From 2abb4c99fe8a5839fe2910e90f3471e6308f6229 Mon Sep 17 00:00:00 2001
From: Dawer <7803845+iDawer@users.noreply.github.com>
Date: Sat, 15 May 2021 00:09:17 +0500
Subject: Fix false positive "Missing match arm".

---
 crates/hir_ty/src/diagnostics/match_check.rs | 1 +
 crates/hir_ty/src/infer/pat.rs               | 9 +++++----
 crates/hir_ty/src/tests/patterns.rs          | 2 +-
 3 files changed, 7 insertions(+), 5 deletions(-)

(limited to 'crates/hir_ty')

diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs
index e9762622f..6ee0529c6 100644
--- a/crates/hir_ty/src/diagnostics/match_check.rs
+++ b/crates/hir_ty/src/diagnostics/match_check.rs
@@ -1119,6 +1119,7 @@ fn main() {
         (true, false, true) => (),
         (true) => (),
     }
+    match (true, false) { (true,) => {} }
     match (0) { () => () }
     match Unresolved::Bar { Unresolved::Baz => () }
 }
diff --git a/crates/hir_ty/src/infer/pat.rs b/crates/hir_ty/src/infer/pat.rs
index aea354cde..60b94a642 100644
--- a/crates/hir_ty/src/infer/pat.rs
+++ b/crates/hir_ty/src/infer/pat.rs
@@ -126,11 +126,12 @@ impl<'a> InferenceContext<'a> {
                     _ => &[],
                 };
 
-                let (pre, post) = match ellipsis {
-                    Some(idx) => args.split_at(idx),
-                    None => (&args[..], &[][..]),
+                let ((pre, post), n_uncovered_patterns) = match ellipsis {
+                    Some(idx) => {
+                        (args.split_at(idx), expectations.len().saturating_sub(args.len()))
+                    }
+                    None => ((&args[..], &[][..]), 0),
                 };
-                let n_uncovered_patterns = expectations.len().saturating_sub(args.len());
                 let err_ty = self.err_ty();
                 let mut expectations_iter =
                     expectations.iter().map(|a| a.assert_ty_ref(&Interner)).chain(repeat(&err_ty));
diff --git a/crates/hir_ty/src/tests/patterns.rs b/crates/hir_ty/src/tests/patterns.rs
index 33305f208..a0a7b4d0b 100644
--- a/crates/hir_ty/src/tests/patterns.rs
+++ b/crates/hir_ty/src/tests/patterns.rs
@@ -732,7 +732,7 @@ fn foo(tuple: (u8, i16, f32)) {
             111..112 'a': u8
             114..115 'b': i16
             124..126 '{}': ()
-            136..142 '(a, b)': (u8, i16, f32)
+            136..142 '(a, b)': (u8, i16)
             137..138 'a': u8
             140..141 'b': i16
             146..161 '{/*too short*/}': ()
-- 
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