elemental2 is broken on bazel 9 due to gwt dep

[aschleck]

Thank you for making this amazing ecosystem!

elemental2 depends on the gwt project as an http_archive (

elemental2/MODULE.bazel

Line 54 in 59747da

name = "org_gwtproject_gwt",

) for the GWT array stamper (used here

elemental2/java/elemental2/core/BuiltInClosureTypeCleaner.java

Line 204 in 59747da

.setInvocationTarget(new TypeQualifier(ARRAY_STAMPER.getReference(false)))

pulled from

elemental2/third_party/BUILD

Line 327 in 59747da

"@org_gwtproject_gwt//user:super/com/google/gwt/emul/javaemul/internal/ArrayStamper.java",

)

However, as of Bazel 9, the gwt repo needs some additional build rules. I made a gwt repo PR in gwtproject/gwt#10349 but the maintainer doesn't seem inclined to accept the patch. Do you have any thoughts on how to get this fixed? Whether getting that patch committed or forking the code into elemental2 like the gwt maintainer seems to be expecting?

In the meantime I've been patching elemental2 in my root MODULE.bazel but it feels bad: https://github.com/aschleck/trailcatalog/blob/main/MODULE.bazel#L33

[zbynek]

If the goal is just to have a version of ArrayStamper on the classpath, it might be possible to take the one from https://github.com/google/j2cl/blob/367ce788ffcac30f7ee05eb687ccb67927dfb2db/jre/java/javaemul/internal/ArrayStamper.java#L21 instead.

[niloc132]

I'm looking into this today, sorry for my delay over at gwtproject/gwt. We don't want to fix this in gwt, as the bazel wiring isn't supported/used, and to my knowledge there is zero GWT+bazel ecosystem. We also have upcoming changes that will restructure the project and break it again, unless we have some dedicated effort to keeping it going.

My impression is that this is just an oversight, and that when J2cl forked the rest of GWT's JRE emulation (including ArrayStamper), other projects such as elemental2 should have moved over as well. As @zbynek said, it almost definitely makes more sense to use the copy from j2cl, since Elemental2 already depends on j2cl. Unfortunately, j2cl doesn't provide those classes for export - ArrayStamper requires JsUtils from the same package, and @UncheckedCast from the javaemul.internals.annotations package. It makes sense, after all these are "internals", and arguably shouldn't be considered a public API. GWT reasonably would want to make the same argument... but then GWT and J2CL couldn't remain (mostly) compatible with jsinterop-annotations, jsinterop-base, and elemental2, so the rules need to be bent somewhere.

This change works if you build elemental2 (or some downstream project) with --check_visibility=false - to do it properly, we probably want to make the existing javaemul.internal target visible publicly (that appears to be jre_java_files, I could reasonably believe that this is too broad), or make a new, more restricted target just for elemental2?

diff --git a/third_party/BUILD b/third_party/BUILD
index 8652bc2..e6a228f 100644
--- a/third_party/BUILD
+++ b/third_party/BUILD
@@ -324,7 +324,12 @@ extern(
 java_library(
     name = "gwt-array-stamper",
     srcs = [
-        "@org_gwtproject_gwt//user:super/com/google/gwt/emul/javaemul/internal/ArrayStamper.java",
+        "@j2cl//jre/java:javaemul/internal/ArrayStamper.java",
+        "@j2cl//jre/java:javaemul/internal/JsUtils.java",
+    ],
+    deps = [
+        "@j2cl//jre/java:javaemul_internal_annotations",
+        "@j2cl//:jsinterop-annotations",
     ],
 )

This change then also lets gwtproject/gwt be removed:

diff --git a/MODULE.bazel b/MODULE.bazel
index d7d5dd8..8469893 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -47,12 +47,3 @@ maven.artifact(
     version = "v20260330",
 )
 use_repo(maven, "maven")
-
-http_archive = use_repo_rule("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
-
-http_archive(
-    name = "org_gwtproject_gwt",
-    sha256 = "731879b8e56024a34f36b83655975a474e1ac1dffdfe72724e337976ac0e1749",
-    strip_prefix = "gwt-073679594c6ead7abe501009f8ba31eb390047fc",
-    url = "https://github.com/gwtproject/gwt/archive/073679594c6ead7abe501009f8ba31eb390047fc.zip",
-)

[gkdn]

If we are not using the original one from GWT and forgo the sanity check for ABI, we can just stub it.

[niloc132]

Here's another option that might work too, if the goal is to still reference GWT code as @gkdn described: the gwt-user jar can be fetched from maven central (as closure-compiler is fetched), and used on the classpath when compiling these types.

diff --git a/MODULE.bazel b/MODULE.bazel
index d7d5dd8..89bdc79 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -46,13 +46,9 @@ maven.artifact(
     group = "com.google.javascript",
     version = "v20260330",
 )
-use_repo(maven, "maven")
-
-http_archive = use_repo_rule("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
-
-http_archive(
-    name = "org_gwtproject_gwt",
-    sha256 = "731879b8e56024a34f36b83655975a474e1ac1dffdfe72724e337976ac0e1749",
-    strip_prefix = "gwt-073679594c6ead7abe501009f8ba31eb390047fc",
-    url = "https://github.com/gwtproject/gwt/archive/073679594c6ead7abe501009f8ba31eb390047fc.zip",
+maven.artifact(
+    artifact = "gwt-user",
+    group = "org.gwtproject",
+    version = "2.13.1",
 )
+use_repo(maven, "maven")
diff --git a/third_party/BUILD b/third_party/BUILD
index 8652bc2..de9cc4d 100644
--- a/third_party/BUILD
+++ b/third_party/BUILD
@@ -321,12 +321,21 @@ extern(
     path = "browser/web_animations.js",
 )
 
-java_library(
+alias(
     name = "gwt-array-stamper",
-    srcs = [
-        "@org_gwtproject_gwt//user:super/com/google/gwt/emul/javaemul/internal/ArrayStamper.java",
-    ],
-)
+    actual = "@maven//:org_gwtproject_gwt_user"
+)

This appears to compile as-is, with no changes to j2cl necessary.

[gkdn]

Yeah I think that should work as well but anyhow I dropped the dep; we don't actively update the GWT dependency in Bazel so if the contract was broken at one point only way to get an alert would be with releases with updated POM so this doesn't change equation much with a stub.

Please let me know if it is working or not.

[aschleck]

This works great for me, thank you!