From e5aaa3d77af7459b37c0c4a37eb22c5fd0cda3e1 Mon Sep 17 00:00:00 2001
From: Antoine Poinsot <darosior@protonmail.com>
Date: Sun, 22 Jan 2023 12:49:44 +0100
Subject: miniscript: make 'd:' have the 'u' property under Tapscript context

In Tapscript MINIMALIF is a consensus rule, so we can rely on the fact
that the `DUP IF [X] ENDIF` will always put an exact 1 on the stack upon
satisfaction.
---
 src/script/miniscript.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

(limited to 'src/script/miniscript.cpp')

diff --git a/src/script/miniscript.cpp b/src/script/miniscript.cpp
index 82f65e5dde..15e0778ef5 100644
--- a/src/script/miniscript.cpp
+++ b/src/script/miniscript.cpp
@@ -33,7 +33,8 @@ Type SanitizeType(Type e) {
     return e;
 }
 
-Type ComputeType(Fragment fragment, Type x, Type y, Type z, const std::vector<Type>& sub_types, uint32_t k, size_t data_size, size_t n_subs, size_t n_keys) {
+Type ComputeType(Fragment fragment, Type x, Type y, Type z, const std::vector<Type>& sub_types, uint32_t k,
+                 size_t data_size, size_t n_subs, size_t n_keys, MiniscriptContext ms_ctx) {
     // Sanity check on data
     if (fragment == Fragment::SHA256 || fragment == Fragment::HASH256) {
         assert(data_size == 32);
@@ -116,7 +117,8 @@ Type ComputeType(Fragment fragment, Type x, Type y, Type z, const std::vector<Ty
             "e"_mst.If(x << "f"_mst) | // e=f_x
             (x & "ghijk"_mst) | // g=g_x, h=h_x, i=i_x, j=j_x, k=k_x
             (x & "ms"_mst) | // m=m_x, s=s_x
-            // NOTE: 'd:' is not 'u' under P2WSH as MINIMALIF is only a policy rule there.
+            // NOTE: 'd:' is 'u' under Tapscript but not P2WSH as MINIMALIF is only a policy rule there.
+            "u"_mst.If(IsTapscript(ms_ctx)) |
             "ndx"_mst; // n, d, x
         case Fragment::WRAP_V: return
             "V"_mst.If(x << "B"_mst) | // V=B_x
-- 
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