From c71de10608b23bc2d9137d5cd48ee956e2adbfa8 Mon Sep 17 00:00:00 2001
From: ringabout <43030857+ringabout@users.noreply.github.com>
Date: Tue, 5 Nov 2024 22:14:57 +0800
Subject: [PATCH] fixes strictdefs with `when nimvm` (#24409)

ref https://github.com/nim-lang/Nim/pull/24225
related https://github.com/nim-lang/Nim/pull/24306

> Code in branches must not affect semantics of the code that follows
the
`when nimvm` statement. E.g. it must not define symbols that are used in
  the following code.

The test shouldn't have passed when
https://github.com/nim-lang/Nim/pull/24306
would be implemented somehow. Some third packages have already misused
`when nimvm` by defining symbols in the other branch of `when nimvm`.

e.g. in https://github.com/status-im/nim-unittest2/pull/34

```nim
when nimvm:
  discard
else:
  let suiteName {.inject.} = nameParam

use(suiteName)
```
---
 compiler/sempass2.nim |  5 ++++-
 tests/init/tlet.nim   | 30 ++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/compiler/sempass2.nim b/compiler/sempass2.nim
index 76c3d5290b5df..a8dfb57854ce8 100644
--- a/compiler/sempass2.nim
+++ b/compiler/sempass2.nim
@@ -1301,7 +1301,10 @@ proc track(tracked: PEffects, n: PNode) =
       let last = lastSon(child)
       track(tracked, last)
   of nkCaseStmt: trackCase(tracked, n)
-  of nkWhen, nkIfStmt, nkIfExpr: trackIf(tracked, n)
+  of nkWhen: # This should be a "when nimvm" node.
+    track(tracked, n[0][1])
+    track(tracked, n[1][0])
+  of nkIfStmt, nkIfExpr: trackIf(tracked, n)
   of nkBlockStmt, nkBlockExpr: trackBlock(tracked, n[1])
   of nkWhileStmt:
     # 'while true' loop?
diff --git a/tests/init/tlet.nim b/tests/init/tlet.nim
index e32bedb1841ed..a3041baf876d2 100644
--- a/tests/init/tlet.nim
+++ b/tests/init/tlet.nim
@@ -1,3 +1,7 @@
+discard """
+  joinable: false
+"""
+
 {.experimental: "strictDefs".}
 
 proc bar(x: out string) =
@@ -53,3 +57,29 @@ proc foo() =
 
 static: foo()
 foo()
+
+proc foo2 =
+  when nimvm:
+    discard
+  else:
+    let x = 1
+  doAssert x == 1
+
+  when false:
+    discard
+  else:
+    let y = 2
+
+  doAssert y == 2
+
+  const e = 1
+  when e == 0:
+    discard
+  elif e == 1:
+    let z = 3
+  else:
+    discard
+
+  doAssert z == 3
+
+foo2()