After upgrade to 2.0.1 Gradle is no longer finding generated sources

[tanadeau]

Describe the bug

Exact same annotation processors, Gradle version, etc. works with 1.13.7.Final; however, on upgrade to 2.0.0.Final or 2.0.1.Final, I get hundreds of errors caused by not finding generated classes.

Expected behavior

All sources in build/generated/sources/annotationProcessor/java/main are seen during compilation.

Actual behavior

Sources in directory above are not found creating many cannot find symbol errors.

To Reproduce

I need to create a reproducer with a much smaller annotation processor library.

Steps to reproduce the behavior:
1.
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Configuration

# Add your application.properties here, if applicable.

Screenshots

(If applicable, add screenshots to help explain your problem.)

Environment (please complete the following information):

Output of uname -a or ver

Darwin C02YK01PLVCG-ML 20.5.0 Darwin Kernel Version 20.5.0: Sat May  8 05:10:33 PDT 2021; root:xnu-7195.121.3~9/RELEASE_X86_64 x86_64

Output of java -version

openjdk 11.0.11 2021-04-20
OpenJDK Runtime Environment AdoptOpenJDK-11.0.11+9 (build 11.0.11+9)
OpenJDK 64-Bit Server VM AdoptOpenJDK-11.0.11+9 (build 11.0.11+9, mixed mode)

GraalVM version (if different from Java)

Quarkus version or git rev

2.0.1.Final

Build tool (ie. output of mvnw --version or gradlew --version)

------------------------------------------------------------
Gradle 7.1.1
------------------------------------------------------------

Build time:   2021-07-02 12:16:43 UTC
Revision:     774525a055494e0ece39f522ac7ad17498ce032c

Kotlin:       1.4.31
Groovy:       3.0.7
Ant:          Apache Ant(TM) version 1.10.9 compiled on September 27 2020
JVM:          11.0.11 (AdoptOpenJDK 11.0.11+9)
OS:           Mac OS X 11.4 x86_64

Additional context

(Add any other context about the problem here.)

[quarkus-bot]

/cc @evanchooly, @glefloch, @quarkusio/devtools

[tanadeau]

I have a feeling it may be related to d8fd0b9

[glefloch]

Thanks for reporting this @tanadeau.

I generated a sample project from code.quarkus.io with kotlin and grpc extension.
I'm not able to reproduce this error. I tried with both gradle 6.9 and 7.1.1. Could you share a reproducer?

[tanadeau]

Thanks for taking a look. We're using our own annotation processors so I think it may be the fact that they are not in an extension. I'll see if I can make a small reproducer.

[tanadeau]

I found the issue. This is related to #18569. We have a "-Werror" passed to javac, and the warnings coming from microprofile-config-api were causing the compilation round to fail before the generated sources were processed.