The discussion here seems to assume that T[N] is syntax for the type 'an array of N elements of type T'. But that implies that a multidimensional array type like T[N][M] should be parenthesized as (T[N])[M]: an array of M elements, each of which is an array of N elements of type T. In this syntax, sizes of multidimensional arrays appear from inner to outer as one reads from left to right, because the inner type is written before the size of the array containing it.

This is the transpose of the way C and GLSL interpret T[N][M]: they treat that as an array of N elements, each of which is an array of M elements of type T. The proposal here is also backwards relative to the way arrays are indexed in expressions, where outer indices appear first.

For this proposal to work, the syntax would need to be something like:

unsubscripted-type subscript ...

where:

unsubscripted-type subscript... final-subscript

gets parenthesized as:

( unsubscripted-type final-subscript ) subscript...

In other words, the grammar must grab all the subscripts at once, and apply them to the inner type from right to left.

Note that Rust gets this sort of thing 'wrong': let x: [[i32; 10]; 4] = ...; gives you an array of 4 arrays of length 10. When you write x[i][j], i can range from 0 to 4, and j can range from 0 to 10. So the sizes apply to the indices in reverse order. The way the array syntax surrounds the element type arguably helps make this explicit, but it's still not good.

This is why Go has you write [N]T for 'array of N elements each of type T': [M][N]T parenthesizes naturally as [M]([N]T), so the sizes appear from major to minor, as expected.

(I think it was a great choice for WGSL to avoid C-style type syntax, and not hide the identifier being declared in the midst of syntax specifying its type. But in doing so, we've traded int x[5] for x: int[5], and swapping the positions of the type and the identifier has consequences - the confusion here being one of them.)

Use brackets for array types #854

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