cmLinkItem: Convert to a "sum type" over a string and target pointer

Avoid exposing the item name implicitly as std::string.  When the item
is a target, avoid storing a second copy of its name.

Most link item construction is paired with calls to `FindTargetToLink`
to get the possible target pointer.  Rename these methods to
`ResolveLinkItem` and refactor them to construct the entire item.

1 files changed, 11 insertions, 1 deletions

diff --git a/Source/cmExportFileGenerator.cxx b/Source/cmExportFileGenerator.cxx
index 75d3374287..1c5040abe3 100644
--- a/Source/cmExportFileGenerator.cxx
+++ b/Source/cmExportFileGenerator.cxx
@@ -831,6 +831,16 @@ void cmExportFileGenerator::SetImportDetailProperties(
   }
 }
 
+static std::string const& asString(std::string const& l)
+{
+  return l;
+}
+
+static std::string const& asString(cmLinkItem const& l)
+{
+  return l.AsStr();
+}
+
 template <typename T>
 void cmExportFileGenerator::SetImportLinkProperty(
   std::string const& suffix, cmGeneratorTarget* target,
@@ -850,7 +860,7 @@ void cmExportFileGenerator::SetImportLinkProperty(
     link_entries += sep;
     sep = ";";
 
-    std::string temp = l;
+    std::string temp = asString(l);
     this->AddTargetNamespace(temp, target, missingTargets);
     link_entries += temp;
   }