This change implements the following syntax into the compiler:
```zig
const x: u32, var y, foo.bar = .{ 1, 2, 3 };
```
A destructure expression may only appear within a block (i.e. not at
comtainer scope). The LHS consists of a sequence of comma-separated var
decls and/or lvalue expressions. The RHS is a normal expression.
A new result location type, `destructure`, is used, which contains
result pointers for each component of the destructure. This means that
when the RHS is a more complicated expression, peer type resolution is
not used: each result value is individually destructured and written to
the result pointers. RLS is always used for destructure expressions,
meaning every `const` on the LHS of such an expression creates a true
stack allocation.
Aside from anonymous array literals, Sema is capable of destructuring
the following types:
* Tuples
* Arrays
* Vectors
A destructure may be prefixed with the `comptime` keyword, in which case
the entire destructure is evaluated at comptime: this means all `var`s
in the LHS are `comptime var`s, every lvalue expression is evaluated at
comptime, and the RHS is evaluated at comptime. If every LHS is a
`const`, this is not allowed: as with single declarations, the user
should instead mark the RHS as `comptime`.
There are a few subtleties in the grammar changes here. For one thing,
if every LHS is an lvalue expression (rather than a var decl), a
destructure is considered an expression. This makes, for instance,
`if (cond) x, y = .{ 1, 2 };` valid Zig code. A destructure is allowed
in almost every context where a standard assignment expression is
permitted. The exception is `switch` prongs, which cannot be
destructures as the comma is ambiguous with the end of the prong.
A follow-up commit will begin utilizing this syntax in the Zig compiler.
Resolves: #498
Most of this migration was performed automatically with `zig fmt`. There
were a few exceptions which I had to manually fix:
* `@alignCast` and `@addrSpaceCast` cannot be automatically rewritten
* `@truncate`'s fixup is incorrect for vectors
* Test cases are not formatted, and their error locations change
This can be used to escape the usual meaning of `_` to indicate a
non-exhaustive enum and create an enum tag that is a literal underscore,
so zig fmt should allow this syntax.
Before, zig fmt changes
const E = enum { @"_" };
to the semantically different
const E = enum { _ };
After, it remains the same.
The majority of these are in comments, some in doc comments which might
affect the generated documentation, and a few in parameter names -
nothing that should be breaking, however.
Fixes#11353
The renderer treats comments and doc comments differently since doc
comments are parsed into the Ast. This commit adds a check after getting
the text for the doc comment and trims whitespace at the end before
rendering.
The `a = 0,` in the test is here to avoid a ParseError while parsing the
test.
* Fixes#8810.
* Prevent a single-line container declaration if it contains a comment
or multiline string.
* If a container declaration cannot be single-line, ensure container
fields are rendered with a trailing comma.
* If `Space.comma` is passed to `renderExpressionComma` or
`renderTokenComma`, and there already exists a comma in the source,
then render one comma instead of two.
* Remove the builtins `@addWithSaturation`, `@subWithSaturation`,
`@mulWithSaturation`, and `@shlWithSaturation` now that we have
first-class syntax for saturating arithmetic.
* langref: Clarify the behavior of `@shlExact`.
* Ast: rename `bit_shift_left` to `shl` and `bit_shift_right` to `shr`
for consistency.
* Air: rename to include underscore separator with consistency with
the rest of the ops.
* Air: add shl_exact instruction
* Use non-extended tags for saturating arithmetic, to keep it
simple so that all the arithmetic operations can be done the same
way.
- Sema: unify analyzeArithmetic with analyzeSatArithmetic
- implement comptime `+|`, `-|`, and `*|`
- allow float operands to saturating arithmetic
* `<<|` allows any integer type for the RHS.
* C backend: fix rebase conflicts
* LLVM backend: reduce the amount of branching for arithmetic ops
* zig.h: fix magic number not matching actual size of C integer types
