From c32d594d64c83780bd6b4a70bb5c19013ff8536a Mon Sep 17 00:00:00 2001
From: Zach Laine <whatwasthataddress@gmail.com>
Date: Sun, 12 Oct 2025 20:00:05 -0500
Subject: [PATCH] Eliminate double-instantiation of context templates (due to
 on a difference between a nope and nope const GlobalState template arg) by
 using nope const by default.

Fixes #250.
---
 include/boost/parser/concepts.hpp   | 2 +-
 include/boost/parser/parser.hpp     | 8 ++++----
 include/boost/parser/parser_fwd.hpp | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/boost/parser/concepts.hpp b/include/boost/parser/concepts.hpp
index 5f7295c0..296ca92f 100644
--- a/include/boost/parser/concepts.hpp
+++ b/include/boost/parser/concepts.hpp
@@ -59,7 +59,7 @@ namespace boost { namespace parser {
         std::declval<bool &>(),
         std::declval<int &>(),
         std::declval<ErrorHandler const &>(),
-        std::declval<detail::nope &>(),
+        std::declval<detail::nope const &>(),
         std::declval<detail::symbol_table_tries_t &>(),
         std::declval<detail::pending_symbol_table_operations_t &>()));
 
diff --git a/include/boost/parser/parser.hpp b/include/boost/parser/parser.hpp
index c701ca49..31caa8cd 100644
--- a/include/boost/parser/parser.hpp
+++ b/include/boost/parser/parser.hpp
@@ -412,7 +412,7 @@ namespace boost { namespace parser {
             }
         };
 
-        inline nope global_nope;
+        inline nope const global_nope;
 
         template<typename T>
         using parser_interface_tag_expr =
@@ -433,7 +433,7 @@ namespace boost { namespace parser {
             typename I,
             typename S,
             typename ErrorHandler,
-            typename GlobalState = nope,
+            typename GlobalState = nope const,
             typename Callbacks = nope,
             typename Attr = nope,
             typename Val = nope,
@@ -747,7 +747,7 @@ namespace boost { namespace parser {
             bool & success,
             int & indent,
             ErrorHandler const & error_handler,
-            nope & n,
+            nope const & n,
             symbol_table_tries_t & symbol_table_tries,
             pending_symbol_table_operations_t &
                 pending_symbol_table_operations) noexcept
@@ -1518,7 +1518,7 @@ namespace boost { namespace parser {
             bool success = true;
             int indent = 0;
             rethrow_error_handler eh;
-            nope n;
+            nope const n;
             symbol_table_tries_t symbol_table_tries;
             pending_symbol_table_operations_t pending_symbol_table_operations;
             auto const context = detail::make_context<false, false>(
diff --git a/include/boost/parser/parser_fwd.hpp b/include/boost/parser/parser_fwd.hpp
index 43c7eebb..44565e88 100644
--- a/include/boost/parser/parser_fwd.hpp
+++ b/include/boost/parser/parser_fwd.hpp
@@ -115,7 +115,7 @@ namespace boost { namespace parser {
             bool & success,
             int & indent,
             ErrorHandler const & error_handler,
-            nope &,
+            nope const &,
             symbol_table_tries_t & symbol_table_tries,
             pending_symbol_table_operations_t &
                 pending_symbol_table_operations) noexcept;