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nicolasstucki opened this issue Apr 15, 2017 · 3 comments · Fixed by #14853
Closed

Lazy val with constant type loses side effects. #2266

nicolasstucki opened this issue Apr 15, 2017 · 3 comments · Fixed by #14853
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@odersky
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itype:bug
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3.2.0

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@nicolasstucki
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lazy val x: true = { println("X"); true }
x

does not print X.
@nicolasstucki nicolasstucki mentioned this issue Apr 15, 2017
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DarkDimius added a commit that referenced this issue Apr 19, 2017
@DarkDimius
Merge pull request #2267 from dotty-staging/fix-constant-lazy-vals
02e3883 
Fix #2266: Do not replace constant type lazy vals with constant.
@felixmulder felixmulder reopened this Apr 26, 2017
@propensive propensive changed the title Lazy val with constant type looses side effects. Lazy val with constant type loses side effects. Apr 27, 2017
odersky added a commit that referenced this issue Apr 29, 2017
@odersky
Merge pull request #2308 from lampepfl/revert-2267-fix-constant-lazy-…
16a28ac 
…vals

Revert "Fix #2266: Do not replace constant type lazy vals with constant."
@panacekcz
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Should this issue be opened? Looks like it was closed automatically by a commit that reverted the fix.
The problem in general seems to be the same as in #4765, but in a different context.

@nicolasstucki nicolasstucki reopened this Oct 10, 2018
@Blaisorblade Blaisorblade mentioned this issue Jan 15, 2019
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@odersky odersky self-assigned this Apr 5, 2022
@odersky
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odersky commented Apr 5, 2022

scalac prints the "X", so this is a change in behavior that should be fixed.

@som-snytt
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👍

Also, Scala 3 is also scalac. It is not some other thing.

odersky added a commit to dotty-staging/dotty that referenced this issue Apr 5, 2022
@odersky
Fix constToLiteral
b5fad12 
We previously converted an expression with constant type to a literal if
the expression was idempotent. This can hide side effects in the case where
the expression is a selection from an object or lazy val. Demanding purity
instead prodcues tons of errors involving inline vals on objects.

We now demand idempotency if the expression refers to an inline val (or
an operation over an inline val), and purity elsewhere.

Fixes scala#2266
odersky added a commit to dotty-staging/dotty that referenced this issue Apr 5, 2022
@odersky
Fix constToLiteral
6df2c6e 
We previously converted an expression with constant type to a literal if
the expression was idempotent. This can hide side effects in the case where
the expression is a selection from an object or lazy val. Demanding purity
instead prodcues tons of errors involving inline vals on objects.

We now demand idempotency if the expression refers to an inline val (or
an operation over an inline val), and purity elsewhere.

Fixes scala#2266
@odersky odersky mentioned this issue Apr 5, 2022
Merged
@Kordyjan Kordyjan added this to the 3.2.0 milestone Aug 1, 2023
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Fix constToLiteral dotty-staging/dotty
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@smarter @som-snytt @odersky @felixmulder @nicolasstucki @panacekcz @Kordyjan