Prepare to make postfixOps syntax an error (not just a warning) unless the feature is explicitly enabled #6559

som-snytt · 2018-04-25T18:36:42Z

Require postfixOps opt-in instead of just warning.

som-snytt · 2018-04-26T04:06:38Z

After fixing gratuitous postfix in the compiler:

/var/folders/2_/xb149z895wb5f1y632xp2bw40000gq/T/sbt_19b03fbd/xsbt/Compat.scala:152: error: postfix operator headOption needs to be enabled
by making the implicit value scala.language.postfixOps visible.
This can be achieved by adding the import clause 'import scala.language.postfixOps'
or by setting the compiler option -language:postfixOps.
See the Scaladoc for value scala.language.postfixOps for a discussion
why the feature needs to be explicitly enabled.
          } headOption
            ^

Maybe @dwijnand knows if it's possible to set the scalac options for this compilation. It's ironic that the compatibility layer uses an incompatible feature.

dwijnand · 2018-04-26T05:58:35Z

Maybe @dwijnand knows if it's possible to set the scalac options for this compilation.

Nope, it's not configurable: https://github.com/sbt/zinc/blob/v1.1.5/internal/zinc-compile-core/src/main/scala/sbt/internal/inc/AnalyzingCompiler.scala#L350

It's ironic that the compatibility layer uses an incompatible feature.

Hardly fair: you're using the legacy 0.13 version of sbt. Not a problem in sbt 1: sbt/zinc@ecf121a#diff-569dc93f697b5a143e904e517b998e1dL124.

som-snytt · 2018-04-26T15:20:31Z

Thanks for checking, @dwijnand

I think the irony is still apt, since that class is for 2.9-2.11 compatibility but doesn't negotiate SIP 18; but it wouldn't be fair to stretch the point.

I'm not sure if scalac will upgrade to 1.1.x soon or if needing a 0.13.18 for 2.13 would be OK.

dwijnand · 2018-04-26T15:45:02Z

not sure if scalac will upgrade to 1.1.x soon

more reason to land #6256

if needing a 0.13.18 for 2.13 would be OK

quite probably not

sjrd · 2018-04-26T16:54:23Z

I'm not sure if scalac will upgrade to 1.1.x soon or if needing a 0.13.18 for 2.13 would be OK.

Even if scalac migrates to sbt 1.1.x, IIUC this change would still break users builds using sbt 0.13.x with Scala 2.13.0-M4+.

som-snytt · 2018-04-28T15:46:56Z

Yes, but if 0.13.18 is fixed, users can upgrade without much burden.

I'll look into whether a special dispensation is possible for sbt, which wouldn't be the first time.

adriaanm

I support this conceptually, but would like to structure the implementation differently.

first commit should just flip the bit on enableRequired
dispensation for sbt should go earlier in the pipeline, so we hit that path check only once
Ignore new warning in code base || Welcome to rebase central!

adriaanm · 2018-06-01T11:28:26Z

src/compiler/scala/tools/nsc/typechecker/Typers.scala

        val nestedOwners =
          featureTrait.owner.ownerChain.takeWhile(_ != languageFeatureModule.moduleClass).reverse
        val featureName = (nestedOwners map (_.name + ".")).mkString + featureTrait.name
        def action(): Boolean = {
          def hasImport = inferImplicitByType(featureTrait.tpe, context).isSuccess
          def hasOption = settings.language contains featureName
-          val OK = hasImport || hasOption
-          if (!OK) {
+          def dispensation = context.unit.source.file.path.endsWith("xsbt/Compat.scala")


I'm worried about doing this during type checking. I would be more comfortable with enabling the postfix ops feature from the start when creating a compiler run for this file.

Roger. Or you might say, "Rojair."

som-snytt · 2018-06-02T04:22:37Z

It works with local bootstrap, but no one has complained that feature warning can double-report because the explanatory part fools the reporter. (1 + must past twice through typer; the workaround is to cause the first feature warning with something benign like "hello, world" length.)

$ skalac -feature xsbt/Compat.scala
$ scalac -feature xsbt/Compat.scala
xsbt/Compat.scala:6: warning: postfix operator + should be enabled
by making the implicit value scala.language.postfixOps visible.
This can be achieved by adding the import clause 'import scala.language.postfixOps'
or by setting the compiler option -language:postfixOps.
See the Scaladoc for value scala.language.postfixOps for a discussion
why the feature should be explicitly enabled.
    List(1,2,3) map (1 +)
                       ^
xsbt/Compat.scala:6: warning: postfix operator + should be enabled
by making the implicit value scala.language.postfixOps visible.
    List(1,2,3) map (1 +)
                       ^
two warnings found

Usages unguarded by language import. In the same neighborhood, reduce infix as well.

adriaanm · 2018-06-04T12:10:49Z

Golden tickets need to be handed out before checking them more vigorously: the sbt opt-out commit should go before the "more opt-in" commit. Also please split commits into boyscouting and strictly core changes, especially when we're flipping bits.

Finally, kill your darlings, as William said (Faulkner, not the man in black): "Make postFixOps more opt-in" is a bit too clever.

som-snytt · 2018-06-04T13:59:52Z

This is branch order, but github shows date order. Maybe I broke something. The bit is flipped in its own commit, or do you mean you'd like the required test fixes to precede it?

Edit: reminder, don't forget to change title back to Post-postfix.

commit d91f4a4bfbd3a9b802ecebb9a9b6044c08eac0db (HEAD -> issue/post-postfix, origin/issue/post-postfix)
Author: Som Snytt <[email protected]>
Date:   Fri Jun 1 15:56:20 2018 -0700

    Make postfixOps more opt-in
    
    Require postfixOps feature opt-in instead of just warning.

commit fdcf987c246bb8db2cfc3f2db9a67cfdfe62128e
Author: Som Snytt <[email protected]>
Date:   Fri Jun 1 17:22:38 2018 -0700

    sbt gets a by

commit b3ca049600577a8227609e747868277708a28cd4
Author: Som Snytt <[email protected]>
Date:   Thu May 3 15:36:53 2018 -0700

    Reduce postfix ops in tests

commit b64946344b8b7b7171952a8beee649f84ac3f871
Author: Som Snytt <[email protected]>
Date:   Wed Apr 25 21:13:58 2018 -0700

    Reduce postfix ops
    
    Usages unguarded by language import. In the same
    neighborhood, reduce infix as well.

adriaanm · 2018-06-04T14:04:48Z

Ah, right! GH using date order is really unfortunate. Scabot just blindly follows it. I assume there's a rebase option to fix this?

For the boy scouting, I was referring to the boolean algebra wizardry in the bit flip commit. It's not a big deal, but in general it's just nicer for reviewing to separate behavior changes from cleanups. Both are appreciated, just better separate.

som-snytt · 2018-06-04T14:29:04Z

Note to self: t5675 is what rang a bell for the double-count issue for -feature over on #6635

dwijnand · 2018-06-04T15:23:34Z

I assume there's a rebase option to fix this?

I think it's possible to fix this with --committer-date-is-author-date.

If compiling exactly one file with a path ending in `xsbt/Compat.scala`, enable postfix ops. This avoids an error when sbt auto-compiles that file, after postfixOps feature is required. This commit does not attempt a general mechanism for adding hacks or hooks for special cases.

SethTisue · 2018-06-06T23:43:54Z

at https://contributors.scala-lang.org/t/lets-drop-postfix-operators/1457/11?u=sethtisue @LPTK expressed skepticism about the desirability of actually removing this in 2.14.

I think the other changes in this PR take care of disarming the footgun. so maybe the actual removal under -Xsource:2.14 isn't really necessary? I don't have a strong feeling about it, but I think it's worth a last thought before merge.

SethTisue · 2018-06-06T23:45:14Z

note also @sjrd's remarks at https://contributors.scala-lang.org/t/lets-drop-postfix-operators/1457/2?u=sethtisue, which @LPTK echoed

SethTisue · 2018-06-06T23:49:19Z

one more thought: I think the error message should be more explicit that this "feature" is actually highly undesirable, likely to be removed in a future Scala, and is still supported at all only for backward compatibility and for no other reason.

this isn't a "proceed, but with caution" type thing anymore like higherKinds and so on... this one is a "no, really, please don't"

som-snytt · 2018-06-20T17:48:19Z

@SethTisue Please take a look at the doc change in the last commit.

Use stronger language to dissuade from postfix, and make the descriptions more uniform. Distinguish required and convenience flags in docs.

som-snytt · 2018-06-20T17:59:45Z

@adriaanm Moved the post-starr commit to the linked PR, in case that's the right thing to do.

SethTisue · 2018-06-25T19:33:32Z

Please take a look at the doc change in the last commit

LGTM except that I'd suggest appending " (not recommended)" here

+ *   - [[postfixOps          `postfixOps`]]          enables postfix operator notation

som-snytt · 2018-06-25T20:11:04Z

OK, I'll add " (not Seth-approved)" or " (not recommended by Seth, who knows)", whichever you prefer. I guess I'll know your preference by your reply to this comment. Actually, following Lacan, it should be, " (not recommended by Seth, the subject supposed to know)".

SethTisue · 2018-06-25T20:35:13Z

the -Y is an other

som-snytt · 2018-07-16T19:05:26Z

@adriaanm @SethTisue if we can move this along, I'll have time to help with community build issues.

I feel no special animus toward postfix, but hoping for clarity.

It needs restarr for the other PR to put the nail in the coffin.

SethTisue · 2018-07-17T22:59:58Z

does this PR actually make it an error? I'm not seeing that it does:

> scala
[info] Running scala.tools.nsc.MainGenericRunner -usejavacp
Welcome to Scala 2.13.0-20180716-190107-b9e039c (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_172).
Type in expressions for evaluation. Or try :help.

scala> List(1) max
               ^
       warning: postfix operator max should be enabled
       by making the implicit value scala.language.postfixOps visible.
       This can be achieved by adding the import clause 'import scala.language.postfixOps'
       or by setting the compiler option -language:postfixOps.
       See the Scaladoc for value scala.language.postfixOps for a discussion
       why the feature should be explicitly enabled.
res0: Int = 1

SethTisue · 2018-07-17T23:01:20Z

oh, is that because "we'll have to release a new starr"? if so, then 1) can you update the PR title, and 2) yes, let's merge this.

som-snytt · 2018-07-17T23:01:44Z

Yes, #6831

it was done

SethTisue · 2018-07-17T23:55:37Z

postfix ops are looking really nervous now

He-Pin · 2018-11-22T21:04:09Z

Cool~

scala-jenkins added this to the 2.13.0-M4 milestone Apr 25, 2018

som-snytt force-pushed the issue/post-postfix branch from 0fe03f2 to 6d49689 Compare April 26, 2018 04:16

adriaanm modified the milestones: 2.13.0-M4, 2.13.0-M5 Apr 30, 2018

som-snytt force-pushed the issue/post-postfix branch 4 times, most recently from c3ae8a4 to e1d5208 Compare May 9, 2018 07:12

som-snytt mentioned this pull request May 10, 2018

Drop postfix operators scala/scala-dev#462

Closed

lrytz requested a review from adriaanm May 28, 2018 11:18

lrytz assigned adriaanm May 28, 2018

adriaanm previously requested changes Jun 1, 2018

View reviewed changes

som-snytt force-pushed the issue/post-postfix branch from e1d5208 to 3412fe3 Compare June 2, 2018 00:23

som-snytt added 2 commits June 1, 2018 21:44

Reduce postfix ops

b649463

Usages unguarded by language import. In the same neighborhood, reduce infix as well.

Reduce postfix ops in tests

b3ca049

som-snytt force-pushed the issue/post-postfix branch from 3412fe3 to d91f4a4 Compare June 2, 2018 04:44

som-snytt added 2 commits June 4, 2018 09:02

Make checkfeature more expressionistic

7b78f3b

Juicier language for language feature object

4d025a7

Use stronger language to dissuade from postfix, and make the descriptions more uniform. Distinguish required and convenience flags in docs.

som-snytt force-pushed the issue/post-postfix branch from 0002c19 to 4d025a7 Compare June 20, 2018 17:54

som-snytt mentioned this pull request Jun 20, 2018

Make postfixOps syntax an error (not just a warning) unless the feature is explicitly enabled [ci: last-only] #6831

Merged

SethTisue changed the title ~~Make postfixOps more opt-in~~ Make postfixOps syntax an error (not just a warning) unless the feature is explicitly enabled Jun 25, 2018

som-snytt mentioned this pull request Jul 13, 2018

Optimize mkString and addString #6878

Merged

Disrecommend postfix more explicitly

b9e039c

SethTisue added the release-notes worth highlighting in next release notes label Jul 17, 2018

SethTisue removed the release-notes worth highlighting in next release notes label Jul 17, 2018

som-snytt changed the title ~~Make postfixOps syntax an error (not just a warning) unless the feature is explicitly enabled~~ Prepare to make postfixOps syntax an error (not just a warning) unless the feature is explicitly enabled Jul 17, 2018

SethTisue merged commit 2de8b62 into scala:2.13.x Jul 17, 2018

som-snytt deleted the issue/post-postfix branch July 18, 2018 01:42

GeorgiChochov mentioned this pull request Apr 26, 2019

#348 Implement _INFO file comparison AbsaOSS/enceladus#354

Merged

ashawley mentioned this pull request Jul 25, 2019

Small cheatsheet fixes scala/docs.scala-lang#1461

Merged

eyalroth mentioned this pull request Aug 31, 2019

can't compile scala 2.13.0 gradle/gradle#9857

Closed

eyalroth mentioned this pull request Sep 9, 2019

Scala 2.13 does not compile with Gradle on Windows scala/bug#11731

Closed

Prepare to make postfixOps syntax an error (not just a warning) unless the feature is explicitly enabled #6559

Prepare to make postfixOps syntax an error (not just a warning) unless the feature is explicitly enabled #6559

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