: use structural update syntax where appropriate.)
---
 src/valid/function.rs | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/src/valid/function.rs b/src/valid/function.rs
index 0c68d8e04d..caac37e485 100644
--- a/src/valid/function.rs
+++ b/src/valid/function.rs
@@ -147,16 +147,7 @@ impl<'a> BlockContext<'a> {
     }
 
     fn with_flags(&self, flags: Flags) -> Self {
-        BlockContext {
-            flags,
-            info: self.info,
-            expressions: self.expressions,
-            types: self.types,
-            global_vars: self.global_vars,
-            functions: self.functions,
-            prev_infos: self.prev_infos,
-            return_type: self.return_type,
-        }
+        BlockContext { flags, ..*self }
     }
 
     fn get_expression(
@@ -576,6 +567,7 @@ impl super::Validator {
         }
 
         self.valid_expression_set.clear();
+        self.valid_expression_list.clear();
         for (handle, expr) in fun.expressions.iter() {
             if expr.needs_pre_emit() {
                 self.valid_expression_set.insert(handle.index());