From 9f666494ebb2572e3a18ba5dd89bace629a8ef5a Mon Sep 17 00:00:00 2001
From: Mamy Ratsimbazafy <mamy_github@numforge.co>
Date: Tue, 9 Jun 2026 12:59:59 +0200
Subject: [PATCH] Fix #25883 tuple sighash collision

---
 compiler/sighashes.nim                         |  1 +
 .../t25883_tuple_sighash_collision.nim         | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)
 create mode 100644 tests/ccgbugs2/t25883_tuple_sighash_collision.nim

diff --git a/compiler/sighashes.nim b/compiler/sighashes.nim
index 3b688920e4..c4ee24b785 100644
--- a/compiler/sighashes.nim
+++ b/compiler/sighashes.nim
@@ -211,6 +211,7 @@ proc hashType(c: var MD5Context, t: PType; flags: set[ConsiderFlag]; conf: Confi
     c.hashTree(t.n, {}, conf)
   of tyTuple:
     c &= char(t.kind)
+    c &= t.len
     if t.n != nil and CoType notin flags:
       for i in 0..<t.n.len:
         assert(t.n[i].kind == nkSym)
diff --git a/tests/ccgbugs2/t25883_tuple_sighash_collision.nim b/tests/ccgbugs2/t25883_tuple_sighash_collision.nim
new file mode 100644
index 0000000000..5e4bf6fbc6
--- /dev/null
+++ b/tests/ccgbugs2/t25883_tuple_sighash_collision.nim
@@ -0,0 +1,18 @@
+discard """
+output: "5"
+"""
+
+# bug #25883: C codegen assigns same type hash to tuples with different nesting
+# but identical flattened content.
+# ((Int[1], Int[2]), Int[13], Int[14]) and ((Int[1], Int[2], Int[13]), Int[14])
+# must get distinct C type names.
+
+type
+  Int[V: static int] = object
+
+proc main() =
+  var b = ((1, 2), 13, 14)
+  var c = ((1, 2, 13), 14)
+  echo c[0][2]
+
+main()