cmTarget: Raise error if imported target location is not set

Previously we would synthesize <TARGET_NAME>-NOTFOUND as the location. This
would then end up on the link line and cause build failures.
Policy CMP0110 is added to control this behaviour.

Fixes #19080, #19943.

1 files changed, 31 insertions, 0 deletions

diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index 60416a3..bea9001 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -2039,6 +2039,37 @@ std::string cmTarget::ImportedGetFullPath(
   }
 
   if (result.empty()) {
+    auto message = [&]() -> std::string {
+      std::string unset;
+      std::string configuration;
+
+      if (artifact == cmStateEnums::RuntimeBinaryArtifact) {
+        unset = "IMPORTED_LOCATION";
+      } else if (artifact == cmStateEnums::ImportLibraryArtifact) {
+        unset = "IMPORTED_IMPLIB";
+      }
+
+      if (!config.empty()) {
+        configuration = cmStrCat(" configuration \"", config, "\"");
+      }
+
+      return cmStrCat(unset, " not set for imported target \"",
+                      this->GetName(), "\"", configuration, ".");
+    };
+
+    switch (this->GetPolicyStatus(cmPolicies::CMP0111)) {
+      case cmPolicies::WARN:
+        impl->Makefile->IssueMessage(
+          MessageType::AUTHOR_WARNING,
+          cmPolicies::GetPolicyWarning(cmPolicies::CMP0111) + "\n" +
+            message());
+        CM_FALLTHROUGH;
+      case cmPolicies::OLD:
+        break;
+      default:
+        impl->Makefile->IssueMessage(MessageType::FATAL_ERROR, message());
+    }
+
     result = cmStrCat(this->GetName(), "-NOTFOUND");
   }
   return result;