This is similar to my question in How can I resolve sorbet error: "Use of undeclared variable"?, but for constants.
I am experimenting with adding sorbet type information to my gem, pdf-reader. I don't want sorbet to be a runtime dependency for the gem, so all type annotations are in an external file in the rbi/ directory. I also can't extend T::Sig in my classes, and I can't use T.let in my code.
I'd like to enable typed: strict in some files, but doing so flags that constants don't have type annotations:
$ be srb tc
./lib/pdf/reader/buffer.rb:41: Constants must have type annotations with T.let when specifying # typed: strict https://srb.help/7027
41 | TOKEN_WHITESPACE=[0x00, 0x09, 0x0A, 0x0C, 0x0D, 0x20]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Autocorrect: Use `-a` to autocorrect
./lib/pdf/reader/buffer.rb:41: Replace with T.let([0x00, 0x09, 0x0A, 0x0C, 0x0D, 0x20], T::Array[Integer])
41 | TOKEN_WHITESPACE=[0x00, 0x09, 0x0A, 0x0C, 0x0D, 0x20]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
./lib/pdf/reader/buffer.rb:42: Constants must have type annotations with T.let when specifying # typed: strict https://srb.help/7027
42 | TOKEN_DELIMITER=[0x25, 0x3C, 0x3E, 0x28, 0x5B, 0x7B, 0x29, 0x5D, 0x7D, 0x2F]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Autocorrect: Use `-a` to autocorrect
./lib/pdf/reader/buffer.rb:42: Replace with T.let([0x25, 0x3C, 0x3E, 0x28, 0x5B, 0x7B, 0x29, 0x5D, 0x7D, 0x2F], T::Array[Integer])
42 | TOKEN_DELIMITER=[0x25, 0x3C, 0x3E, 0x28, 0x5B, 0x7B, 0x29, 0x5D, 0x7D, 0x2F]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
./lib/pdf/reader/buffer.rb:55: Constants must have type annotations with T.let when specifying # typed: strict https://srb.help/7027
55 | WHITE_SPACE = [LF, CR, ' ']
^^^^^^^^^^^^^
Autocorrect: Use `-a` to autocorrect
./lib/pdf/reader/buffer.rb:55: Replace with T.let([LF, CR, ' '], T::Array[String])
55 | WHITE_SPACE = [LF, CR, ' ']
^^^^^^^^^^^^^
Errors: 3
The proposed fix is to use T.let(). However I can't do that because it requires a runtime dependency on sorbet.
I tried using T.let() in my RBI file, similar to how we solved the instance variable issue in the linked question. However, that seems to have no effect for this error:
diff --git a/rbi/pdf-reader.rbi b/rbi/pdf-reader.rbi
index 113f183..f392b0a 100644
--- a/rbi/pdf-reader.rbi
+++ b/rbi/pdf-reader.rbi
@@ -81,7 +81,7 @@ module PDF
CR = "\r"
LF = "\n"
CRLF = "\r\n"
- WHITE_SPACE = [LF, CR, ' ']
+ WHITE_SPACE = T.let(T.unsafe(nil), T::Array[String])
TRAILING_BYTECOUNT = 5000
sig { returns(Integer) }
Interestingly, if I change the T.let() in the RBI file to something obviously wrong like:
diff --git a/rbi/pdf-reader.rbi b/rbi/pdf-reader.rbi
index 113f183..251d80d 100644
--- a/rbi/pdf-reader.rbi
+++ b/rbi/pdf-reader.rbi
@@ -81,7 +81,7 @@ module PDF
CR = "\r"
LF = "\n"
CRLF = "\r\n"
- WHITE_SPACE = [LF, CR, ' ']
+ WHITE_SPACE = T.let(T.unsafe(nil), T::Array[Integer])
TRAILING_BYTECOUNT = 5000
sig { returns(Integer) }
Then I get a type error:
$ srb tc
./lib/pdf/reader/buffer.rb:55: Expected T::Array[Integer] but found T::Array[String] for field https://srb.help/7013
55 | WHITE_SPACE = [LF, CR, " "]
^^^^^^^^^^^^^
Expected T::Array[Integer] for field defined here:
./lib/pdf/reader/buffer.rb:55:
55 | WHITE_SPACE = [LF, CR, " "]
^^^^^^^^^^^
Got T::Array[String] originating from:
./lib/pdf/reader/buffer.rb:55:
55 | WHITE_SPACE = [LF, CR, " "]
^^^^^^^^^^^^^
It seems like T.let() for constants in an RBI file isn't ignored, but it's not enough to satisfy the strict requirement for the type of constants to be defined.
# TLDR
# NOTE: temporary fix, because this looks like a sorbet bug/feature;
# if you're getting inconsistent results use --max-threads=1
$ srb typecheck --stress-incremental-resolver
This is the minimal setup to reproduce the issue:
# Gemfile
source "https://rubygems.org"
gem 'sorbet'
# lib/my_gem.rb
module MyGem
WHITE_SPACE = [' ']
end
# sorbet/rbi/my_gem.rbi
module MyGem
# NOTE: Based on sorbet docs, this should tell sorbet the type of this constant
# and should be equivalent to doing this in `lib/my_gem.rb`:
# WHITE_SPACE = T.let([' '], T::Array[String])
WHITE_SPACE = T.let(T.unsafe(nil), T::Array[String])
end
# srb --version
# Sorbet typechecker 0.5.10010 git d2cd1e574d70b4485d961fdf1f457948e4d3988d debug_symbols=true clean=0
# ruby --version
# ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [x86_64-linux]
Running a strict typecheck fails:
$ srb typecheck --typed=strict --dir .
lib/my_gem.rb:2: Constants must have type annotations with T.let when specifying # typed: strict https://srb.help/7027
2 | WHITE_SPACE = [' ']
^^^^^
There is a resolver flag that changes something somewhere, total guess on my part, that fixes the error:
$ srb typecheck --help
...
--stress-incremental-resolver
Force incremental updates to discover resolver & namer bugs
...
$ srb typecheck --stress-incremental-resolver --typed=strict --dir .
No errors! Great job.
To verify that it actually does the typecheck, we can change the .rbi file to something incorrect:
# sorbet/rbi/my_gem.rbi
module MyGem
WHITE_SPACE = T.let(T.unsafe(nil), T::Array[Integer])
end
$ srb typecheck --stress-incremental-resolver --typed=strict --dir .
lib/my_gem.rb:42: Expected T::Array[Integer] but found [String(" ")] for field https://srb.help/7013
42 | WHITE_SPACE = [' ']
^^^^^
Seems to work and looks like it resolves the constant type correctly all by itself => [String(" ")] which doesn't match [Integer].
Digging a little deeper shows that sorbet parses/rewrites/desugars our file differently with the resolver flag:
$ srb typecheck --print=resolve-tree --typed=strict --dir .
begin
class <emptyTree><<C <root>>> < (::<todo sym>)
nil
end
<emptyTree>
end
begin
class <emptyTree><<C <root>>> < (::<todo sym>)
begin
module ::MyGem<<C MyGem>> < ()
#
# NOTE: This `Magic` bit in particular is not present with --stress-incremental-resolver
#
::MyGem::WHITE_SPACE = ::<Magic>.<suggest-type>([" "])
end
::Sorbet::Private::Static.keep_for_ide(::MyGem)
<emptyTree>
end
end
<emptyTree>
end
begin
class <emptyTree><<C <root>>> < (::<todo sym>)
begin
module ::MyGem<<C MyGem>> < ()
::MyGem::WHITE_SPACE = begin
::Sorbet::Private::Static.keep_for_typechecking(::T::Array.[](::String))
T.let(::T.unsafe(nil), AppliedType {
klass = <C <U Array>>
targs = [
<C <U Elem>> = String
]
})
end
end
::Sorbet::Private::Static.keep_for_ide(::MyGem)
<emptyTree>
end
end
<emptyTree>
end
The <Magic>.<suggest-type> maps to this method:
https://github.com/sorbet/sorbet/blob/0.5.10010.20220513160354-d2cd1e574/core/types/calls.cc#L2642
That method works fine with plain string ' ', but throws an error with arrays [' '] even though everything looks resolved, indicated by ... found [String(" ")] ... above. Is it a feature or a bug is TBD.
Also, converting WHITE_SPACE from a constant to a method could be a solution.