refactor: replace deprecated extends App with explicit main method#1131
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build issues
[error] -- [E039] Reference Error: /home/runner/work/pekko-http/pekko-http/http2-tests/src/test/scala/org/apache/pekko/http/scaladsl/Http2ServerTest.scala:58:96
[error] 58 | case HttpRequest(GET, Uri.Path("/image-page"), _, _, _) => imagePage
[error] | ^^^^^^^^^
[error] |forward reference to imagePage (defined on line 135) extends over the definition of syncHandler (on line 55)
[error] |
[error] | longer explanation available when compiling with `-explain`
[error] one error found
[127.671s][info][gc] GC(88) Pause Young (Normal) (G1 Evacuation Pause) 2317M->1503M(2902M) 135.420ms
[error] -- [E039] Reference Error: /home/runner/work/pekko-http/pekko-http/http-tests/src/test/scala/org/apache/pekko/http/scaladsl/server/TestServer.scala:69:21
[error] 69 | complete(index)
[error] | ^^^^^
[error] |forward reference to index (defined on line 119) extends over the definition of routes (on line 62)
[error] |
[error] | longer explanation available when compiling with `-explain`
[error] one error found
[error] (http2-tests / Test / compileIncremental) Compilation failed
[error] (http-tests / Test / compileIncremental) Compilation failed
[error] Total time: 116 s (0:01:56.0), completed 2026 Jul 6 06:41:18
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Motivation: Moving lazy vals from object-level members into def main() body introduced forward reference compilation errors since local vals cannot reference later definitions in the same block. Modification: Move lazy val index/imagePage and def imagesBlock definitions before the code that references them (syncHandler/routes). Result: No more forward reference compilation errors. Tests: sbt "http2-tests / Test / compile" "http-tests / Test / compile" - success References: Fixes CI failures in PR apache#1131
Motivation:
`extends App` is deprecated in Scala 3. Replace with explicit `def main`
method for forward compatibility.
Modification:
Replace `object X extends App { ... }` with
`object X { def main(args: Array[String]): Unit = { ... } }`
in 14 test and example files.
Result:
No more usage of deprecated `scala.App` trait. Code is compatible with Scala 3.
Tests:
Not run - docs only
References:
None - Scala 3 compatibility
Motivation: Moving lazy vals from object-level members into def main() body introduced forward reference compilation errors since local vals cannot reference later definitions in the same block. Modification: Move lazy val index/imagePage and def imagesBlock definitions before the code that references them (syncHandler/routes). Result: No more forward reference compilation errors. Tests: sbt "http2-tests / Test / compile" "http-tests / Test / compile" - success References: Fixes CI failures in PR apache#1131
Motivation: PR 1131 replaces deprecated Scala extends App usage with explicit main methods, but moving Http2ClientApp logic into main turned the singleRequest helper into a local method used before its definition. Modification: Move singleRequest back to object scope as a private helper while keeping the explicit main method. Result: Http2ClientApp keeps the PR's explicit main entry point and compiles without the local forward reference error. Tests: - rtk sbt "++2.13.18!" "docs / Test / compile" - passed - rtk sbt "++3.3.8!" "docs / Test / compile" - passed - rtk sbt "++3.8.4!" "docs / Test / compile" - passed - rtk scalafmt --mode diff-ref=origin/main - passed - rtk scalafmt --list --mode diff-ref=origin/main - passed - rtk git diff --check - passed - rtk sbt "docs / Test / headerCheck" - passed References: Refs apache#1131
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Motivation
extends Appis deprecated in Scala 3. Replace with explicitdef main(args: Array[String]): Unitmethod for forward compatibility.Modification
Replace
object X extends App { ... }withobject X { def main(args: Array[String]): Unit = { ... } }in doc example and test files.Result
No more usage of deprecated
scala.Apptrait. Code is compatible with Scala 3.Tests
Not run - docs only
References
None - Scala 3 compatibility