athlcode commented on code in PR #5876:
URL: https://github.com/apache/datafusion-comet/pull/5876#discussion_r3998842774
##########
pom.xml:
##########
@@ -859,29 +859,85 @@ under the License.
</pluginManagement>
</build>
</profile>
+ <!--
+ Compile Scala with warnings promoted to errors. Not active by default;
run it
+ explicitly, e.g. `./mvnw test-compile -Pspark-3.5 -Pstrict-warnings`.
+
+ This passes on the Scala 2.12 profiles. The 2.13 profiles (spark-4.0 and
later)
+ still report warnings that 2.12 does not raise at all, dominated by
+ `-Xlint:nonlocal-return` (a `return` inside a closure, which the compiler
+ implements by throwing) and non-exhaustive matches. Clearing those means
+ restructuring control flow rather than annotating it, so they are left
for a
+ follow-up rather than silenced here.
+
+ `args` is configured per execution rather than on the plugin, because
main and
+ test sources warrant different flags (see `-Ywarn-value-discard` below).
An
+ execution's `args` replaces the plugin-level list instead of appending
to it, so
+ each list below is self-contained.
+
+ Two lints are deliberately absent from both lists:
+
+ `-Ywarn-unused:params` reports ~90-120 parameters per profile, and
essentially
+ all of them are structurally unfixable rather than dead: `Native.scala`
is 64
+ `@native` declarations whose parameters have no body to be used in, and
the rest
+ are cross-version shims under `src/main/spark-3.x`, `spark-4.x` and
friends that
+ take a parameter to satisfy the signature of the Spark version they
shim. Nor can
+ those be annotated away one by one: the set differs between Scala 2.12
and 2.13
+ (`CometScanContrib.scala` warns under spark-3.5 but not spark-4.0, and
vice versa
+ for `ShimSparkErrorConverter.scala`), so any `@nowarn` that silences one
profile
+ is an unused annotation on the other, which `-Xlint:_` then reports via
+ `-Xlint:nowarn` and `-Xfatal-warnings` turns into a build failure.
+
+ `-Ywarn-value-discard` stays on for main sources, where a discarded
result is
+ usually a dropped builder or a swallowed return, but is off for test
sources.
+ Under it a ScalaTest suite reports ~1,250-1,450 warnings, and the two
largest
+ groups are the idiom itself: an `assert(...)` in trailing position
discards an
+ `org.scalatest.Assertion`, and `checkSparkAnswerAndOperator` discards the
+ `(SparkPlan, SparkPlan)` it returns at all but 30 of its ~1,300 call
sites.
+ -->
<profile>
- <id>strict-warnings</id>
- <build>
- <plugins>
- <plugin>
- <groupId>net.alchim31.maven</groupId>
- <artifactId>scala-maven-plugin</artifactId>
- <configuration>
- <args>
- <arg>-deprecation</arg>
- <arg>-unchecked</arg>
- <arg>-feature</arg>
- <arg>-Xlint:_</arg>
- <arg>-Ywarn-dead-code</arg>
- <arg>-Ywarn-numeric-widen</arg>
- <arg>-Ywarn-value-discard</arg>
-
<arg>-Ywarn-unused:imports,patvars,privates,locals,params,-implicits</arg>
- <arg>-Xfatal-warnings</arg>
- </args>
- </configuration>
- </plugin>
- </plugins>
- </build>
+ <id>strict-warnings</id>
+ <build>
+ <plugins>
+ <plugin>
+ <groupId>net.alchim31.maven</groupId>
+ <artifactId>scala-maven-plugin</artifactId>
+ <executions>
+ <execution>
+ <id>scala-compile-first</id>
+ <configuration>
+ <args>
+ <arg>-deprecation</arg>
+ <arg>-unchecked</arg>
+ <arg>-feature</arg>
+ <arg>-Xlint:_</arg>
+ <arg>-Ywarn-dead-code</arg>
+ <arg>-Ywarn-numeric-widen</arg>
+ <arg>-Ywarn-value-discard</arg>
+
<arg>-Ywarn-unused:imports,patvars,privates,locals,-implicits</arg>
Review Comment:
Thanks for the `-Wconf` pointer. I tried it rather than guessing, and on
Scala 2.12.18 it works the way you expected:
```
-Wconf:cat=unused-params&site=org\.apache\.comet\.Native\..*:s,cat=unused-params&src=.*/src/[a-z]+/spark-[^/]+/.*:s
```
Those two filters silence `Native` and every shim source, which is 96 of the
163 unused-parameter warnings on `-Pspark-3.5`. The other 67 are in shared
sources, though, so turning `params` back on with just these filters still
fails the build:
- **27 in main:** 4 are on private methods and can simply be removed. The
other 23 are on public extension points and serde helpers where the parameter
is part of the signature: overridable defaults like `getSupportLevel` and
`CometScanContrib.tryTransformV1`, and helpers like `createBinaryExpr(expr, …)`
(13 callers).
- **40 in tests:** 4 are genuinely unused and can be removed. The other 36
are in fixtures with fixed signatures, almost all of them fakes of Celeborn's
client API.
I can see two ways forward and would like your preference before changing
anything:
**A.** Keep `params` out of the profile, as the PR does now.
**B.** Turn `params` back on with the `Native` and shim filters, remove the
8 unused parameters, and add per-method `-Wconf` site filters for the remaining
59. New code keeps the check, but the POM carries a longer filter list that has
to be updated whenever a signature like that is added.
For this PR I'd lean towards A, plus a follow-up issue for B. That follow-up
could also drop the unused `expr` parameter from the serde helpers, which is an
API change I didn't want to fold in here. If you'd rather have B land now, I'm
happy to do it. Which do you prefer?
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