Fix export of STATIC library PRIVATE non-target dependencies

In commit v3.5.0-rc1~43^2 (Fix export of STATIC library PRIVATE
dependencies with CMP0022 NEW, 2016-01-15) we taught
target_link_libraries to generate `$<LINK_ONLY:$<TARGET_NAME:dep>>` in
INTERFACE_LINK_LIBRARIES instead of `$<LINK_ONLY:dep>` so that `dep` can
be recognized as a target name and updated during export.  However, this
approach does not work when `dep` is just a plain library name and not a
target because `$<TARGET_NAME:...>` requires the name of a reachable
target.

Since we do not know during target_link_libraries whether the name will
correspond to a reachable target or not, we cannot inject the
`$<TARGET_NAME:...>` expression.  Revert this change and solve the
original problem instead by teaching the export logic to recognize and
update target names directly in `$<LINK_ONLY:...>` expressions.

Reported-by: Ben Boeckel <ben.boeckel@kitware.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/Source/cmExportFileGenerator.cxx b/Source/cmExportFileGenerator.cxx
index e8a2e6a..c005995 100644
--- a/Source/cmExportFileGenerator.cxx
+++ b/Source/cmExportFileGenerator.cxx
@@ -772,6 +772,27 @@ cmExportFileGenerator::ResolveTargetsInGeneratorExpression(
     lastPos = endPos;
     }
 
+  pos = 0;
+  lastPos = pos;
+  while (errorString.empty() &&
+         (pos = input.find("$<LINK_ONLY:", lastPos)) != input.npos)
+    {
+    std::string::size_type nameStartPos = pos + sizeof("$<LINK_ONLY:") - 1;
+    std::string::size_type endPos = input.find(">", nameStartPos);
+    if (endPos == input.npos)
+      {
+      errorString = "$<LINK_ONLY:...> expression incomplete";
+      break;
+      }
+    std::string libName = input.substr(nameStartPos, endPos - nameStartPos);
+    if (cmGeneratorExpression::IsValidTargetName(libName) &&
+        this->AddTargetNamespace(libName, target, missingTargets))
+      {
+      input.replace(nameStartPos, endPos - nameStartPos, libName);
+      }
+    lastPos = nameStartPos + libName.size() + 1;
+    }
+
   this->ReplaceInstallPrefix(input);
 
   if (!errorString.empty())