filemanager option handling and -Xlint:path

[Jonathan Gibbons]

I consider this a minor P4-level bug.  We're (still) teasing apart the 
use of the JavacFileManager as a standalone file manager from the 
mainline javac option decoding.   I'm (slightly) surprised at your 
example: I was expecting an example in which -Xlint:path comes *after* 
the -classpath option, for which there is definitely no attempt to 
handle it.

In general, I think API clients should be using API methods in 
preference to handleOption, and I think API clients have greater 
opportunity to check paths for validity before using setLocation. If 
anything, I'd prefer to either add API to enable warnings, or at least 
ensure that fm.handleOption("-Xlint:path") works on paths set via 
setLocation.

As for user file managers, it is currently up to them what options they 
support.  We have work in progress to at least define what options the 
file manager are provided by the default JDK ToolProvider's 
getSystemJavaCompiler.getStandardFileManager.  The main problem is what 
package/class to define this on. One likely possibility coming up is the 
javadoc on the jdk.compiler module itself.

-- Jon


On 10/24/16 9:12 AM, Liam Miller-Cushon wrote:
> -Xlint:path doesn't work when javac is invoked using JSR 199.
>
> The CLI breaks a circular dependency between option handling and 
> filemanager initialization, but JSR 199 eagerly initializes the 
> filemanager before xlint options have been processed.
>
> Do you consider this to be a bug? I'm not sure what should happen for 
> user-supplied filemanagers, but the example below seems fixable:
>
> === JavacToolDemo.java ===
> import javax.tools.JavaCompiler;
> import javax.tools.StandardJavaFileManager;
> import javax.tools.ToolProvider;
> import java.util.Arrays;
>
> public class JavacToolDemo {
>   public static void main(String[] args) {
>     JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
>     StandardJavaFileManager fileManager = 
> compiler.getStandardFileManager(null, null, null);
>     JavaCompiler.CompilationTask task =
>       compiler.getTask(
>           null,
>           null,
>           null,
>           Arrays.asList("-verbose", "-Xlint:path,unchecked", "-cp", 
> "lib.jar"),
>           null,
>           fileManager.getJavaFileObjects("Hello.java"));
>     System.exit(task.call() ? 0 : 1);
>   }
> }
> ===
>
> The javac CLI handles -Xlint correctly:
>
> $ echo "class Hello { java.util.List xs; }" > Hello.java
> $ echo "Class-Path: NoSuch.jar" > Manifest.txt
> $ jar cfm lib.jar Manifest.txt
> $ javac -verbose -Xlint:all -cp lib.jar Hello.java
> ...
> [search path for class files: ... NoSuch.jar]
> ...
> warning: [path] bad path element "NoSuch.jar": no such file or directory
> Hello.java:1: warning: [rawtypes] found raw type: List
>
> The API does not:
>
> $ javac JavacToolDemo.java
> $ java JavacToolDemo
> ...
> [search path for class files: ... NoSuch.jar]
> ...
> Hello.java:1: warning: [rawtypes] found raw type: List