Quarkus: Quarkus master / dev mode / --enable-preview - compilation fails after .java file edit

[rsvoboda]

Quarkus master / dev mode / --enable-preview - compilation fails after .java file edit

https://github.com/quarkusio/quarkus/pull/8279 should make dev mode ready to work with --enable-preview flag, but I'm struggling with it. Tried on Java 14 and Java 15ea and Quarkus master 079cf3925c

I can run dev mode, simple rest endpoint provides the content, it blows up when the simple jaxrs resource is edited, compilation fails, java.lang.RuntimeException: Compilation failed[error: --enable-preview must be used with either -source or --release] is returned by the endpoint.

Reproducer:

git clone https://github.com/rsvoboda/quarkus-jdk15.git
cd quarkus-jdk15
sdk use java 15.ea.21-open
mvn quarkus:dev
curl http://localhost:8080/hello    ## hello
edit ./src/main/java/io/quarkus/qe/jdk/Jdk15Resource.java
curl http://localhost:8080/hello    ## java.lang.RuntimeException: Compilation failed[error: --enable-preview must be used with either -source or --release]

[geoand]

@rsvoboda what does pom.xml looks like? Is it the pom.xml generated by our tooling?

[rsvoboda]

https://github.com/rsvoboda/quarkus-jdk15/blob/master/pom.xml

see reproducer steps in description ;)

[geoand]

I _think_ we don't handle maven.compiler.release at all.

[rsvoboda]

It's generated by Quarkus maven tooling ++ adjustments for maven.compiler.release and --enable-preview

[rsvoboda]

I think I tried release tag too, with the same result.

[geoand]

Could you give source and target a try as well? I am pretty sure those are handled properly

[rsvoboda]

I can confirm the same behavior for <release> tag.
Tried <source> and <target> tags too with the same failure.

[rsvoboda]

      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>${compiler-plugin.version}</version>
        <configuration>
          <source>15</source>
          <target>15</target>
          <compilerArgs>--enable-preview</compilerArgs>
        </configuration>
      </plugin>

[geoand]

OK, thanks for checking.

I'll take a look at this and get it fixed before 1.5.CR1 goes out.

[jaikiran]

Hello @rsvoboda, A temporary workaround (actually this is more than a workaround and in fact a better way) is to set the following properties in your pom.xml (which is what I did in your reproducer project) to get it working:

diff --git a/pom.xml b/pom.xml
index cecfb4f..6fbe8f9 100644
--- a/pom.xml
+++ b/pom.xml
@@ -8,7 +8,8 @@
   <properties>
     <compiler-plugin.version>3.8.1</compiler-plugin.version>
     <surefire-plugin.version>2.22.1</surefire-plugin.version>
-
+    <maven.compiler.source>15</maven.compiler.source>
+    <maven.compiler.target>15</maven.compiler.target>

I see that in your attempts to get this working you set the <source> and <target> to the Maven compiler plugin configuration (and not the Quarkus Maven plugin), hoping that it will work similar to what you did with the <compilerArgs> for the --enable-preview option. Looking at the code, the DevMojo can be enhanced to support this. So I went ahead and created a PR https://github.com/quarkusio/quarkus/pull/9245 to add this ability so that if any <source> and <target> are configured for the Maven compiler plugin, then they will get used (as a last resort) by the DevMojo. With that change in the PR, I was able to update your reproducer to just use:

diff --git a/pom.xml b/pom.xml
index cecfb4f..25a5cee 100644
--- a/pom.xml
+++ b/pom.xml
@@ -65,6 +65,8 @@
         <version>${compiler-plugin.version}</version>
         <configuration>
           <compilerArgs>--enable-preview</compilerArgs>
+          <source>15</source>
+          <target>15</target>
         </configuration>
       </plugin>

and have it working.