add_custom_command: Add CODEGEN support

By specifying CODEGEN as an argument to add_custom_command the
custom command will be added to a codegen build target.

The intent is to provide a convenient way for users to get
their generated files without having to build the whole project.

This can be helpful for code analysis tools which can be useful
for IDEs and CI.

1 files changed, 6 insertions, 0 deletions

diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index aa3f28e..e6d56d3 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -4626,6 +4626,12 @@ void AppendCustomCommandToOutput(cmLocalGenerator& lg,
     if (cmCustomCommand* cc = sf->GetCustomCommand()) {
       cc->AppendCommands(commandLines);
       cc->AppendDepends(depends);
+      if (cc->GetCodegen() && !implicit_depends.empty()) {
+        lg.GetCMakeInstance()->IssueMessage(
+          MessageType::FATAL_ERROR,
+          "Cannot append IMPLICIT_DEPENDS to existing CODEGEN custom "
+          "command.");
+      }
       cc->AppendImplicitDepends(implicit_depends);
       return;
     }