Self hosted parser completion

[Hejsil]

This is in no way done, but I thought, that instead of just pushing my work on the self-hosted parser to master, I would make this PR. This allows me to write a lot of tests that fail, and slowly work towards getting them all passing.

Checklist!

• extern "c" fn puts(s: &const u8) c_int;
• Muti line strings
• Indexing
• Slicing
• Types
  • Array
  • Slice
  • Function
  • error
• Literals
  • Boolean
  • Char
  • null
• unreachable
• this
• Operator precedence and expression grouping (parentheses)
• Struct declaration
• Enum declaration
• Union declaration
• Error set declaration
• Container initializers
• Labeled blocks
• switch
• while
• for
• if
• defer
• catch
• comptime
• Inline assembly
• Coroutines
• use
• Parse std

When all these are checked and the self-hosted parser can parse the entire std library and all tests, then it's ready for a merge.

[andrewrk]

Great work so far. It's been really exciting to watch your progress

[andrewrk]

I think canonical var decl is:
const name: type = value;
(No space between colon and var name)

[bnoordhuis]

'precedence' typo?

[Hejsil]

I've now added test cases for what I hope is all of Zig's syntax. I've also added a checklist with all everything that is missing from the self-hosted parser.

[andrewrk]

I hate it when the cache is unreachable :)

[Hejsil]

Lol, yes :)

[Hejsil]

@andrewrk The variable declaration syntax in the self-hosted parser is currently not being parsed correctly. var a: u8 = 1; is parsed intovar a: ( u8 = 1 ) ;.

In the C++ compiler, this is solved by parsing type expressions as prefix operators first and therefore requiring parentheses for infix operators to be used in type expressions. This solution cannot be used in the self-hosted parser because of the way expressions are parsed.

Do we rewrite expression parsing to make this work or disallow assignment as an expression?

[Hejsil]

There is also the option of checking if the type expression is an assignment and then transform var a: (u8 = 0); -> var a: u8 = 0;. The only problem with this solution is, that we are using an arena as an allocator, so we cannot free the NodeInfixOp node.

[Hejsil]

Also, in the C++ compiler, this is allowed:

var a: u8 = 0;
const b = a = 2;

I don't think this has any use. @typeOf(b) == void, and I don't think that is what a person intended if they wrote this piece of code.

[Hejsil]

This is also a problem when implementing initializers :/

fn main() void {}

Gets parsed as:

fn main() (void {})

[andrewrk]

I think assignments should not be expressions.

[Hejsil]

Alright. Then we just need to solve #760 :)

[andrewrk]

From the appveyor build:
lld: error: undefined symbol: memmove

Wow, I've not seen this happen yet. I guess we need to add a memmove implementation to std/special/builtin.zig.

[andrewrk]

All tests passing, merged!

Let's open new issues for whatever's left.

[tiehuis]

Great work, @Hejsil.