From 8f34de5c103e9e4d2c27583020f2975907b626ad Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 22 Aug 2022 11:16:29 +0200
Subject: Manually check values for NULL when using low-level function
 interface

---
 libbuild2/cc/functions.cxx | 12 ++++++++++++
 libbuild2/function.hxx     |  3 ++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/libbuild2/cc/functions.cxx b/libbuild2/cc/functions.cxx
index bba8fbb..94900ee 100644
--- a/libbuild2/cc/functions.cxx
+++ b/libbuild2/cc/functions.cxx
@@ -61,6 +61,9 @@ namespace build2
 
       // We can assume these are present due to function's types signature.
       //
+      if (vs[0].null)
+        throw invalid_argument ("null value");
+
       names& ts_ns (vs[0].as<names> ()); // <targets>
 
       // In a somewhat hackish way strip the outer operation to match how we
@@ -137,6 +140,9 @@ namespace build2
 
       // We can assume this is present due to function's types signature.
       //
+      if (vs[0].null)
+        throw invalid_argument ("null value");
+
       names& ts_ns (vs[0].as<names> ()); // <targets>
 
       optional<linfo> li;
@@ -369,6 +375,9 @@ namespace build2
             bool rel (true);
             if (vs.size () > 2)
             {
+              if (vs[2].null)
+                throw invalid_argument ("null value");
+
               for (const name& f: vs[2].as<names> ())
               {
                 string s (convert<string> (name (f)));
@@ -520,6 +529,9 @@ namespace build2
             // We can assume the argument is present due to function's types
             // signature.
             //
+            if (vs[0].null)
+              throw invalid_argument ("null value");
+
             names& r (vs[0].as<names> ());
             m->deduplicate_export_libs (*bs,
                                         vector<name> (r.begin (), r.end ()),
diff --git a/libbuild2/function.hxx b/libbuild2/function.hxx
index 81ece89..323ac41 100644
--- a/libbuild2/function.hxx
+++ b/libbuild2/function.hxx
@@ -952,7 +952,8 @@ namespace build2
 
     // Low-level interface that can be used to pass additional data.
     //
-    // Note that the call to this function sidesteps the thunk.
+    // Note that the call to this function sidesteps the thunk. One notable
+    // consequence of this is that the values are not checked for NULL.
     //
     template <typename D, typename... A>
     void
-- 
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