cmTarget: Simplify INTERFACE_SOURCES usage requirement lookup

Use the AddInterfaceEntries helper to avoid duplication.

Source/cmTarget.cxx

@@ -774,45 +774,9 @@ void cmTarget::GetSourceFiles(std::vector<std::string> &files,
 
   if (!this->Internal->CacheLinkInterfaceSourcesDone[config])
     {
-    for (std::vector<cmValueWithOrigin>::const_iterator
+    this->Internal->AddInterfaceEntries(
-        it = this->Internal->LinkImplementationPropertyEntries.begin(),
+      this, config, "INTERFACE_SOURCES",
-        end = this->Internal->LinkImplementationPropertyEntries.end();
+      this->Internal->CachedLinkInterfaceSourcesEntries[config]);
-        it != end; ++it)
-      {
-      if (!cmGeneratorExpression::IsValidTargetName(it->Value)
-          && cmGeneratorExpression::Find(it->Value) == std::string::npos)
-        {
-        continue;
-        }
-      {
-      cmGeneratorExpression ge;
-      cmsys::auto_ptr<cmCompiledGeneratorExpression> cge =
-                                                        ge.Parse(it->Value);
-      std::string targetResult = cge->Evaluate(this->Makefile, config,
-                                        false, this, 0, &dagChecker);
-      if (!this->Makefile->FindTargetToUse(targetResult))
-        {
-        continue;
-        }
-      }
-      std::string sourceGenex = "$<TARGET_PROPERTY:" +
-                              it->Value + ",INTERFACE_SOURCES>";
-      if (cmGeneratorExpression::Find(it->Value) != std::string::npos)
-        {
-        // Because it->Value is a generator expression, ensure that it
-        // evaluates to the non-empty string before being used in the
-        // TARGET_PROPERTY expression.
-        sourceGenex = "$<$<BOOL:" + it->Value + ">:" + sourceGenex + ">";
-        }
-      cmGeneratorExpression ge(&it->Backtrace);
-      cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(
-                                                                sourceGenex);
-
-      this->Internal
-        ->CachedLinkInterfaceSourcesEntries[config].push_back(
-                        new cmTargetInternals::TargetPropertyEntry(cge,
-                                                              it->Value));
-      }
     }
 
     std::vector<std::string>::size_type numFilesBefore = files.size();

Tests/RunCMake/Languages/LINK_LANGUAGE-genex-stderr.txt

@@ -1,7 +1,9 @@
-CMake Error:
+CMake Error at LINK_LANGUAGE-genex.cmake:[0-9]+ \(target_link_libraries\):
   Error evaluating generator expression:
 
     \$<TARGET_PROPERTY:LINKER_LANGUAGE>
 
   LINKER_LANGUAGE target property can not be used while evaluating link
-  libraries
+  libraries for a static library
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)

Tests/RunCMake/Languages/link-libraries-TARGET_FILE-genex-stderr.txt

@@ -1,7 +1,9 @@
-CMake Error:
+CMake Error at link-libraries-TARGET_FILE-genex.cmake:[0-9]+ \(target_link_libraries\):
   Error evaluating generator expression:
 
     \$<TARGET_FILE:foo>
 
   Expressions which require the linker language may not be used while
   evaluating link libraries
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)