cmExportPackageInfoGenerator: Fix version properties

Fix a small bug in cmExportPackageInfoGenerator that caused extended
version properties ("compat_version", "version_schema")) to be emitted
when empty. Add a test to ensure this is working as intended.

Fixes: #26264

Source/cmExportPackageInfoGenerator.cxx

@@ -106,10 +106,10 @@ Json::Value cmExportPackageInfoGenerator::GeneratePackageInfo() const
 
   if (!this->PackageVersion.empty()) {
     package["version"] = this->PackageVersion;
-    if (!this->PackageVersion.empty()) {
+    if (!this->PackageVersionCompat.empty()) {
       package["compat_version"] = this->PackageVersionCompat;
     }
-    if (!this->PackageVersion.empty()) {
+    if (!this->PackageVersionSchema.empty()) {
       package["version_schema"] = this->PackageVersionSchema;
     }
   }

Tests/RunCMake/PackageInfo/MinimalVersion-check.cmake

@@ -0,0 +1,21 @@
+include(${CMAKE_CURRENT_LIST_DIR}/Assertions.cmake)
+
+set(out_dir "${RunCMake_BINARY_DIR}/MinimalVersion-build/CMakeFiles/Export/510c5684a4a8a792eadfb55bc9744983")
+
+file(READ "${out_dir}/foo1.cps" content)
+expect_value("${content}" "foo1" "name")
+expect_value("${content}" "1.0" "version")
+expect_missing("${content}" "compat_version")
+expect_missing("${content}" "version_schema")
+
+file(READ "${out_dir}/foo2.cps" content)
+expect_value("${content}" "foo2" "name")
+expect_value("${content}" "1.5" "version")
+expect_value("${content}" "1.0" "compat_version")
+expect_missing("${content}" "version_schema")
+
+file(READ "${out_dir}/foo3.cps" content)
+expect_value("${content}" "foo3" "name")
+expect_value("${content}" "1.0" "version")
+expect_missing("${content}" "compat_version")
+expect_value("${content}" "simple" "version_schema")

Tests/RunCMake/PackageInfo/MinimalVersion.cmake

@@ -0,0 +1,19 @@
+add_library(foo INTERFACE)
+install(TARGETS foo EXPORT foo DESTINATION .)
+
+install(PACKAGE_INFO foo1
+  EXPORT foo
+  VERSION 1.0
+  DESTINATION cps)
+
+install(PACKAGE_INFO foo2
+  EXPORT foo
+  VERSION 1.5
+  COMPAT_VERSION 1.0
+  DESTINATION cps)
+
+install(PACKAGE_INFO foo3
+  EXPORT foo
+  VERSION 1.0
+  VERSION_SCHEMA simple
+  DESTINATION cps)

Tests/RunCMake/PackageInfo/RunCMakeTest.cmake

@@ -27,6 +27,7 @@ run_cmake(Appendix)
 run_cmake(InterfaceProperties)
 run_cmake(Metadata)
 run_cmake(Minimal)
+run_cmake(MinimalVersion)
 run_cmake(LowerCaseFile)
 run_cmake(Requirements)
 run_cmake(TargetTypes)