Re: Package, import and type declarations are allowed now in module-info.java by spec

[Alex Buckley]

Imagine the 7.6 text about the host system wasn't there. Now the JLS has 
no rules about the name of the file from which a CompilationUnit 
production is parsed. A compiler is therefore allowed to reject a file 
named module-info.java whenever it wishes.


Now imagine the 7.6 text is put back. Since it allows the host system to 
choose when to follow it, it has no bearing on the previous paragraph.


Georgiy, I don't think it's productive to continue this thread further.

Alex

On 3/21/2016 6:44 AM, Georgiy Rakov wrote:

According to my understanding import or type declarations are
*optionally* followed by a type declaration according to the
CompilationUnit grammar rule. JLS 7.6 just conditionally allows compiler
to restrict file names to be aligned with type declaration but the
compile errors are produced even if the condition is not met.

Thanks,
Georgiy.

On 10.03.2016 1:02, Alex Buckley wrote:

The JLS doesn't prevent javac from rejecting a package declaration or
an import declaration in a file called module-info.java.

In fact, since a package declaration or import declaration must be
followed by a type declaration, and since a type declaration cannot
use a hyphen, javac is free to take the optional rule from JLS 7.6 --
filename must align with type declaration -- and develop it further:
rejecting a package declaration or import declaration in
module-info.java because the filename cannot possibly align with any
type declaration.

I can't speak to what a particular EA build of javac is doing with a
particular option. javac options are irrelevant to the JLS. If a
compiler accepts the Java language circa SE 9, then a module
declaration is a valid compilation unit. What's the name of the file
containing such a compilation unit? Anything the compiler likes.

Alex

On 3/9/2016 5:14 AM, Georgiy Rakov wrote:

Hi Alex,

if I understand correctly you mean about following assertions from
JLS 7.6:

If and only if packages are stored in a file system (§7.2
),
the host system may choose to enforce the restriction that it is a
compile-time error if a type is not found in a file under a name
composed of the type name plus an extension (such as |.java|or
|.jav|) if either of the following is true:

  *

The type is referred to by code in other compilation units of
the package in which the type is declared.

  *

The type is declared |public|(and therefore is potentially
accessible from code in other packages).

Literally these assertion doesn't make presented behavior corresponding
to spec because the declared type is neither public nor being referred
to from other sources being compiled.

Nevertheless following sources doesn't compile either despite the fact
that no types are declared there at all.
Namely when only package is specified:

mod\module-info.java:
module mod {
 exports pkg;
}

mod\pkg\module-info.java:
package pkg;

then compiling it by following command line with javac from [2]:

javac -modulesourcepath . mod\module-info.java
mod\pkg\module-info.java

causes following output:

mod\pkg\module-info.java:1: error: expected 'module
package pkg;
^
1 error

When only import statment is specified:

mod\module-info.java:
module mod {
 exports pkg;
}

mod\pkg\module-info.java:
import java.util.List;

then compiling it by following command line with javac from [2]:

javac -modulesourcepath . mod\module-info.java
mod\pkg\module-info.java

causes following output:

mod\pkg\module-info.java:1: error: expected 'module'
import java.util.List;
^
1 error

Please see minimized test cases attached in tests23.zip. In order to
reproduce, please:

1. Unzip the attached archive to some dir on Windows machined, say
directory A;
2. Rename A\test2\test_bat to A\test2\test.bat and A\test3\test_bat to
A\test3\test.bat;
3. Modify these two test.bat files by changing JDK_HOME variable to
point to your jigsaw JDK 9 installation directory;
4. Run test.bat files in turn.

BTW: javac behavior [2] currently differs depending on whether sources
are compiled "in module" mode or not. By "module mode" I mean specifying
modulesourcepath option. For instance without modulesourcepath option
module declarations are not recognized as valid grammar while import
declarations contained within module-info.java compile successfully.
This can be seen by experimenting with test3 from the attached
testcases. Now javac from [2] even can throw exception in "non-module"
mode, please see https://bugs.openjdk.java.net/browse/JDK-8150733.

Could you please tell if spec will specify somehow two modes of
processing java-sources, now it [1] doesn't.

[1] http://cr.openjdk.java.net/~mr/jigsaw/spec/lang-vm.html
[2]
http://download.java.net/java/jigsaw/archive/106/binaries/jigsaw-jdk-9-ea+106_windows-x86_bin.zip


Thanks,
Georgiy.

On 26.02.2016 

Re: Package, import and type declarations are allowed now in module-info.java by spec

[Georgiy Rakov]

According to my understanding import or type declarations are 
*optionally* followed by a type declaration according to the 
CompilationUnit grammar rule. JLS 7.6 just conditionally allows compiler 
to restrict file names to be aligned with type declaration but the 
compile errors are produced even if the condition is not met.


Thanks,
Georgiy.

On 10.03.2016 1:02, Alex Buckley wrote:
The JLS doesn't prevent javac from rejecting a package declaration or 
an import declaration in a file called module-info.java.


In fact, since a package declaration or import declaration must be 
followed by a type declaration, and since a type declaration cannot 
use a hyphen, javac is free to take the optional rule from JLS 7.6 -- 
filename must align with type declaration -- and develop it further: 
rejecting a package declaration or import declaration in 
module-info.java because the filename cannot possibly align with any 
type declaration.


I can't speak to what a particular EA build of javac is doing with a 
particular option. javac options are irrelevant to the JLS. If a 
compiler accepts the Java language circa SE 9, then a module 
declaration is a valid compilation unit. What's the name of the file 
containing such a compilation unit? Anything the compiler likes.


Alex

On 3/9/2016 5:14 AM, Georgiy Rakov wrote:

Hi Alex,

if I understand correctly you mean about following assertions from 
JLS 7.6:


If and only if packages are stored in a file system (§7.2
),
the host system may choose to enforce the restriction that it is a
compile-time error if a type is not found in a file under a name
composed of the type name plus an extension (such as |.java|or
|.jav|) if either of the following is true:

  *

The type is referred to by code in other compilation units of
the package in which the type is declared.

  *

The type is declared |public|(and therefore is potentially
accessible from code in other packages).

Literally these assertion doesn't make presented behavior corresponding
to spec because the declared type is neither public nor being referred
to from other sources being compiled.

Nevertheless following sources doesn't compile either despite the fact
that no types are declared there at all.
Namely when only package is specified:

mod\module-info.java:
module mod {
 exports pkg;
}

mod\pkg\module-info.java:
package pkg;

then compiling it by following command line with javac from [2]:

javac -modulesourcepath . mod\module-info.java 
mod\pkg\module-info.java


causes following output:

mod\pkg\module-info.java:1: error: expected 'module
package pkg;
^
1 error

When only import statment is specified:

mod\module-info.java:
module mod {
 exports pkg;
}

mod\pkg\module-info.java:
import java.util.List;

then compiling it by following command line with javac from [2]:

javac -modulesourcepath . mod\module-info.java 
mod\pkg\module-info.java


causes following output:

mod\pkg\module-info.java:1: error: expected 'module'
import java.util.List;
^
1 error

Please see minimized test cases attached in tests23.zip. In order to
reproduce, please:

1. Unzip the attached archive to some dir on Windows machined, say
directory A;
2. Rename A\test2\test_bat to A\test2\test.bat and A\test3\test_bat to
A\test3\test.bat;
3. Modify these two test.bat files by changing JDK_HOME variable to
point to your jigsaw JDK 9 installation directory;
4. Run test.bat files in turn.

BTW: javac behavior [2] currently differs depending on whether sources
are compiled "in module" mode or not. By "module mode" I mean specifying
modulesourcepath option. For instance without modulesourcepath option
module declarations are not recognized as valid grammar while import
declarations contained within module-info.java compile successfully.
This can be seen by experimenting with test3 from the attached
testcases. Now javac from [2] even can throw exception in "non-module"
mode, please see https://bugs.openjdk.java.net/browse/JDK-8150733.

Could you please tell if spec will specify somehow two modes of
processing java-sources, now it [1] doesn't.

[1] http://cr.openjdk.java.net/~mr/jigsaw/spec/lang-vm.html
[2]
http://download.java.net/java/jigsaw/archive/106/binaries/jigsaw-jdk-9-ea+106_windows-x86_bin.zip 



Thanks,
Georgiy.

On 26.02.2016 21:26, Alex Buckley wrote:

On 2/26/2016 8:37 AM, Georgiy Rakov wrote:

current spec [1] now contains following assertions related to grammar:

A compilation unit (JLS 7.3) may contain a module declaration, in
which case the filename of the compilation unit is typically
|module-info.java|.

CompilationUnit:
   [PackageDeclaration] {ImportDeclaration} {TypeDeclaration}
   ModuleDeclaration

These assertions allows to specify any of import, package or type
declarations in 

Re: Package, import and type declarations are allowed now in module-info.java by spec

[Paul Benedict]

I am happy to say the latest EA only allows "module" or types. It is
either-or but not both.

Cheers,
Paul

On Tue, Mar 15, 2016 at 12:43 PM, Paul Benedict 
wrote:

> On Mon, Mar 14, 2016 at 5:21 PM, Alex Buckley 
> wrote:
>
>> The JLS doesn't know what the string "module-info.class" means or what a
>> "JAR root" is.
>
>
> Of course. Though that wasn't my ultimate point; I was merely illustrating
> (philosophically) why having "package" in module-info.java is nonsensical
> syntax. A "package" statement doesn't mean anything useful in the context
> of specifying module configuration. As far as I am aware, the module syntax
> is meant to standalone in the file, but please correct me if you have other
> intentions for the syntax. If you can also declare types, then a "package"
> statement begins to make more sense -- but it would seem like a clumsy way
> of doing things, which I wouldn't advocate (or allow syntactically).
>
> Cheers,
> Paul
>
>
>> In 3/14/2016 9:08 AM, Paul Benedict wrote:
>>
>>> Alex, you wrote: "The JLS doesn't prevent javac from rejecting a package
>>> declaration or an import declaration in a file called module-info.java."
>>>
>>> It seems that a package declaration, in this context, should be
>>> prohibited syntax because module-info.class is always in the JAR root
>>> which has no package.
>>>
>>> Cheers,
>>> Paul
>>>
>>> On Wed, Mar 9, 2016 at 4:02 PM, Alex Buckley >> > wrote:
>>>
>>> The JLS doesn't prevent javac from rejecting a package declaration
>>> or an import declaration in a file called module-info.java.
>>>
>>> In fact, since a package declaration or import declaration must be
>>> followed by a type declaration, and since a type declaration cannot
>>> use a hyphen, javac is free to take the optional rule from JLS 7.6
>>> -- filename must align with type declaration -- and develop it
>>> further: rejecting a package declaration or import declaration in
>>> module-info.java because the filename cannot possibly align with any
>>> type declaration.
>>>
>>> I can't speak to what a particular EA build of javac is doing with a
>>> particular option. javac options are irrelevant to the JLS. If a
>>> compiler accepts the Java language circa SE 9, then a module
>>> declaration is a valid compilation unit. What's the name of the file
>>> containing such a compilation unit? Anything the compiler likes.
>>>
>>> Alex
>>>
>>> On 3/9/2016 5:14 AM, Georgiy Rakov wrote:
>>>
>>> Hi Alex,
>>>
>>> if I understand correctly you mean about following assertions
>>> from JLS 7.6:
>>>
>>>  If and only if packages are stored in a file system (§7.2
>>>
>>> <
>>> http://docs.oracle.com/javase/specs/jls/se8/html/jls-7.html#jls-7.2>),
>>>  the host system may choose to enforce the restriction that
>>> it is a
>>>  compile-time error if a type is not found in a file under a
>>> name
>>>  composed of the type name plus an extension (such as
>>> |.java|or
>>>  |.jav|) if either of the following is true:
>>>
>>>*
>>>
>>>  The type is referred to by code in other compilation
>>> units of
>>>  the package in which the type is declared.
>>>
>>>*
>>>
>>>  The type is declared |public|(and therefore is
>>> potentially
>>>  accessible from code in other packages).
>>>
>>> Literally these assertion doesn't make presented behavior
>>> corresponding
>>> to spec because the declared type is neither public nor being
>>> referred
>>> to from other sources being compiled.
>>>
>>> Nevertheless following sources doesn't compile either despite
>>> the fact
>>> that no types are declared there at all.
>>> Namely when only package is specified:
>>>
>>>  mod\module-info.java:
>>>  module mod {
>>>   exports pkg;
>>>  }
>>>
>>>  mod\pkg\module-info.java:
>>>  package pkg;
>>>
>>> then compiling it by following command line with javac from [2]:
>>>
>>>  javac -modulesourcepath . mod\module-info.java
>>> mod\pkg\module-info.java
>>>
>>> causes following output:
>>>
>>>  mod\pkg\module-info.java:1: error: expected 'module
>>>  package pkg;
>>>  ^
>>>  1 error
>>>
>>> When only import statment is specified:
>>>
>>>  mod\module-info.java:
>>>  module mod {
>>>   exports pkg;
>>>  }
>>>
>>>  mod\pkg\module-info.java:
>>>  import java.util.List;
>>>
>>> then compiling it by following command line with javac from [2]:
>>>
>>>  javac 

Re: Package, import and type declarations are allowed now in module-info.java by spec

[Paul Benedict]

On Mon, Mar 14, 2016 at 5:21 PM, Alex Buckley 
wrote:

> The JLS doesn't know what the string "module-info.class" means or what a
> "JAR root" is.


Of course. Though that wasn't my ultimate point; I was merely illustrating
(philosophically) why having "package" in module-info.java is nonsensical
syntax. A "package" statement doesn't mean anything useful in the context
of specifying module configuration. As far as I am aware, the module syntax
is meant to standalone in the file, but please correct me if you have other
intentions for the syntax. If you can also declare types, then a "package"
statement begins to make more sense -- but it would seem like a clumsy way
of doing things, which I wouldn't advocate (or allow syntactically).

Cheers,
Paul


> In 3/14/2016 9:08 AM, Paul Benedict wrote:
>
>> Alex, you wrote: "The JLS doesn't prevent javac from rejecting a package
>> declaration or an import declaration in a file called module-info.java."
>>
>> It seems that a package declaration, in this context, should be
>> prohibited syntax because module-info.class is always in the JAR root
>> which has no package.
>>
>> Cheers,
>> Paul
>>
>> On Wed, Mar 9, 2016 at 4:02 PM, Alex Buckley > > wrote:
>>
>> The JLS doesn't prevent javac from rejecting a package declaration
>> or an import declaration in a file called module-info.java.
>>
>> In fact, since a package declaration or import declaration must be
>> followed by a type declaration, and since a type declaration cannot
>> use a hyphen, javac is free to take the optional rule from JLS 7.6
>> -- filename must align with type declaration -- and develop it
>> further: rejecting a package declaration or import declaration in
>> module-info.java because the filename cannot possibly align with any
>> type declaration.
>>
>> I can't speak to what a particular EA build of javac is doing with a
>> particular option. javac options are irrelevant to the JLS. If a
>> compiler accepts the Java language circa SE 9, then a module
>> declaration is a valid compilation unit. What's the name of the file
>> containing such a compilation unit? Anything the compiler likes.
>>
>> Alex
>>
>> On 3/9/2016 5:14 AM, Georgiy Rakov wrote:
>>
>> Hi Alex,
>>
>> if I understand correctly you mean about following assertions
>> from JLS 7.6:
>>
>>  If and only if packages are stored in a file system (§7.2
>>
>> <
>> http://docs.oracle.com/javase/specs/jls/se8/html/jls-7.html#jls-7.2>),
>>  the host system may choose to enforce the restriction that
>> it is a
>>  compile-time error if a type is not found in a file under a
>> name
>>  composed of the type name plus an extension (such as
>> |.java|or
>>  |.jav|) if either of the following is true:
>>
>>*
>>
>>  The type is referred to by code in other compilation
>> units of
>>  the package in which the type is declared.
>>
>>*
>>
>>  The type is declared |public|(and therefore is
>> potentially
>>  accessible from code in other packages).
>>
>> Literally these assertion doesn't make presented behavior
>> corresponding
>> to spec because the declared type is neither public nor being
>> referred
>> to from other sources being compiled.
>>
>> Nevertheless following sources doesn't compile either despite
>> the fact
>> that no types are declared there at all.
>> Namely when only package is specified:
>>
>>  mod\module-info.java:
>>  module mod {
>>   exports pkg;
>>  }
>>
>>  mod\pkg\module-info.java:
>>  package pkg;
>>
>> then compiling it by following command line with javac from [2]:
>>
>>  javac -modulesourcepath . mod\module-info.java
>> mod\pkg\module-info.java
>>
>> causes following output:
>>
>>  mod\pkg\module-info.java:1: error: expected 'module
>>  package pkg;
>>  ^
>>  1 error
>>
>> When only import statment is specified:
>>
>>  mod\module-info.java:
>>  module mod {
>>   exports pkg;
>>  }
>>
>>  mod\pkg\module-info.java:
>>  import java.util.List;
>>
>> then compiling it by following command line with javac from [2]:
>>
>>  javac -modulesourcepath . mod\module-info.java
>> mod\pkg\module-info.java
>>
>> causes following output:
>>
>>  mod\pkg\module-info.java:1: error: expected 'module'
>>  import java.util.List;
>>  ^
>>  1 error
>>
>> Please see minimized test cases attached in 

Re: Package, import and type declarations are allowed now in module-info.java by spec

[Alex Buckley]

The JLS doesn't know what the string "module-info.class" means or what a 
"JAR root" is. It only knows about Unicode input matching the 
CompilationUnit production. Nothing is mandated about the filesystem 
layout of files containing CompilationUnit productions that include a 
PackageDeclaration. For clarity, we could extend 7.6's compiler guidance 
to cover a file called module-info.java, but technically the guidance is 
already broad enough to allow a compiler to "do the right thing".


Alex

On 3/14/2016 9:08 AM, Paul Benedict wrote:

Alex, you wrote: "The JLS doesn't prevent javac from rejecting a package
declaration or an import declaration in a file called module-info.java."

It seems that a package declaration, in this context, should be
prohibited syntax because module-info.class is always in the JAR root
which has no package.

Cheers,
Paul

On Wed, Mar 9, 2016 at 4:02 PM, Alex Buckley > wrote:

The JLS doesn't prevent javac from rejecting a package declaration
or an import declaration in a file called module-info.java.

In fact, since a package declaration or import declaration must be
followed by a type declaration, and since a type declaration cannot
use a hyphen, javac is free to take the optional rule from JLS 7.6
-- filename must align with type declaration -- and develop it
further: rejecting a package declaration or import declaration in
module-info.java because the filename cannot possibly align with any
type declaration.

I can't speak to what a particular EA build of javac is doing with a
particular option. javac options are irrelevant to the JLS. If a
compiler accepts the Java language circa SE 9, then a module
declaration is a valid compilation unit. What's the name of the file
containing such a compilation unit? Anything the compiler likes.

Alex

On 3/9/2016 5:14 AM, Georgiy Rakov wrote:

Hi Alex,

if I understand correctly you mean about following assertions
from JLS 7.6:

 If and only if packages are stored in a file system (§7.2

),
 the host system may choose to enforce the restriction that
it is a
 compile-time error if a type is not found in a file under a
name
 composed of the type name plus an extension (such as |.java|or
 |.jav|) if either of the following is true:

   *

 The type is referred to by code in other compilation
units of
 the package in which the type is declared.

   *

 The type is declared |public|(and therefore is potentially
 accessible from code in other packages).

Literally these assertion doesn't make presented behavior
corresponding
to spec because the declared type is neither public nor being
referred
to from other sources being compiled.

Nevertheless following sources doesn't compile either despite
the fact
that no types are declared there at all.
Namely when only package is specified:

 mod\module-info.java:
 module mod {
  exports pkg;
 }

 mod\pkg\module-info.java:
 package pkg;

then compiling it by following command line with javac from [2]:

 javac -modulesourcepath . mod\module-info.java
mod\pkg\module-info.java

causes following output:

 mod\pkg\module-info.java:1: error: expected 'module
 package pkg;
 ^
 1 error

When only import statment is specified:

 mod\module-info.java:
 module mod {
  exports pkg;
 }

 mod\pkg\module-info.java:
 import java.util.List;

then compiling it by following command line with javac from [2]:

 javac -modulesourcepath . mod\module-info.java
mod\pkg\module-info.java

causes following output:

 mod\pkg\module-info.java:1: error: expected 'module'
 import java.util.List;
 ^
 1 error

Please see minimized test cases attached in tests23.zip. In order to
reproduce, please:

1. Unzip the attached archive to some dir on Windows machined, say
directory A;
2. Rename A\test2\test_bat to A\test2\test.bat and
A\test3\test_bat to
A\test3\test.bat;
3. Modify these two test.bat files by changing JDK_HOME variable to
point to your jigsaw JDK 9 installation directory;
4. Run test.bat files in turn.

BTW: javac behavior [2] currently differs depending on whether
sources
are compiled "in module" mode or not. By "module mode" I mean

Re: Package, import and type declarations are allowed now in module-info.java by spec

[Alex Buckley]

On 2/26/2016 8:37 AM, Georgiy Rakov wrote:

current spec [1] now contains following assertions related to grammar:

A compilation unit (JLS 7.3) may contain a module declaration, in
which case the filename of the compilation unit is typically
|module-info.java|.

CompilationUnit:
   [PackageDeclaration] {ImportDeclaration} {TypeDeclaration}
   ModuleDeclaration

These assertions allows to specify any of import, package or type
declarations in any compilation unit, for instance module-info.java is
allowed to contain any of the mentioned declarations. However currently
javac in the latest jigsaw build [2] reports an error on such cases
provided they are compiled in module mode. For example if we have
following directory structure:

mod\module-info.java:
module mod {
 exports pkg;
}

mod\pkg\module-info.java:
package pkg;

class C {
}

then compiling it by following command line with javac from [2]:

javac -modulesourcepath . mod\module-info.java mod\pkg\module-info.java

causes following output:

mod\pkg\module-info.java:1: error: expected 'module'
package pkg;
^
1 error


javac is merely choosing to implement the rule at the end of JLS 7.6 
that a type declaration (optionally preceded by package/import 
declarations) must be provided in a suitably named file.


Perhaps I should say "a variant of the rule" because 7.6 as written 
concerns a public type and your example has a package-access type. 
Still, bottom line, javac is free to require that a compilation unit 
which starts with a package declaration _must not_ be in a file called 
foo-bar.java -- the hyphen indicates a name that can't possibly align 
with the type declared in the compilation unit.


The error message for mod\pkg\module-info.java could be a bit more 
helpful, but that's a quality-of-implementation detail.


Conversely, a compilation unit that contains a module declaration _may_ 
be in a file called module-info.java, or in a file called foo-bar.java, 
or in a file called mod_decl.JAV. The "typically" in [1] is meant to 
indicate that the sub-clause on filename is non-normative. This is akin 
to how a compilation unit that contains a package-access type 
declaration for class C _may_ be in a file D.java.


Alex

Package, import and type declarations are allowed now in module-info.java by spec

[Georgiy Rakov]

Hello,

current spec [1] now contains following assertions related to grammar:

   A compilation unit (JLS 7.3) may contain a module declaration, in
   which case the filename of the compilation unit is typically
   |module-info.java|.

   CompilationUnit:
  [PackageDeclaration] {ImportDeclaration} {TypeDeclaration}
  ModuleDeclaration

These assertions allows to specify any of import, package or type 
declarations in any compilation unit, for instance module-info.java is 
allowed to contain any of the mentioned declarations. However currently 
javac in the latest jigsaw build [2] reports an error on such cases 
provided they are compiled in module mode. For example if we have 
following directory structure:


   mod\module-info.java:
   module mod {
exports pkg;
   }

   mod\pkg\module-info.java:
   package pkg;

   class C {
   }

then compiling it by following command line with javac from [2]:

   javac -modulesourcepath . mod\module-info.java mod\pkg\module-info.java

causes following output:

   mod\pkg\module-info.java:1: error: expected 'module'
   package pkg;
   ^
   1 error

The minimized testcase is attached; in order to run it please:

1. Unzip the attached archive to some dir on Windows machined, say 
directory A;

2. Rename A\test\test_bat to A\test\test.bat;
3. Modify test.bat by changing JDK_HOME variable to point to your jigsaw 
JDK 9 installation directory;

4. Run test.bat.

It seems to me either spec or implementation issue, could you please 
tell if you agree.


[1] http://cr.openjdk.java.net/~mr/jigsaw/spec/lang-vm.html
[2] 
http://download.java.net/java/jigsaw/archive/106/binaries/jigsaw-jdk-9-ea+106_windows-x86_bin.zip


Thanks,
Georgiy.