Proposal: syntactic sugar for initializing Span<char> by stackalloc with string literal

[acid-chicken]

Summary

Provide a syntactic sugar which initializes Span and ReadOnlySpan with stackalloc keyword by string literal.

Design

Span<char> span = stackalloc [] "initial characters";

will be converted to

Span<char> span = stackalloc [] { 'i', 'n', 'i', 't', 'i', 'a', 'l', ' ', 'c', 'h', 'a', 'r', 'a', 'c', 't', 'e', 'r', 's' };

Choices

Syntax Style

Span<char> span = stackalloc [] "initial characters";

or

Span<char> span = stackalloc "initial characters";

or

Span<char> span = stackalloc char[] "initial characters";
/* NEED TO SPECIFY TYPE STRICTLY */

or other?

Also Support char[]

Also adding syntactic suger for char[] initializer?

[svick]

Why? Are there any cases where memory consumed by string literals is an issue?

[jnm2]

@svick I read this as wanting to initialize the space from a string literal but then using it as scratch space.

[svick]

@jnm2

Oh, so the equivalent of the following code?

string s = "initial characters";
Span<char> span = stackalloc char[s.Length];
s.AsSpan().CopyTo(span);

Is that actually so common that it needs syntactic sugar?

[AraHaan]

I do not think so. I did not even know about Span in c#.

[jnm2]

@svick That's what I understood @acid-chicken to mean. I haven't run into this pattern before, though I have been in situations where I'd copy a literal to the beginning of a longer buffer.

If the stack space isn't going to be mutated after copying the literal into it, I'd just get the pointer to the literal directly without allocating stack space and doing the copy (or use ReadOnlySpan).