cider-macroexpand: Bind LOADER if unbound

Author: vemv

.circleci/config.yml

@@ -85,6 +85,8 @@ commands:
       - save_cache:
           paths:
             - ~/.m2
+            - linux-install-1.10.3.1040.sh
+            - clojure-tools-1.10.3.1040.tar.gz
             - .cpcache
           key: clojure-<< parameters.cache_version >>-{{ checksum "/tmp/clojure_cache_seed" }}
 
@@ -131,6 +133,18 @@ jobs:
             - run:
                 name: Running tests with inlined deps
                 command: make test smoketest
+            - run:
+                name: Install the Clojure CLI
+                command: |
+                  # the `nc` option skips downloading a file as already present
+                  # (as allowed by the Circle caching).
+                  wget -nc https://download.clojure.org/install/linux-install-1.10.3.1040.sh
+                  sed -i 's/curl -O/wget -nc/g' linux-install-1.10.3.1040.sh
+                  chmod +x linux-install-1.10.3.1040.sh
+                  sudo ./linux-install-1.10.3.1040.sh
+            - run:
+                name: Running tests specific to tools.deps
+                command: make tools-deps-test
 
 ######################################################################
 #

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Bugs fixed
 
+* [#721](https://github.com/clojure-emacs/cider-nrepl/issues/721): `middleware.macroexpand`: support a corner case for tools.deps.
 * [#735](https://github.com/clojure-emacs/cider-nrepl/issues/735): `middleware.test.extensions`: make `:actual` reporting clearer.
 * [#737](https://github.com/clojure-emacs/cider-nrepl/pull/737): Fix a regression in `middleware.out` that could result in duplicate output.
 

Makefile

@@ -11,12 +11,15 @@ test/resources/cider/nrepl/clojuredocs/export.edn:
 
 inline-deps: .inline-deps
 
-test: .inline-deps test/resources/cider/nrepl/clojuredocs/export.edn
+test: clean .inline-deps test/resources/cider/nrepl/clojuredocs/export.edn
 	lein with-profile -user,-dev,+$(CLOJURE_VERSION),+test,+plugin.mranderson/config test
 
 quick-test: clean
 	lein with-profile -user,-dev,+$(CLOJURE_VERSION),+test test
 
+tools-deps-test: clean install
+	cd tools-deps-testing; clojure -M:test
+
 eastwood:
 	lein with-profile -user,-dev,+$(CLOJURE_VERSION),+eastwood eastwood
 

src/cider/nrepl/middleware/macroexpand.clj

@@ -113,10 +113,16 @@
   context of the given :ns, using the provided :expander and :display-namespaces
   options."
   [{:keys [code expander ns] :as msg}]
-  (->> (let [expander-fn (resolve-expander-clj expander)]
-         (binding [*ns* (find-ns ns)]
-           (expander-fn (read-string code))))
-       (walk/prewalk (post-expansion-walker-clj msg))))
+  ;; Bind LOADER, which can be unbound under certain code paths, particularly when using tools.deps:
+  (with-bindings {clojure.lang.Compiler/LOADER
+                  (if (instance? clojure.lang.Var$Unbound
+                                 @clojure.lang.Compiler/LOADER)
+                    (clojure.lang.DynamicClassLoader. (clojure.lang.RT/baseLoader))
+                    @clojure.lang.Compiler/LOADER)}
+    (->> (let [expander-fn (resolve-expander-clj expander)]
+           (binding [*ns* (find-ns ns)]
+             (expander-fn (read-string code))))
+         (walk/prewalk (post-expansion-walker-clj msg)))))
 
 ;; ClojureScript impl
 

tools-deps-testing/deps.edn

@@ -0,0 +1,5 @@
+{:paths ["."]
+ :aliases {:test {:main-opts ["-m" "macroexpand-tools-deps-test"]
+                 :jvm-opts    ["-XX:-OmitStackTraceInFastThrow"
+                               "-Dclojure.main.report=stderr"]}}
+ :deps {cider/cider-nrepl {:mvn/version "RELEASE"}}}

tools-deps-testing/example.clj

@@ -0,0 +1,6 @@
+(ns example)
+
+(defmacro foo []
+  (println (class @clojure.lang.Compiler/LOADER))
+  (assert (not (instance? clojure.lang.Var$Unbound @clojure.lang.Compiler/LOADER)))
+  42)

tools-deps-testing/macroexpand_tools_deps_test.clj

@@ -0,0 +1,9 @@
+(ns macroexpand-tools-deps-test
+  (:require
+   [example]
+   [cider.nrepl.middleware.macroexpand]))
+
+(defn -main [& _]
+  (println (cider.nrepl.middleware.macroexpand/macroexpansion {:ns 'example
+                                                               :code "(foo)"}))
+  (System/exit 0))