fix(dap): skip enrich_config for attach mode (#494)

fobbyal · claude · web-flow · commit ccd76f9eee60 · 2026-06-06T22:45:40.000+05:30
Setup:enrich_config asserts that mainClass is present, but attach
configs don't have one and don't need one — the JVM is already running
and chose its own main class, classpath, and java executable. The
assert fires before any check on request type, making every attach
config in nvim-dap fail unless callers pre-populate dummy values for
the five fields the early-return checks.

Adding an early return for `request == 'attach'` skips the
launch-specific enrichment (build_workspace, classpath resolution,
java executable resolution) which are all meaningless for an already-
running JVM.

Reproduction: register a Java attach config in dap.configurations.java
with type='java', request='attach', hostName='127.0.0.1', port=5005,
then :DapContinue. Today it errors with:

    To enrich the config, mainClass should already be present
    .../java-dap/setup.lua:54

After this fix, the attach proceeds and dap-ui opens against the
running JVM as expected.

Co-authored-by: Claude Opus 4.7 (1M context) &lt;noreply@anthropic.com&gt;
diff --git a/lua/java-dap/setup.lua b/lua/java-dap/setup.lua
@@ -41,6 +41,14 @@ end
 function Setup:enrich_config(config)
 	config = vim.deepcopy(config)
 
+	-- Attach configs don't need enriching — the JVM is already running and
+	-- chose its own main class, classpath, and java executable. Without this
+	-- short-circuit, the `assert(main, ...)` below fires because attach
+	-- configs (correctly) have no mainClass.
+	if config.request == 'attach' then
+		return config
+	end
+
 	-- skip enriching if already enriched
 	if config.mainClass and config.projectName and config.modulePaths and config.classPaths and config.javaExec then
 		return config
