From 832c50a8f3c3ac71313e2c54ffeca3aab460e63d Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Thu, 18 Jun 2020 08:53:59 +0200
Subject: Delay checking for ad hoc C++ recipe support until match

---
 libbuild2/parser.cxx         | 10 +---------
 libbuild2/rule-adhoc-cxx.cxx | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/libbuild2/parser.cxx b/libbuild2/parser.cxx
index 6d34a11..21b5794 100644
--- a/libbuild2/parser.cxx
+++ b/libbuild2/parser.cxx
@@ -1143,14 +1143,7 @@ namespace build2
             {
               // C++
               //
-#if defined(BUILD2_BOOTSTRAP) || defined(LIBBUILD2_STATIC_BUILD)
-              fail (loc) << "ad hoc c++ recipe" <<
-#ifdef BUILD2_BOOTSTRAP
-                info << "running bootstrap build system";
-#else
-                info << "running statically-linked build system";
-#endif
-#else
+
               // Parse recipe version and optional fragment separator.
               //
               if (tt == type::newline || tt == type::eos)
@@ -1195,7 +1188,6 @@ namespace build2
 
               ar.reset (
                 new adhoc_cxx_rule (loc, st.value.size (), ver, move (sep)));
-#endif // BUILD2_BOOTSTRAP || LIBBUILD2_STATIC_BUILD
             }
             else
               fail (lloc) << "unknown recipe language '" << *lang << "'";
diff --git a/libbuild2/rule-adhoc-cxx.cxx b/libbuild2/rule-adhoc-cxx.cxx
index 547bb69..1159a17 100644
--- a/libbuild2/rule-adhoc-cxx.cxx
+++ b/libbuild2/rule-adhoc-cxx.cxx
@@ -61,6 +61,24 @@ namespace build2
        << ind << string (braces, '}');
   }
 
+#if defined(BUILD2_BOOTSTRAP) || defined(LIBBUILD2_STATIC_BUILD)
+  bool adhoc_cxx_rule::
+  match (action, target&, const string&) const
+  {
+    // Note that we wait until match() (instead of, say, failing in the
+    // parser) to allow the presence of ad hoc C++ recipes for other
+    // operations.
+    //
+    fail (loc) << "ad hoc c++ recipe" <<
+#ifdef BUILD2_BOOTSTRAP
+      info << "running bootstrap build system" << endf;
+#else
+      info << "running statically-linked build system" << endf;
+#endif
+  }
+
+#else
+
   // From module.cxx.
   //
   void
@@ -637,6 +655,7 @@ namespace build2
 
     return impl->match (a, t, hint);
   }
+#endif // BUILD2_BOOTSTRAP || LIBBUILD2_STATIC_BUILD
 
   recipe adhoc_cxx_rule::
   apply (action a, target& t) const
-- 
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