Export: allow exporting of additional properties

This change introduces an additional property that may be set on a
target to allow additional properties to be exported. Normally only a
limited number of properties are exported.

Additional properties may be exported by simply setting the
`EXPORT_PROPERTIES` property on a target that is exported.

4 files changed, 59 insertions, 0 deletions

diff --git a/Source/cmExportBuildFileGenerator.cxx b/Source/cmExportBuildFileGenerator.cxx
index f0ae47b..bbbc998 100644
--- a/Source/cmExportBuildFileGenerator.cxx
+++ b/Source/cmExportBuildFileGenerator.cxx
@@ -97,6 +97,15 @@ bool cmExportBuildFileGenerator::GenerateMainFile(std::ostream& os)
                                     properties, missingTargets);
     this->PopulateInterfaceProperty("INTERFACE_POSITION_INDEPENDENT_CODE", gte,
                                     properties);
+
+    std::string errorMessage;
+    if (!this->PopulateExportProperties(gte, properties, errorMessage)) {
+      this->LG->GetGlobalGenerator()->GetCMakeInstance()->IssueMessage(
+        cmake::FATAL_ERROR, errorMessage,
+        this->LG->GetMakefile()->GetBacktrace());
+      return false;
+    }
+
     const bool newCMP0022Behavior =
       gte->GetPolicyStatusCMP0022() != cmPolicies::WARN &&
       gte->GetPolicyStatusCMP0022() != cmPolicies::OLD;
diff --git a/Source/cmExportFileGenerator.cxx b/Source/cmExportFileGenerator.cxx
index 0f1d745..2dcbfa0 100644
--- a/Source/cmExportFileGenerator.cxx
+++ b/Source/cmExportFileGenerator.cxx
@@ -11,6 +11,8 @@
 #include "cmMakefile.h"
 #include "cmOutputConverter.h"
 #include "cmPolicies.h"
+#include "cmProperty.h"
+#include "cmPropertyMap.h"
 #include "cmStateTypes.h"
 #include "cmSystemTools.h"
 #include "cmTarget.h"
@@ -1097,3 +1099,41 @@ void cmExportFileGenerator::GenerateImportedFileChecksCode(
 
   os << ")\n\n";
 }
+
+bool cmExportFileGenerator::PopulateExportProperties(
+  cmGeneratorTarget* gte, ImportPropertyMap& properties,
+  std::string& errorMessage)
+{
+  auto& targetProperties = gte->Target->GetProperties();
+  const auto& exportProperties = targetProperties.find("EXPORT_PROPERTIES");
+  if (exportProperties != targetProperties.end()) {
+    std::vector<std::string> propsToExport;
+    cmSystemTools::ExpandListArgument(exportProperties->second.GetValue(),
+                                      propsToExport);
+    for (auto& prop : propsToExport) {
+      /* Black list reserved properties */
+      if (cmSystemTools::StringStartsWith(prop, "IMPORTED_") ||
+          cmSystemTools::StringStartsWith(prop, "INTERFACE_")) {
+        std::ostringstream e;
+        e << "Target \"" << gte->Target->GetName() << "\" contains property \""
+          << prop << "\" in EXPORT_PROPERTIES but IMPORTED_* and INTERFACE_* "
+          << "properties are reserved.";
+        errorMessage = e.str();
+        return false;
+      }
+      auto propertyValue = targetProperties.GetPropertyValue(prop);
+      std::string evaluatedValue = cmGeneratorExpression::Preprocess(
+        propertyValue, cmGeneratorExpression::StripAllGeneratorExpressions);
+      if (evaluatedValue != propertyValue) {
+        std::ostringstream e;
+        e << "Target \"" << gte->Target->GetName() << "\" contains property \""
+          << prop << "\" in EXPORT_PROPERTIES but this property contains a "
+          << "generator expression. This is not allowed.";
+        errorMessage = e.str();
+        return false;
+      }
+      properties[prop] = propertyValue;
+    }
+  }
+  return true;
+}
diff --git a/Source/cmExportFileGenerator.h b/Source/cmExportFileGenerator.h
index e541372..954e6c5 100644
--- a/Source/cmExportFileGenerator.h
+++ b/Source/cmExportFileGenerator.h
@@ -168,6 +168,10 @@ protected:
   virtual void GenerateRequiredCMakeVersion(std::ostream& os,
                                             const char* versionString);
 
+  bool PopulateExportProperties(cmGeneratorTarget* gte,
+                                ImportPropertyMap& properties,
+                                std::string& errorMessage);
+
   // The namespace in which the exports are placed in the generated file.
   std::string Namespace;
 
diff --git a/Source/cmExportInstallFileGenerator.cxx b/Source/cmExportInstallFileGenerator.cxx
index 93ba2ce..63d04a6 100644
--- a/Source/cmExportInstallFileGenerator.cxx
+++ b/Source/cmExportInstallFileGenerator.cxx
@@ -104,6 +104,12 @@ bool cmExportInstallFileGenerator::GenerateMainFile(std::ostream& os)
                                     cmGeneratorExpression::InstallInterface,
                                     properties, missingTargets);
 
+    std::string errorMessage;
+    if (!this->PopulateExportProperties(gt, properties, errorMessage)) {
+      cmSystemTools::Error(errorMessage.c_str());
+      return false;
+    }
+
     const bool newCMP0022Behavior =
       gt->GetPolicyStatusCMP0022() != cmPolicies::WARN &&
       gt->GetPolicyStatusCMP0022() != cmPolicies::OLD;