From 535556875ef20d91addeb1b9a0d105bc77edc6d9 Mon Sep 17 00:00:00 2001
From: metagn <metagngn@gmail.com>
Date: Sun, 29 Sep 2024 11:23:59 +0300
Subject: [PATCH] fix logic for `dcEqIgnoreDistinct` in `sameType` (#24197)

fixes #22523

There were 2 problems with the code in `sameType` for
`dcEqIgnoreDistinct`:

1. The code that skipped `{tyDistinct, tyGenericInst}` only ran if the
given types had different kinds. This is fixed by always performing this
skip.
2. The code block below that checks if `tyGenericInst`s have different
values still ran for `dcEqIgnoreDistinct` since it checks if the given
types are generic insts, not the skipped types (and also only the 1st
given type). This is fixed by only invoking this block for `dcEq`;
`dcEqOrDistinctOf` (which is unused) also skips the first given type.
Arguably there is another issue here that `skipGenericAlias` only ever
skips 1 type.

These combined fix the issue (`T` is `GenericInst(V, 1, distinct int)`
and `D[0]` is `GenericInst(D, 0, distinct int)`).

(cherry picked from commit b0e6d28782ce8c3d8e0b4a64e01f21d6f900648f)
---
 compiler/types.nim                         | 23 +++++++++++-----------
 tests/distinct/tcomplexaddressableconv.nim | 21 ++++++++++++++++++++
 2 files changed, 33 insertions(+), 11 deletions(-)
 create mode 100644 tests/distinct/tcomplexaddressableconv.nim

diff --git a/compiler/types.nim b/compiler/types.nim
index 2c40329723..27ea70f3c9 100644
--- a/compiler/types.nim
+++ b/compiler/types.nim
@@ -1226,16 +1226,16 @@ proc sameTypeAux(x, y: PType, c: var TSameTypeClosure): bool =
     b = skipTypes(b[^1], {tyAlias})
   assert(a != nil)
   assert(b != nil)
-  if a.kind != b.kind:
-    case c.cmp
-    of dcEq: return false
-    of dcEqIgnoreDistinct:
-      a = a.skipTypes({tyDistinct, tyGenericInst})
-      b = b.skipTypes({tyDistinct, tyGenericInst})
-      if a.kind != b.kind: return false
-    of dcEqOrDistinctOf:
-      a = a.skipTypes({tyDistinct, tyGenericInst})
-      if a.kind != b.kind: return false
+  case c.cmp
+  of dcEq:
+    if a.kind != b.kind: return false
+  of dcEqIgnoreDistinct:
+    a = a.skipTypes({tyDistinct, tyGenericInst})
+    b = b.skipTypes({tyDistinct, tyGenericInst})
+    if a.kind != b.kind: return false
+  of dcEqOrDistinctOf:
+    a = a.skipTypes({tyDistinct, tyGenericInst})
+    if a.kind != b.kind: return false
 
   #[
     The following code should not run in the case either side is an generic alias,
@@ -1243,7 +1243,8 @@ proc sameTypeAux(x, y: PType, c: var TSameTypeClosure): bool =
     objects ie `type A[T] = SomeObject`
   ]#
   # this is required by tunique_type but makes no sense really:
-  if tyDistinct notin {x.kind, y.kind} and x.kind == tyGenericInst and IgnoreTupleFields notin c.flags:
+  if c.cmp == dcEq and x.kind == tyGenericInst and
+      IgnoreTupleFields notin c.flags and tyDistinct != y.kind:
     let
       lhs = x.skipGenericAlias
       rhs = y.skipGenericAlias
diff --git a/tests/distinct/tcomplexaddressableconv.nim b/tests/distinct/tcomplexaddressableconv.nim
new file mode 100644
index 0000000000..00e96bfeb7
--- /dev/null
+++ b/tests/distinct/tcomplexaddressableconv.nim
@@ -0,0 +1,21 @@
+# issue #22523
+
+from std/typetraits import distinctBase
+
+type
+  V[p: static int] = distinct int
+  D[p: static int] = distinct int
+  T = V[1]
+
+proc f(y: var T) = discard
+
+var a: D[0]
+
+static:
+  doAssert distinctBase(T) is distinctBase(D[0])
+  doAssert distinctBase(T) is int
+  doAssert distinctBase(D[0]) is int
+  doAssert T(a) is T
+
+f(cast[ptr T](addr a)[])
+f(T(a))