From 6feaa13453d5071f340f405075c3ea880dc23ac1 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Thu, 18 Oct 2018 11:30:15 +0200
Subject: Fix bug in binless library linking logic

---
 build2/cc/link-rule.cxx | 16 +++++-----------
 build2/cc/pkgconfig.cxx | 11 +++--------
 build2/target.hxx       | 16 ++++++++--------
 3 files changed, 16 insertions(+), 27 deletions(-)

diff --git a/build2/cc/link-rule.cxx b/build2/cc/link-rule.cxx
index 93cdecf..1dd8726 100644
--- a/build2/cc/link-rule.cxx
+++ b/build2/cc/link-rule.cxx
@@ -1206,7 +1206,7 @@ namespace build2
             if (!lu)
               return;
 
-            if (l->path ().empty ()) // Binless.
+            if (l->mtime () == timestamp_unreal) // Binless.
               return;
 
             for (const target* pt: l->prerequisite_targets[d.a])
@@ -1238,10 +1238,7 @@ namespace build2
             // Linking a library to a shared library or executable.
             //
 
-            // Note: on Windows shared library could be the DLL with unknown
-            // location (empty path). See search_library() for details.
-            //
-            if (l->path ().empty () && l->member == nullptr) // Binless.
+            if (l->mtime () == timestamp_unreal) // Binless.
               return;
 
             // On Windows a shared library is a DLL with the import library as
@@ -1352,10 +1349,7 @@ namespace build2
           if (d.li.type == otype::a && !lu)
             return;
 
-          // Note: on Windows shared library could be the DLL with unknown
-          // location (empty path). See search_library() for details.
-          //
-          if (l->path ().empty () && l->member == nullptr) // Binless.
+          if (l->mtime () == timestamp_unreal) // Binless.
             return;
 
           // Check if this library renders us out of date.
@@ -1459,7 +1453,7 @@ namespace build2
           if (!l->is_a<libs> ())
             return;
 
-          if (l->path ().empty ()) // Binless.
+          if (l->mtime () == timestamp_unreal) // Binless.
             return;
         }
         else
@@ -2250,7 +2244,7 @@ namespace build2
 
       args[0] = ld->recall_string ();
 
-      // The same logic as during hashing above.
+      // Append input files. The same logic as during hashing above.
       //
       // See also a similar loop inside append_libraries().
       //
diff --git a/build2/cc/pkgconfig.cxx b/build2/cc/pkgconfig.cxx
index a752348..26b0aea 100644
--- a/build2/cc/pkgconfig.cxx
+++ b/build2/cc/pkgconfig.cxx
@@ -1093,14 +1093,9 @@ namespace build2
       // the saving logic).
       //
       pkgconf& ipc (sp.empty () ? apc : spc); // Interface package info.
-      bool ibl (sp.empty () // Binless.
-                ? at->path ().empty ()
-                //
-                // On Windows the shared library could be a DLL with an empty
-                // path (unknown location) and an ad hoc member that is the
-                // import library. See search_library() for details.
-                //
-                : st->path ().empty () && st->member == nullptr);
+      bool ibl ((sp.empty ()
+                 ? at->mtime ()
+                 : st->mtime ()) == timestamp_unreal); // Binless.
 
       bool pa (at != nullptr && !ap.empty ());
       if (pa || sp.empty ())
diff --git a/build2/target.hxx b/build2/target.hxx
index 1249f5c..d73a98c 100644
--- a/build2/target.hxx
+++ b/build2/target.hxx
@@ -1447,14 +1447,14 @@ namespace build2
     // any time but any subsequent updates must set the same path. Or, in
     // other words, once the path is set, it never changes.
     //
-    // A set empty path may signify special unknown/undetermined location (for
-    // example an installed import library -- we know it's there, just not
-    // exactly where). In this case you would also normally set its mtime. We
-    // used to return a pointer to properly distinguish between not set and
-    // empty but that proved too tedious. Note that this means there could be
-    // a race between path and mtime (unless you lock the target in some other
-    // way; see file_rule) so for this case it makes sense to set the
-    // timestamp first.
+    // A set empty path may signify special unknown/undetermined/unreal
+    // location (for example, a binless library or an installed import library
+    // -- we know the DLL is there, just not exactly where). In this case you
+    // would also normally set its mtime. We used to return a pointer to
+    // properly distinguish between not set and empty but that proved too
+    // tedious. Note that this means there could be a race between path and
+    // mtime (unless you lock the target in some other way; see file_rule) so
+    // for this case it makes sense to set the timestamp first.
     //
     const path_type&
     path () const;
-- 
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