From 5ec81d076b2ddd11655ec1e90938ea08c907ab0b Mon Sep 17 00:00:00 2001
From: ringabout <43030857+ringabout@users.noreply.github.com>
Date: Wed, 9 Aug 2023 19:49:30 +0800
Subject: [PATCH] fixes cascades of out parameters, which produces wrong
 ProveInit warnings (#22413)

---
 compiler/sempass2.nim     | 14 ++++++++++----
 tests/init/toutparams.nim | 14 ++++++++++++++
 2 files changed, 24 insertions(+), 4 deletions(-)
 create mode 100644 tests/init/toutparams.nim

diff --git a/compiler/sempass2.nim b/compiler/sempass2.nim
index af283af303..c12cc6cb3d 100644
--- a/compiler/sempass2.nim
+++ b/compiler/sempass2.nim
@@ -846,7 +846,9 @@ proc trackCall(tracked: PEffects; n: PNode) =
   if n.typ != nil:
     if tracked.owner.kind != skMacro and n.typ.skipTypes(abstractVar).kind != tyOpenArray:
       createTypeBoundOps(tracked, n.typ, n.info)
-  if getConstExpr(tracked.ownerModule, n, tracked.c.idgen, tracked.graph) == nil:
+
+  let notConstExpr = getConstExpr(tracked.ownerModule, n, tracked.c.idgen, tracked.graph) == nil
+  if notConstExpr:
     if a.kind == nkCast and a[1].typ.kind == tyProc:
       a = a[1]
     # XXX: in rare situations, templates and macros will reach here after
@@ -905,9 +907,6 @@ proc trackCall(tracked: PEffects; n: PNode) =
         optStaticBoundsCheck in tracked.currOptions:
       checkBounds(tracked, n[1], n[2])
 
-    if a.kind != nkSym or a.sym.magic notin {mRunnableExamples, mNBindSym, mExpandToAst, mQuoteAst}:
-      for i in 0..<n.safeLen:
-        track(tracked, n[i])
 
   if a.kind == nkSym and a.sym.name.s.len > 0 and a.sym.name.s[0] == '=' and
         tracked.owner.kind != skMacro:
@@ -943,6 +942,13 @@ proc trackCall(tracked: PEffects; n: PNode) =
           tracked.hasSideEffect = true
       else: discard
 
+  if notConstExpr and (a.kind != nkSym or
+      a.sym.magic notin {mRunnableExamples, mNBindSym, mExpandToAst, mQuoteAst}
+  ):
+    # tracked after out analysis
+    for i in 0..<n.safeLen:
+      track(tracked, n[i])
+
 type
   PragmaBlockContext = object
     oldLocked: int
diff --git a/tests/init/toutparams.nim b/tests/init/toutparams.nim
new file mode 100644
index 0000000000..5907685998
--- /dev/null
+++ b/tests/init/toutparams.nim
@@ -0,0 +1,14 @@
+discard """
+  matrix: "--warningAsError:ProveInit"
+"""
+
+{.experimental: "strictdefs".}
+
+proc foo(x: out int) =
+  x = 1
+
+proc bar(x: out int) =
+  foo(x)
+
+var s: int
+bar(s)