From 9486efc0220302fb63e7aba9df943531eaa4dac6 Mon Sep 17 00:00:00 2001
From: Martin Medler <36563496+martis42@users.noreply.github.com>
Date: Sun, 20 Sep 2026 18:21:40 +0200
Subject: [PATCH] Fix aliasing _has_include with a custom macro

Fixes https://github.com/boostorg/wave/issues/260
---
 include/boost/wave/util/cpp_macromap.hpp |  8 +++---
 test/testwave/testfiles/t_2_033.cpp      | 32 ++++++++++++++++++++++++
 test/testwave/testfiles/test.cfg         |  1 +
 3 files changed, 37 insertions(+), 4 deletions(-)
 create mode 100644 test/testwave/testfiles/t_2_033.cpp

diff --git a/include/boost/wave/util/cpp_macromap.hpp b/include/boost/wave/util/cpp_macromap.hpp
index fad958a3..c7b93bc4 100644
--- a/include/boost/wave/util/cpp_macromap.hpp
+++ b/include/boost/wave/util/cpp_macromap.hpp
@@ -224,7 +224,6 @@ class macromap {
     void rescan_replacement_list(token_type const &curr_token,
         macro_definition_type &macrodef, ContainerT &replacement_list,
         ContainerT &expanded, bool expand_operator_defined,
-        bool expand_operator_has_include,
         IteratorT &nfirst, IteratorT const &nlast);
 
     //  Resolves the operator defined() and replaces the token with "0" or "1"
@@ -1363,7 +1362,6 @@ macromap<ContextT>::rescan_replacement_list(token_type const &curr_token,
     macro_definition_type &macro_def, ContainerT &replacement_list,
     ContainerT &expanded,
     bool expand_operator_defined,
-    bool expand_operator_has_include,
     IteratorT &nfirst, IteratorT const &nlast)
 {
     if (!replacement_list.empty()) {
@@ -1394,9 +1392,11 @@ macromap<ContextT>::rescan_replacement_list(token_type const &curr_token,
         typename ContainerT::iterator begin_it = replacement_list.begin();
         typename ContainerT::iterator end_it = replacement_list.end();
 
+        // The replacement list does not contain tokens following the macro invocation.
+        // Defer __has_include resolution until the expanded tokens are rescanned with those tokens available.
         expand_whole_tokensequence(
             expanded, begin_it, end_it,
-            expand_operator_defined, expand_operator_has_include);
+            expand_operator_defined, false);
 
         // trim replacement list, leave placeholder tokens untouched
         impl::trim_replacement_list(expanded);
@@ -1643,7 +1643,7 @@ macromap<ContextT>::expand_macro(ContainerT &expanded,
     rescan_replacement_list(
         curr_token, macro_def, replacement_list,
         expanded_list, expand_operator_defined,
-        expand_operator_has_include, first, last);
+        first, last);
 
     ctx.get_hooks().rescanned_macro(ctx.derived(), expanded_list);
 
diff --git a/test/testwave/testfiles/t_2_033.cpp b/test/testwave/testfiles/t_2_033.cpp
new file mode 100644
index 00000000..9bab81eb
--- /dev/null
+++ b/test/testwave/testfiles/t_2_033.cpp
@@ -0,0 +1,32 @@
+/*=============================================================================
+    Boost.Wave: A Standard compliant C++ preprocessor library
+    http://www.boost.org/
+
+    Copyright (c) 2026 Martin Medler. Distributed under the Boost
+    Software License, Version 1.0. (See accompanying file
+    LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+=============================================================================*/
+
+//O --c++17
+//O -Werror
+//O -S.
+
+// An object-like macro alias for __has_include must be expanded once before
+// resolving the operator.
+#define HAS_INCLUDE __has_include
+#if HAS_INCLUDE(<t_2_033.cpp>)
+#define FOUND_SELF_VIA_ALIAS
+#else
+#warning has_include could not find this file through an alias
+#endif
+
+//H 10: t_2_033.cpp(16): #define
+//H 08: t_2_033.cpp(16): HAS_INCLUDE=__has_include
+//H 10: t_2_033.cpp(17): #if
+//H 01: t_2_033.cpp(16): HAS_INCLUDE
+//H 02: __has_include
+//H 03: __has_include
+//H 11: t_2_033.cpp(17): #if HAS_INCLUDE(<t_2_033.cpp>): 1
+//H 10: t_2_033.cpp(18): #define
+//H 08: t_2_033.cpp(18): FOUND_SELF_VIA_ALIAS=
+//H 10: t_2_033.cpp(19): #else
diff --git a/test/testwave/testfiles/test.cfg b/test/testwave/testfiles/test.cfg
index 10d51b91..872f04a5 100644
--- a/test/testwave/testfiles/test.cfg
+++ b/test/testwave/testfiles/test.cfg
@@ -85,6 +85,7 @@ t_2_029.cpp
 t_2_030.cpp
 t_2_031.cpp
 t_2_032.cpp
+t_2_033.cpp
 
 #
 # t_3: Predefined macros