Follow all dependencies of shared library private dependencies

In cmComputeLinkDepends we compute the transitive closure of private
shared library dependencies.  When a shared library is added to this
closure we must follow all of its dependencies whether they are private
or public.  Previously we only followed the private dependencies.  Fix
the implementation to follow the public dependencies too.  Also extend
the ExportImport test to cover this case.

Source/cmComputeLinkDepends.cxx

@@ -429,7 +429,8 @@ void cmComputeLinkDepends::HandleSharedDependency(SharedDepEntry const& dep)
     if(cmTarget::LinkInterface const* iface =
        entry.Target->GetLinkInterface(this->Config))
       {
-      // We use just the shared dependencies, not the interface.
+      // Follow public and private dependencies transitively.
+      this->QueueSharedDependencies(index, iface->Libraries);
       this->QueueSharedDependencies(index, iface->SharedDeps);
       }
     }

Tests/ExportImport/Export/CMakeLists.txt

@@ -23,8 +23,13 @@ add_library(testLib1 STATIC testLib1.c)
 add_library(testLib2 STATIC testLib2.c)
 target_link_libraries(testLib2 testLib1)
 
+# Test library with empty link interface.  Link it to an implementation
+# dependency that itself links to dependencies publicly.
+add_library(testLib3ImpDep SHARED testLib3ImpDep.c)
+set_property(TARGET testLib3ImpDep PROPERTY LIBRARY_OUTPUT_DIRECTORY impl/dep)
 add_library(testLib3Imp SHARED testLib3Imp.c)
 set_property(TARGET testLib3Imp PROPERTY LIBRARY_OUTPUT_DIRECTORY impl)
+target_link_libraries(testLib3Imp testLib3ImpDep)
 add_library(testLib3 SHARED testLib3.c)
 target_link_libraries(testLib3 testLib3Imp)
 set_property(TARGET testLib3 PROPERTY LINK_INTERFACE_LIBRARIES "")
@@ -104,6 +109,14 @@ install(
   LIBRARY DESTINATION lib/impl
   ARCHIVE DESTINATION lib/impl
   )
+install(
+  TARGETS
+  testLib3ImpDep
+  EXPORT exp
+  RUNTIME DESTINATION bin
+  LIBRARY DESTINATION lib/impl/dep
+  ARCHIVE DESTINATION lib/impl/dep
+  )
 install(
   TARGETS testLib5
   EXPORT exp
@@ -120,7 +133,7 @@ endif(WIN32)
 
 # Export from build tree.
 export(TARGETS testExe1 testLib1 testLib2 testLib3
-  testExe2libImp testLib3Imp
+  testExe2libImp testLib3Imp testLib3ImpDep
   NAMESPACE bld_
   FILE ExportBuildTree.cmake
   )

Tests/ExportImport/Export/testLib3Imp.c

@@ -1,7 +1,10 @@
 #if defined(_WIN32) || defined(__CYGWIN__)
 # define testLib3Imp_EXPORT __declspec(dllexport)
+# define testLib3ImpDep_IMPORT __declspec(dllimport)
 #else
 # define testLib3Imp_EXPORT
+# define testLib3ImpDep_IMPORT
 #endif
 
-testLib3Imp_EXPORT int testLib3Imp(void) { return 0; }
+testLib3ImpDep_IMPORT int testLib3ImpDep(void);
+testLib3Imp_EXPORT int testLib3Imp(void) { return testLib3ImpDep(); }

Tests/ExportImport/Export/testLib3ImpDep.c

@@ -0,0 +1,7 @@
+#if defined(_WIN32) || defined(__CYGWIN__)
+# define testLib3ImpDep_EXPORT __declspec(dllexport)
+#else
+# define testLib3ImpDep_EXPORT
+#endif
+
+testLib3ImpDep_EXPORT int testLib3ImpDep(void) { return 0; }