From 2e9e7f13ee7dda0ecf4010c6edc77d9e495c1633 Mon Sep 17 00:00:00 2001
From: ringabout <43030857+ringabout@users.noreply.github.com>
Date: Wed, 4 Dec 2024 22:12:30 +0800
Subject: [PATCH] don't track `result` initialization if it is marked `noinit`
 (#24499)

We don't track `noinit` for variables introduced in
https://github.com/nim-lang/Nim/pull/10566. It should be applied to
`result` if the function is marked `noinit`
---
 compiler/sempass2.nim | 6 +++++-
 lib/pure/volatile.nim | 1 -
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/compiler/sempass2.nim b/compiler/sempass2.nim
index f1e31b7f7e42..6b757b5f8552 100644
--- a/compiler/sempass2.nim
+++ b/compiler/sempass2.nim
@@ -1644,6 +1644,9 @@ proc trackProc*(c: PContext; s: PSym, body: PNode) =
      s.kind in {skProc, skFunc, skConverter, skMethod}:
     var res = s.ast[resultPos].sym # get result symbol
     t.scopes[res.id] = t.currentBlock
+    if sfNoInit in s.flags:
+      # marks result "noinit"
+      incl res.flags, sfNoInit
 
   track(t, body)
 
@@ -1662,7 +1665,8 @@ proc trackProc*(c: PContext; s: PSym, body: PNode) =
   if not isEmptyType(s.typ.returnType) and
      (s.typ.returnType.requiresInit or s.typ.returnType.skipTypes(abstractInst).kind == tyVar or
        noStrictDefs notin c.config.legacyFeatures) and
-     s.kind in {skProc, skFunc, skConverter, skMethod} and s.magic == mNone:
+     s.kind in {skProc, skFunc, skConverter, skMethod} and s.magic == mNone and
+     sfNoInit notin s.flags:
     var res = s.ast[resultPos].sym # get result symbol
     if res.id notin t.init and breaksBlock(body) != bsNoReturn:
       if tfRequiresInit in s.typ.returnType.flags:
diff --git a/lib/pure/volatile.nim b/lib/pure/volatile.nim
index 0b79b6101554..a38247c7db1d 100644
--- a/lib/pure/volatile.nim
+++ b/lib/pure/volatile.nim
@@ -19,7 +19,6 @@ proc volatileLoad*[T](src: ptr T): T {.inline, noinit.} =
     when defined(js):
       result = src[]
     else:
-      result = default(T)
       {.emit: [result, " = (*(", typeof(src[]), " volatile*)", src, ");"].}
 
 proc volatileStore*[T](dest: ptr T, val: T) {.inline.} =