Skip to content

Allow arrays of nullable reference types #1386

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
wants to merge 3 commits into
base: draft-v8
Choose a base branch
from
Draft

Allow arrays of nullable reference types #1386

Changes from 1 commit
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
066fbfc
Fix grammar to allow arrays of nullable reference types
jnm2 Jul 31, 2025
aa5e4b5
Document the exception to the rule that nullable annotations can be i…
jnm2 Jul 31, 2025
74b51aa
Add new rule to avoid parenthesized grammar
jnm2 Aug 9, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 3 additions & 6 deletions standard/types.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -54,16 +54,13 @@
;

array_type
: non_array_type rank_specifier+
: array_type nullable_type_annotation rank_specifier+
| non_array_type rank_specifier+
Comment on lines 56 to +58
Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This has the property that when parsing string?[][,]?[,,][,,,]? we end up with two array_type nodes: one being string?[][,]?[,,][,,,], and one being the inner string?[][,].

@Nigel-Ecma It's not mutual left recursion! 😁

Comment on lines +57 to +58
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Yes, no MLR, well done ;-)

This change impacts §17.2 which now needs to be revised.

;

non_array_type
: value_type

Check warning on line 62 in standard/types.md

View workflow job for this annotation

GitHub Actions / Markdown to Word Converter

standard/types.md#L62 

MDC032::Line length 106 > maximum 81
| class_type
| interface_type
| delegate_type
| 'dynamic'
| type_parameter
| (class_type | interface_type | delegate_type | 'dynamic' | type_parameter) nullable_type_annotation?
Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This fixes the issue where string?[] and other arrays of reference-typed non-arrays were disallowed by the grammar.

| pointer_type // unsafe code support
;

Expand Down Expand Up @@ -946,13 +943,13 @@
> public void M(string s)
> {
> int length = s.Length; // No warning. s is not null
>

Check warning on line 946 in standard/types.md

View workflow job for this annotation

GitHub Actions / Markdown to Word Converter

standard/types.md#L946 

MDC032::Line length 87 > maximum 81
> _ = s == null; // Null check by testing equality. The null state of s is maybe null
> length = s.Length; // Warning, and changes the null state of s to not null
>

Check warning on line 949 in standard/types.md

View workflow job for this annotation

GitHub Actions / Markdown to Word Converter

standard/types.md#L949 

MDC032::Line length 90 > maximum 81
> _ = s?.Length; // The ?. is a null check and changes the null state of s to maybe null
> if (s.Length > 4) // Warning. Changes null state of s to not null
> {

Check warning on line 952 in standard/types.md

View workflow job for this annotation

GitHub Actions / Markdown to Word Converter

standard/types.md#L952 

MDC032::Line length 87 > maximum 81
> _ = s?[4]; // ?[] is a null check and changes the null state of s to maybe null
> _ = s.Length; // Warning. s is maybe null
> }
Expand Down Expand Up @@ -1012,7 +1009,7 @@
> {
> var t = new Test();
> if (t.DisappearingProperty != null)
> {

Check warning on line 1012 in standard/types.md

View workflow job for this annotation

GitHub Actions / Markdown to Word Converter

standard/types.md#L1012 

MDC032::Line length 110 > maximum 81
> int len = t.DisappearingProperty.Length; // No warning. A compiler can assume property is stateful
> }
> }
Expand Down
Loading