From 7c5275939a316852cb07878f9d3076bff7e65b96 Mon Sep 17 00:00:00 2001
From: Lukas Wirth <lukastw97@gmail.com>
Date: Fri, 6 Sep 2024 14:44:05 +0200
Subject: [PATCH] fix: Properly prevent mir building with unknown types present

---
 crates/hir-ty/src/infer.rs                          | 13 +++++++++++--
 crates/hir-ty/src/mir.rs                            |  4 ++--
 .../src/handlers/mutability_errors.rs               |  2 +-
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/crates/hir-ty/src/infer.rs b/crates/hir-ty/src/infer.rs
index 0e68ab4bfe..8bc3c50725 100644
--- a/crates/hir-ty/src/infer.rs
+++ b/crates/hir-ty/src/infer.rs
@@ -708,7 +708,6 @@ impl<'a> InferenceContext<'a> {
             tuple_field_access_types: _,
             coercion_casts,
         } = &mut result;
-
         table.fallback_if_possible();
 
         // Comment from rustc:
@@ -754,7 +753,7 @@ impl<'a> InferenceContext<'a> {
             *has_errors = *has_errors || ty.contains_unknown();
         }
 
-        *has_errors = !type_mismatches.is_empty();
+        *has_errors |= !type_mismatches.is_empty();
 
         type_mismatches.retain(|_, mismatch| {
             mismatch.expected = table.resolve_completely(mismatch.expected.clone());
@@ -797,20 +796,30 @@ impl<'a> InferenceContext<'a> {
         });
         for (_, subst) in method_resolutions.values_mut() {
             *subst = table.resolve_completely(subst.clone());
+            *has_errors =
+                *has_errors || subst.type_parameters(Interner).any(|ty| ty.contains_unknown());
         }
         for (_, subst) in assoc_resolutions.values_mut() {
             *subst = table.resolve_completely(subst.clone());
+            *has_errors =
+                *has_errors || subst.type_parameters(Interner).any(|ty| ty.contains_unknown());
         }
         for adjustment in expr_adjustments.values_mut().flatten() {
             adjustment.target = table.resolve_completely(adjustment.target.clone());
+            *has_errors = *has_errors || adjustment.target.contains_unknown();
         }
         for adjustment in pat_adjustments.values_mut().flatten() {
             *adjustment = table.resolve_completely(adjustment.clone());
+            *has_errors = *has_errors || adjustment.contains_unknown();
         }
         result.tuple_field_access_types = tuple_field_accesses_rev
             .into_iter()
             .enumerate()
             .map(|(idx, subst)| (TupleId(idx as u32), table.resolve_completely(subst)))
+            .inspect(|(_, subst)| {
+                *has_errors =
+                    *has_errors || subst.type_parameters(Interner).any(|ty| ty.contains_unknown());
+            })
             .collect();
         result
     }
diff --git a/crates/hir-ty/src/mir.rs b/crates/hir-ty/src/mir.rs
index 8cd6ae1232..8e815aabf2 100644
--- a/crates/hir-ty/src/mir.rs
+++ b/crates/hir-ty/src/mir.rs
@@ -185,8 +185,8 @@ impl<V, T> ProjectionElem<V, T> {
                         never!("Out of bound tuple field");
                         TyKind::Error.intern(Interner)
                     }),
-                _ => {
-                    never!("Only tuple has tuple field");
+                ty => {
+                    never!("Only tuple has tuple field: {:?}", ty);
                     TyKind::Error.intern(Interner)
                 }
             },
diff --git a/crates/ide-diagnostics/src/handlers/mutability_errors.rs b/crates/ide-diagnostics/src/handlers/mutability_errors.rs
index e4b1f3ca95..9554279391 100644
--- a/crates/ide-diagnostics/src/handlers/mutability_errors.rs
+++ b/crates/ide-diagnostics/src/handlers/mutability_errors.rs
@@ -824,13 +824,13 @@ fn f() {
 
     #[test]
     fn or_pattern() {
+        // FIXME: `None` is inferred as unknown here for some reason
         check_diagnostics(
             r#"
 //- minicore: option
 fn f(_: i32) {}
 fn main() {
     let ((Some(mut x), None) | (_, Some(mut x))) = (None, Some(7)) else { return };
-             //^^^^^ 💡 warn: variable does not need to be mutable
     f(x);
 }
 "#,