From 63317103c9f2b0635558da814567bb79c17ae851 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter@wuille.net>
Date: Mon, 16 Oct 2023 10:17:12 -0400
Subject: miniscript: make operator_mst consteval

It seems modern compilers don't realize that all invocations of operator""_mst
can be evaluated at compile time, despite the constexpr keyword.

Since C++20, we can force them to evaluate at compile time, turning all the
miniscript type constants into actual compile-time constants.

It appears that MSVC does not support consteval operator"" when used inside
certain expressions. For the few places where this happens, define a
constant outside the operator call.

Co-Authored-By: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>
---
 src/script/miniscript.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

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

diff --git a/src/script/miniscript.cpp b/src/script/miniscript.cpp
index 344a81bdf0..455bd56283 100644
--- a/src/script/miniscript.cpp
+++ b/src/script/miniscript.cpp
@@ -231,7 +231,8 @@ Type ComputeType(Fragment fragment, Type x, Type y, Type z, const std::vector<Ty
             Type acc_tl = "k"_mst;
             for (size_t i = 0; i < sub_types.size(); ++i) {
                 Type t = sub_types[i];
-                if (!(t << (i ? "Wdu"_mst : "Bdu"_mst))) return ""_mst; // Require Bdu, Wdu, Wdu, ...
+                static constexpr auto WDU{"Wdu"_mst}, BDU{"Bdu"_mst};
+                if (!(t << (i ? WDU : BDU))) return ""_mst; // Require Bdu, Wdu, Wdu, ...
                 if (!(t << "e"_mst)) all_e = false;
                 if (!(t << "m"_mst)) all_m = false;
                 if (t << "s"_mst) num_s += 1;
-- 
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