From 6c7788adf373cd8f0dc5c4fe2b7674625631721e Mon Sep 17 00:00:00 2001
From: Russell O'Connor <roconnor@blockstream.io>
Date: Wed, 24 Dec 2025 09:50:30 -0500
Subject: [PATCH] Avoid Simplicity header dependency propogation

The problem with including <simplicity/elements/env.h> in interpreter.h is that
now everyone who needs to include interpreter.h also needs access to
Simplicity's header files too.

This commit breaks that dependency chain by using forward declarations.  It will
pay signifigant dividends when elements switches to CMake.
---
 src/script/interpreter.cpp |  5 +++++
 src/script/interpreter.h   | 12 +++++-------
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index d01d4a1a87..498343432e 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -13,6 +13,7 @@
 #include <script/script.h>
 #include <uint256.h>
 extern "C" {
+#include <simplicity/elements/env.h>
 #include <simplicity/elements/exec.h>
 #include <simplicity/errorCodes.h>
 }
@@ -2675,6 +2676,10 @@ void PrecomputedTransactionData::Init(const T& txTo, std::vector<CTxOut>&& spent
     }
 }
 
+void SimplicityTransactionDeleter::operator()(elementsTransaction* ptr) const {
+    simplicity_elements_freeTransaction(ptr);
+}
+
 template <class T>
 PrecomputedTransactionData::PrecomputedTransactionData(const T& txTo)
      : PrecomputedTransactionData(uint256{})
diff --git a/src/script/interpreter.h b/src/script/interpreter.h
index 6ec8339d9c..9bfab8650c 100644
--- a/src/script/interpreter.h
+++ b/src/script/interpreter.h
@@ -10,9 +10,6 @@
 #include <script/script_error.h>
 #include <span.h>
 #include <primitives/transaction.h>
-extern "C" {
-#include <simplicity/elements/env.h>
-}
 
 #include <optional>
 #include <vector>
@@ -169,12 +166,13 @@ enum : uint32_t {
 
 bool CheckSignatureEncoding(const std::vector<unsigned char> &vchSig, unsigned int flags, ScriptError* serror);
 
+// Forward declarations of Simplicity structures.
+struct elementsTransaction;
+struct rawElementsTapEnv;
+
 struct SimplicityTransactionDeleter
 {
-    void operator()(elementsTransaction* ptr)
-    {
-        simplicity_elements_freeTransaction(ptr);
-    }
+    void operator()(elementsTransaction* ptr) const;
 };
 using SimplicityTransactionUniquePtr = std::unique_ptr<elementsTransaction, SimplicityTransactionDeleter>;