From 4e1b5ee702139df93e8c343c59ef8bb7108d3023 Mon Sep 17 00:00:00 2001
From: ringabout <43030857+ringabout@users.noreply.github.com>
Date: Tue, 13 Feb 2024 15:10:28 +0800
Subject: [PATCH] fixes #18104; tranform one liner var decl before templates
 expansion (#23294)

fixes #18104

(cherry picked from commit 1e9a3c438bed693bc95d5b1a9501e1386163e1cc)
---
 compiler/semstmts.nim      | 18 ++++++++++++++++++
 tests/varstmt/tvardecl.nim |  7 +++++++
 2 files changed, 25 insertions(+)

diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index 1fde91888b..a071d83648 100644
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -780,6 +780,24 @@ proc makeVarTupleSection(c: PContext, n, a, def: PNode, typ: PType, symkind: TSy
 proc semVarOrLet(c: PContext, n: PNode, symkind: TSymKind): PNode =
   var b: PNode
   result = copyNode(n)
+
+  # transform var x, y = 12 into var x = 12; var y = 12
+  # bug #18104; transformation should be finished before templates expansion
+  # TODO: move warnings for tuple here
+  var transformed = copyNode(n)
+  for i in 0..<n.len:
+    var a = n[i]
+    if a.kind == nkIdentDefs and a.len > 3 and a[^1].kind != nkEmpty:
+      for j in 0..<a.len-2:
+        var b = newNodeI(nkIdentDefs, a.info)
+        b.add a[j]
+        b.add a[^2]
+        b.add copyTree(a[^1])
+        transformed.add b
+    else:
+      transformed.add a
+  let n = transformed
+
   for i in 0..<n.len:
     var a = n[i]
     if c.config.cmd == cmdIdeTools: suggestStmt(c, a)
diff --git a/tests/varstmt/tvardecl.nim b/tests/varstmt/tvardecl.nim
index 37bc4bad7a..d5ccfafb7e 100644
--- a/tests/varstmt/tvardecl.nim
+++ b/tests/varstmt/tvardecl.nim
@@ -2,6 +2,7 @@ discard """
   output: "44"
 """
 # Test the new variable declaration syntax
+import std/sequtils
 
 var
   x = 0
@@ -10,3 +11,9 @@ var
 
 write(stdout, a)
 writeLine(stdout, b) #OUT 44
+
+proc p() = # bug #18104
+  var x, y = newSeqWith(10, newString(3))
+  discard (x, y)
+
+p()