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lost expected assignment after "const" error #45024

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JeffBezanson opened this issue Apr 18, 2022 · 1 comment · Fixed by #45344
Closed

lost expected assignment after "const" error #45024

JeffBezanson opened this issue Apr 18, 2022 · 1 comment · Fixed by #45344
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@JeffBezanson
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kind:regression Regression in behavior compared to a previous version parser Language parsing and surface syntax
Milestone
1.8

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@JeffBezanson
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julia> const x
ERROR: `body` expression must terminate in `return`. Use `block` instead.

julia> const x::Int
# allowed

These both used to give the "expected assignment" error. This is because we need to parse const x inside struct definitions, and const x is a valid IR form but not generally allowed as input syntax. We need to either fix the error, or decide to allow const x (which declares x constant without giving it a value, which is a state we didn't want to be observable for too long).
@JeffBezanson JeffBezanson added kind:regression Regression in behavior compared to a previous version parser Language parsing and surface syntax labels Apr 18, 2022
@JeffBezanson JeffBezanson added this to the 1.8 milestone Apr 18, 2022
@JeffBezanson JeffBezanson self-assigned this Apr 18, 2022
@JeffBezanson
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If we fix this in lowering, there's a chance it could be breaking. We currently allow lowering code containing Expr(:const, :x). If we need to keep allowing that, the only way to give an error is during parsing, so we would need to selectively disable the error inside structs.

@simeonschaub simeonschaub mentioned this issue Apr 24, 2022
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JeffBezanson added a commit that referenced this issue May 17, 2022
@JeffBezanson
fix #45024, lost expected assignment after const error
3e70d57
@JeffBezanson JeffBezanson mentioned this issue May 17, 2022
Merged
KristofferC pushed a commit that referenced this issue May 18, 2022
@JeffBezanson
fix #45024, lost expected assignment after const error (#45344)
2d40898
KristofferC pushed a commit that referenced this issue May 18, 2022
@JeffBezanson @KristofferC
fix #45024, lost expected assignment after const error (#45344)
e4d2f0f 
(cherry picked from commit 2d40898)
KristofferC pushed a commit that referenced this issue May 18, 2022
@JeffBezanson @KristofferC
fix #45024, lost expected assignment after const error (#45344)
1ccb618 
(cherry picked from commit 2d40898)
@c42f c42f mentioned this issue Oct 25, 2022
Closed
c42f added a commit to JuliaLang/JuliaSyntax.jl that referenced this issue Oct 26, 2022
@c42f
Fix const struct field errors + cleanup global const AST
bd79bd4 
Here I've replicated the fix from JuliaLang/julia#45024 so that
`const x` (ie, without an assignment) is only valid within a `struct`
and is otherwise an error.

Also avoid lowering the syntax `global const` into `const global` within
the parser; do this in Expr conversion instead. This more closely
reflects the structure of the source, allowing trivia attachment to be
more natural.
@c42f c42f mentioned this issue Oct 26, 2022
Merged
c42f added a commit to JuliaLang/JuliaSyntax.jl that referenced this issue Oct 26, 2022
@c42f
Fix const struct field errors + cleanup global const AST (#130)
86d7f90 
Here I've replicated the fix from JuliaLang/julia#45024 so that
`const x` (ie, without an assignment) is only valid within a `struct`
and is otherwise an error.

Also avoid lowering the syntax `global const` into `const global` within
the parser; do this in `Expr` conversion instead. This more closely
reflects the structure of the source, allowing trivia attachment to be
more natural.
@Tortar Tortar mentioned this issue Jul 22, 2023
Merged
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kind:regression Regression in behavior compared to a previous version parser Language parsing and surface syntax
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fix #45024, lost expected assignment after const error JuliaLang/julia
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