From 049db89039a5c9ed0818ad82613b55015478bbf0 Mon Sep 17 00:00:00 2001
From: Jim Blandy <jimb@red-bean.com>
Date: Fri, 31 May 2024 16:14:16 -0700
Subject: [PATCH] [naga] Remove `ExpressionError::DoesntExist`.

Remove `valid::expression::ExpressionError::DoesntExist`. This error is reported
when expression validation encounters an invalid `Handle<Expression>`, but we
have already verified that the module is free of invalid handles in
`Validator::validate_module_handles`, so this condition should never arise.
---
 naga/src/valid/expression.rs |  2 --
 naga/src/valid/function.rs   | 13 ++-----------
 2 files changed, 2 insertions(+), 13 deletions(-)

diff --git a/naga/src/valid/expression.rs b/naga/src/valid/expression.rs
index adcf4b888..c6e225990 100644
--- a/naga/src/valid/expression.rs
+++ b/naga/src/valid/expression.rs
@@ -12,8 +12,6 @@ use crate::{
 #[derive(Clone, Debug, thiserror::Error)]
 #[cfg_attr(test, derive(PartialEq))]
 pub enum ExpressionError {
-    #[error("Doesn't exist")]
-    DoesntExist,
     #[error("Used by a statement before it was introduced into the scope by any of the dominating blocks")]
     NotInScope,
     #[error("Base type {0:?} is not compatible with this expression")]
diff --git a/naga/src/valid/function.rs b/naga/src/valid/function.rs
index 543f71fed..f05ac3041 100644
--- a/naga/src/valid/function.rs
+++ b/naga/src/valid/function.rs
@@ -241,9 +241,7 @@ impl<'a> BlockContext<'a> {
         handle: Handle<crate::Expression>,
         valid_expressions: &BitSet,
     ) -> Result<&crate::TypeInner, WithSpan<ExpressionError>> {
-        if handle.index() >= self.expressions.len() {
-            Err(ExpressionError::DoesntExist.with_span())
-        } else if !valid_expressions.contains(handle.index()) {
+        if !valid_expressions.contains(handle.index()) {
             Err(ExpressionError::NotInScope.with_span_handle(handle, self.expressions))
         } else {
             Ok(self.info[handle].ty.inner_with(self.types))
@@ -263,14 +261,7 @@ impl<'a> BlockContext<'a> {
         &self,
         handle: Handle<crate::Expression>,
     ) -> Result<&crate::TypeInner, FunctionError> {
-        if handle.index() >= self.expressions.len() {
-            Err(FunctionError::Expression {
-                handle,
-                source: ExpressionError::DoesntExist,
-            })
-        } else {
-            Ok(self.info[handle].ty.inner_with(self.types))
-        }
+        Ok(self.info[handle].ty.inner_with(self.types))
     }
 }