From 54a0c41081f2bfd11054c3e7456b6ab4a915f28f Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 2 Aug 2023 09:58:28 +0200
Subject: Diagnose declarations of targets/prerequisites with abstract target
 types

---
 libbuild2/parser.cxx | 25 +++++++++++++++++++++++++
 libbuild2/target.hxx |  2 +-
 2 files changed, 26 insertions(+), 1 deletion(-)

(limited to 'libbuild2')

diff --git a/libbuild2/parser.cxx b/libbuild2/parser.cxx
index 5d77e2b..9ced841 100644
--- a/libbuild2/parser.cxx
+++ b/libbuild2/parser.cxx
@@ -172,6 +172,10 @@ namespace build2
                    tracer& tr)
     {
       auto r (p.scope_->find_target_type (n, o, loc));
+
+      if (r.first.factory == nullptr)
+        p.fail (loc) << "abstract target type " << r.first.name << "{}";
+
       return p.ctx->targets.insert (
         r.first,         // target type
         move (n.dir),
@@ -192,6 +196,10 @@ namespace build2
                  tracer& tr)
     {
       auto r (p.scope_->find_target_type (n, o, loc));
+
+      if (r.first.factory == nullptr)
+        p.fail (loc) << "abstract target type " << r.first.name << "{}";
+
       return p.ctx->targets.find (r.first,  // target type
                                   n.dir,
                                   o.dir,
@@ -916,6 +924,8 @@ namespace build2
 
           // Resolve target type. If none is specified, then it's file{}.
           //
+          // Note: abstract target type is ok here.
+          //
           const target_type* ttype (n.untyped ()
                                     ? &file::static_type
                                     : scope_->find_target_type (n.type));
@@ -2765,6 +2775,9 @@ namespace build2
       if (t == nullptr)
         fail (ploc) << "unknown target type " << n.type;
 
+      if (t->factory == nullptr)
+        fail (ploc) << "abstract target type " << t->name << "{}";
+
       // Current dir collapses to an empty one.
       //
       if (!n.dir.empty ())
@@ -4328,6 +4341,13 @@ namespace build2
       if (bt == nullptr)
         fail (t) << "unknown target type " << bn;
 
+      // The derive_target_type() call below does not produce a non-abstract
+      // type if passed an abstract base. So we ban this for now (it's unclear
+      // why would someone want to do this).
+      //
+      if (bt->factory == nullptr)
+        fail (t) << "abstract base target type " << bt->name << "{}";
+
       // Note that the group{foo}<...> syntax is only recognized for group-
       // based targets and ad hoc buildscript recipes/rules only match group.
       // (We may want to relax this for member_hint in the future since its
@@ -7521,6 +7541,8 @@ namespace build2
 
               if (ttp == nullptr)
                 ppat = pinc = false;
+              else if (ttp->factory == nullptr)
+                fail (loc) << "abstract target type " << ttp->name << "{}";
             }
           }
 
@@ -7682,6 +7704,9 @@ namespace build2
                                         ? scope_->find_target_type (*tp)
                                         : nullptr);
 
+                if (ttp != nullptr && ttp->factory == nullptr)
+                  fail (loc) << "abstract target type " << ttp->name << "{}";
+
                 if (tp == nullptr || ttp != nullptr)
                 {
                   if (pmode == pattern_mode::detect)
diff --git a/libbuild2/target.hxx b/libbuild2/target.hxx
index 79ec9fa..99383e7 100644
--- a/libbuild2/target.hxx
+++ b/libbuild2/target.hxx
@@ -2413,7 +2413,7 @@ namespace build2
   // in the generic install rule. @@ This is still a TODO.
   //
   // Note that handling subsections with man1..9{} is easy, we
-  // simply specify the extension explicitly, e.g., man{foo.1p}.
+  // simply specify the extension explicitly, e.g., man1{foo.1p}.
   //
   class LIBBUILD2_SYMEXPORT man: public doc
   {
-- 
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