Make Span::initial() a const fn #143
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
In Arret nearly every intermediate data structure contains a `Span` so our generated code can be mapped back to source location. However, they're rarely used until we need to report a diagnostic or generate debugging information. This led to a common pattern in unit tests where we use a dummy span to test intermediate transformations where we aren't starting from actual Arret source. This used to be a `const` called `EMPTY_SPAN` which can be used to build other `const` data structures used for testing. In etaoins/arret#160 we needed to switch to an `empty_span()` function because there is no longer a `const` constructor for `Span`. We can't make `Span::new` `const` yet because const functions are not powerful enough. However, `Span::initial` is perfect for this use case.
|
Thanks! |
etaoins
added a commit
to etaoins/arret
that referenced
this pull request
Jan 5, 2020
This is enabled by brendanzab/codespan#143 which requires us to take a Git dependency until `codespan` 0.7 is released.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
In Arret nearly every intermediate data structure contains a
Spanso our generated code can be mapped back to source location. However, they're rarely used until we need to report a diagnostic or generate debugging information.This led to a common pattern in unit tests where we use a dummy span to test intermediate transformations where we aren't starting from actual Arret source. This used to be a
constcalledEMPTY_SPANwhich can be used to build otherconstdata structures used for testing.In etaoins/arret#160 we needed to switch to an
empty_span()function because there is no longer aconstconstructor forSpan.We can't make
Span::newconstyet because const functions are not powerful enough. However,Span::initialis perfect for this use case.