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retronym opened this issue Aug 5, 2015 · 11 comments
Open

Improve line number information #3

retronym opened this issue Aug 5, 2015 · 11 comments
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feature t:optimizer
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@retronym
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retronym commented Aug 5, 2015

Ensure that standard line number information is kept when inlining from the same file, eliminated otherwise. Write tests.

Next step: add support for JSR-45 debugging info, which allows

  • line numbers of multiple source files within one classfile
  • full (project-relative?) path of source file, not only the file name, should help debuggers in when not using Java's package/directory convention for sources
retronym added a commit that referenced this issue Aug 24, 2015
@retronym
Fix tracing of implicit search under -Ytyper-debug
39ea54b 
The log messages intented to chronicle implicit search were
always being filtered out by virtue of the fact that the the tree
passed to `printTyping` was already typed, (e.g. with an implicit
MethodType.)

This commit enabled printing in this case, although it still
filters out trees that are deemed unfit for typer tracing,
such as `()`. In the context of implicit search, this happens
to filter out the noise of:

```
|    |    |    [search #2] start `()`, searching for adaptation to pt=Unit => Foo[Int,Int] (silent: value <local Test> in Test) implicits disabled
|    |    |    [search #3] start `()`, searching for adaptation to pt=(=> Unit) => Foo[Int,Int] (silent: value <local Test> in Test) implicits disabled
|    |    |    \-> <error>
```

... which I think is desirable.

The motivation for this fix was to better display the interaction
between implicit search and type inference. For instance:

```
class Foo[A, B]
class Test {
  implicit val f: Foo[Int, String] = ???
  def t[A, B](a: A)(implicit f: Foo[A, B]) = ???
  t(1)
}
```

````
% scalac -Ytyper-debug sandbox/instantiate.scala
...
|    |-- t(1) BYVALmode-EXPRmode (site: value <local Test> in Test)
|    |    |-- t BYVALmode-EXPRmode-FUNmode-POLYmode (silent: value <local Test> in Test)
|    |    |    [adapt] [A, B](a: A)(implicit f: Foo[A,B])Nothing adapted to [A, B](a: A)(implicit f: Foo[A,B])Nothing
|    |    |    \-> (a: A)(implicit f: Foo[A,B])Nothing
|    |    |-- 1 BYVALmode-EXPRmode-POLYmode (site: value <local Test> in Test)
|    |    |    \-> Int(1)
|    |    solving for (A: ?A, B: ?B)
|    |    solving for (B: ?B)
|    |    [search #1] start `[A, B](a: A)(implicit f: Foo[A,B])Nothing` inferring type B, searching for adaptation to pt=Foo[Int,B] (silent: value <local Test> in Test) implicits disabled
|    |    [search #1] considering f
|    |    [adapt] f adapted to => Foo[Int,String] based on pt Foo[Int,B]
|    |    [search #1] solve tvars=?B, tvars.constr= >: String <: String
|    |    solving for (B: ?B)
|    |    [search #1] success inferred value of type Foo[Int,=?String] is SearchResult(Test.this.f, TreeTypeSubstituter(List(type B),List(String)))
|    |    |-- [A, B](a: A)(implicit f: Foo[A,B])Nothing BYVALmode-EXPRmode (site: value <local Test> in Test)
|    |    |    \-> Nothing
|    |    [adapt] [A, B](a: A)(implicit f: Foo[A,B])Nothing adapted to [A, B](a: A)(implicit f: Foo[A,B])Nothing
|    |    \-> Nothing
```
@lrytz
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lrytz commented May 17, 2016

also https://issues.scala-lang.org/browse/SI-7518

@fommil
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fommil commented Mar 7, 2017

Would this be appropriate for a scala center proposal?

@fommil
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fommil commented Mar 7, 2017

btw, we already (in ensime) handle the source file lookup issue in ensime using our indexer.

Does this JSR-45 support include information such as expanding line numbers to source ranges? The problem faced when writing a debugger is that we only get line number info, but we want to highlight the block of code (rangepos) that is being evaluated.

Of course, stacktrace demangling is another issue...

@som-snytt
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som-snytt commented Mar 12, 2017 •
edited
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Relatedly https://issues.scala-lang.org/browse/SI-8526 for macro API.

@fommil
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fommil commented Mar 12, 2017

This has gone a bit cold, could somebody please help me with technical input to write a proposal?

@fommil
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fommil commented Mar 12, 2017

GSoC needs a mentor, which would be hard for this. We also have a debugging proposal already :-)

Scala Center is ideal for this if Lightbend's customers aren't prepared to directly fund it, because it really needs somebody working closely with EPFL or core scala team.

@fommil
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fommil commented Mar 22, 2017

I've put together a draft SC proposal here if anybody has any comments: https://gist.github.com/fommil/1867119e7f184d36342bd5e4b34c7bfe

@lrytz lrytz mentioned this issue Mar 7, 2018
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@SethTisue
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SethTisue commented Dec 16, 2019 •
edited
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Scala Center proposals in this area:

  • SCP-011 was accepted in 2017, but never really happened
  • SCP-022 proposes resuming work on it (and targeting Scala 3 as well)

@SethTisue
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SethTisue commented Jul 1, 2020 •
edited by dwijnand
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further on SCP-022: https://contributors.scala-lang.org/t/improving-the-scala-debugging-experience/4264

cc @errikos, who might not know about this ticket

@dwijnand
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@errikos does your work on JSR 45 (scala/scala#9121) cover this as well, do you think?

@dwijnand dwijnand added this to the Backlog milestone Oct 22, 2020
@errikos
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errikos commented Nov 16, 2020

Hello. Sorry for the late reply.

Yes, it covers both bullets. For the second one, we store the fully qualified class name, so not project relative path exactly.

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@retronym @lrytz @SethTisue @dwijnand @som-snytt @fommil @errikos