Handle config.import.*.<name>.lib in cc::search_library()

In particular, this provides support for using prefixed/suffixed installed
libraries (GH issue #449).

3 files changed, 114 insertions, 57 deletions

diff --git a/NEWS b/NEWS
index 1c285c7..bc00177 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,32 @@
+Version 0.18.0
+
+  * Ability to override imported installed library path/name.
+
+    Specifically, the config.import.<proj>.<name>.{lib,liba,libs} variables
+    can be used to specify alternative location and/or name for an installed
+    library. This, in particular, can be useful when trying to use a library
+    installed with a prefix or suffix. For example, if the library was
+    installed with the `D` suffix:
+
+    config.import.libfoo.foo.lib=fooD
+
+    For the config.*.lib variable, the valid values are a simple path (which
+    is used as a library name base), an absolute directory (which is used as a
+    library location), or both. For example:
+
+    config.import.libfoo.foo.lib=/tmp/lib/
+    config.import.libfoo.foo.lib=/tmp/lib/fooD
+
+    For the config.*.{liba,libs} variables, the valid values are a simple name
+    (which is used as a library name), or an absolute path (which is used as a
+    library location and name). For example:
+
+    config.import.libfoo.foo.libs=libfooD.so
+    config.import.libfoo.foo.liba=/tmp/lib/libfooD.a
+
+    Note that on Windows, the shared library name/path should refer to the
+    import library, not the DLL.
+
 Version 0.17.0
 
   * C++20 modules support improvements:
diff --git a/libbuild2/cc/common.cxx b/libbuild2/cc/common.cxx
index 0589c30..ae89a85 100644
--- a/libbuild2/cc/common.cxx
+++ b/libbuild2/cc/common.cxx
@@ -950,22 +950,35 @@ namespace build2
                     const prerequisite_key& p,
                     bool exist) const
     {
+      assert (p.scope != nullptr && (!exist || act));
+
       tracer trace (x, "search_library");
 
-      assert (p.scope != nullptr && (!exist || act));
+      context& ctx (p.scope->ctx);
+      const scope& rs (*p.scope->root_scope ());
 
-      // Import phase 1 may pass us a user-specified path with a relative
-      // directory (same semantics as in lookup_import() below).
+      // Note: since we are searching for a (presumably) installed library,
+      // utility libraries do not apply.
       //
-      {
-        const dir_path& d (*p.tk.dir);
+      bool l (p.is_a<lib> ());
+      const string& name (*p.tk.name);
+      const optional<string>& ext (l ? nullopt : p.tk.ext); // Only liba/libs.
 
-        if (!d.empty ())
-          fail << "relative path in imported " << p;
-      }
+      // Import phase 1 may pass us a path specified by the user with
+      // config.import.<proj>.<name>.<type>. The possible cases are:
+      //
+      // 1. Empty or relative directory for liba{} and libs{} (absolute would
+      //    be taken care of by phase 1 since these tragets are path-based).
+      //
+      // 2. Empty, relative, or absolute directory for lib{} (since it's not a
+      //    path-based target).
+      //
+      const dir_path& dir (*p.tk.dir);
 
-      context& ctx (p.scope->ctx);
-      const scope& rs (*p.scope->root_scope ());
+      // Same semantics as in lookup_import() below.
+      //
+      if (!dir.empty () && dir.relative ())
+        fail << "relative path in imported " << p;
 
       // Here is the problem: we may be building for two different toolchains
       // simultaneously that use the same installed library. But our search is
@@ -977,17 +990,6 @@ namespace build2
                               ? cpath
                               : cast<process_path> (rs["bin.ld.path"]));
 
-      // @@ This is hairy enough to warrant a separate implementation for
-      //    Windows.
-
-      // Note: since we are searching for a (presumably) installed library,
-      // utility libraries do not apply.
-      //
-      bool l (p.is_a<lib> ());
-      const optional<string>& ext (l ? nullopt : p.tk.ext); // Only liba/libs.
-
-      const string& name (*p.tk.name);
-
       // If this prerequisite is project-qualified do an ad hoc check for
       // config.import.<proj>.<name>.{liba,libs} which can be used to specify
       // different path (see import_search() for background). Note that for
@@ -1106,14 +1108,16 @@ namespace build2
           //
           const char* e ("");
 
+          an = dir; // Empty or absolute.
+
           if (tsys == "win32-msvc")
           {
-            an = path (name);
+            an /= path (name);
             e = "lib";
           }
           else
           {
-            an = path ("lib" + name);
+            an /= path ("lib" + name);
             e = "a";
           }
 
@@ -1142,14 +1146,16 @@ namespace build2
         {
           const char* e ("");
 
+          sn = dir;
+
           if (tsys == "win32-msvc")
           {
-            sn = path (name);
+            sn /= path (name);
             e = "dll.lib";
           }
           else
           {
-            sn = path ("lib" + name);
+            sn /= path ("lib" + name);
 
             if      (tsys == "darwin")  e = "dylib";
             else if (tsys == "mingw32") e = "dll.a"; // See search code below.
diff --git a/libbuild2/file.cxx b/libbuild2/file.cxx
index 8e3b2a4..a6b62c0 100644
--- a/libbuild2/file.cxx
+++ b/libbuild2/file.cxx
@@ -2359,8 +2359,19 @@ namespace build2
           {
             string on (move (tgt.value)); // Original name as imported.
 
-            tgt.dir = p->directory ();
-            tgt.value = p->leaf ().string ();
+            // Keep the original name if the path is (syntactically) to
+            // directory.
+            //
+            if (p->to_directory ())
+            {
+              tgt.dir = path_cast<dir_path> (*p);
+              tgt.value = on;
+            }
+            else
+            {
+              tgt.dir = p->directory ();
+              tgt.value = p->leaf ().string ();
+            }
 
             // If the path is relative, then keep it project-qualified
             // assuming import phase 2 knows what to do with it. Think:
@@ -2379,48 +2390,59 @@ namespace build2
               tgt.proj = move (proj);
             else
             {
-              // Enter the target and assign its path (this will most commonly
-              // be some out of project file).
-              //
-              // @@ Should we check that the file actually exists (and cache
-              //    the extracted timestamp)? Or just let things take their
-              //    natural course?
-              //
               name n (tgt);
               const target_type* tt (ibase.find_target_type (n, loc).first);
 
               if (tt == nullptr)
                 fail (loc) << "unknown target type " << n.type << " in " << n;
 
-              // Note: not using the extension extracted by find_target_type()
-              // to be consistent with import phase 2.
-              //
-              target& t (insert_target (trace, ctx, *tt, *p).first);
-
-              // Load the metadata, similar to import phase 2.
+              // If this is not a path-based target, then delegate to import
+              // phase 2 as above (see cc::search_library() for an example).
               //
-              if (meta)
+              if (!tt->is_a<path_target> ())
               {
-                if (exe* e = t.is_a<exe> ())
+                tgt.proj = move (proj);
+              }
+              else
+              {
+                // Enter the target and assign its path (this will most
+                // commonly be some out of project file).
+                //
+                // @@ Should we check that the file actually exists (and cache
+                //    the extracted timestamp)? Or just let things take their
+                //    natural course?
+                //
+
+                // Note: not using the extension extracted by
+                // find_target_type() to be consistent with import phase 2.
+                //
+                target& t (insert_target (trace, ctx, *tt, *p).first);
+
+                // Load the metadata, similar to import phase 2.
+                //
+                if (meta)
                 {
-                  if (!e->vars[ctx.var_export_metadata].defined ())
+                  if (exe* e = t.is_a<exe> ())
                   {
-                    optional<string> md;
+                    if (!e->vars[ctx.var_export_metadata].defined ())
                     {
-                      auto df = make_diag_frame (
-                        [&proj, tt, &on] (const diag_record& dr)
-                        {
-                          import_suggest (
-                            dr, proj, tt, on, false, "alternative ");
-                        });
-
-                      md = extract_metadata (e->process_path (),
-                                             *meta,
-                                             false /* optional */,
-                                             loc);
+                      optional<string> md;
+                      {
+                        auto df = make_diag_frame (
+                          [&proj, tt, &on] (const diag_record& dr)
+                          {
+                            import_suggest (
+                              dr, proj, tt, on, false, "alternative ");
+                          });
+
+                        md = extract_metadata (e->process_path (),
+                                               *meta,
+                                               false /* optional */,
+                                               loc);
+                      }
+
+                      parse_metadata (*e, move (*md), loc);
                     }
-
-                    parse_metadata (*e, move (*md), loc);
                   }
                 }
               }