Previously casting a bool to an int would result in the following Zig code:
@intCast(c_int, @bitCast(i1, @intCast(u1, @boolToInt(b))));
This is incorrect if `b` is true, since bitcasting a `u1` with the value 1
to an `i1` will result in the value -1. Instead, generate the following code:
@as(c_int, @boolToInt(b));
Since @boolToInt returns a `u1`, this is only disallowed if the destination
type is one-bit and signed, which can only happen if it's a bitfield
(currently not supported by translate-c)
C compiler intrinsics can only appear as part of a function call. When called
they are implicitly cast to a function pointer; treat this as a non-null
pointer so that it emits as a regular Zig function call.
Put `pub usingnamespace @import("std").c.builtins;` at the top of translated
C files so that they will have access to builtin functions defined there.
Fixes#6707
In C, enums are represented as signed integers, so casting from an enum to an integer
should use the "cast integer to integer" translation code path. Previously it used the
"cast enum to generic non-enum" code path, because enums were not being treated as integers.
Ultimately this can produce zig code that fails to compile if the destination type does not
support the full range of enum values (e.g. translated C code that casts an enum value to an
unsigned integer would fail to compile since enums are signed integers, and unsigned integers
cannot represent the full range of values that signed ones can).
One interesting thing that came up during testing is that the implicit enum-to-int cast that
occurs when an enum is used in a boolean expression was parsed as an (int) by some versions of
the zig compiler, and an (unsigned int) cast by others. Specifically, the following code:
```c
enum Foo {Bar, Baz};
// ...
enum Foo foo = Bar;
if (0 || foo) {
// do something
}
```
When tested on MacOS, Linux, and Windows using a compiler built from the Windows Zig Compiler
Dev Kit, the above code would emit a cast to c_uint:
`if (false or (@bitCast(c_uint, @enumToInt(foo)) != 0)) {}`
However when tested on Windows with a Zig compiler built using MSVC, it produces:
`if (false or (@bitCast(c_int, @enumToInt(foo)) != 0)) {}`
In this particular case I don't think it matters, since a c_int and c_uint will have the same
representation for zero, but I'm not sure if this is ultimately the result of
implementation-defined behavior or something else.
Because of this, I added explicit casts in the `translate_c.zig` tests, to ensure that the
emitted zig source exactly matches across platforms. I also added a behavior test in
`run_translated_c.zig` that uses the old implicit casts from `translate_c.zig` to ensure
that the emitted Zig code behaves the same as the C code regardless of what cast is used.
Pre-requisite for having a test case for #5062
In complex C statements which are outside of macros,
it is valid C to perform e.g. a bitor between an
integer and a boolean `5 | (8 == 9)`
Currently this results in a zig error after translating
as `c_int | bool` is invalid Zig.
Detects if a sub-expression of a numeric operator is
boolean and if so converts it to int
Translate C: Put an alignCast in c style pointer casts to allow opaque types to cast properly in C macros
Translate C: add test case for aligning opaque types in pointer casts
Translate C: Fix @typeId -> @typeInfo
Add test case to run_translated_c for casting from pointer to opaque type
