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translate-c: determine sizeof using std.meta.sizeof

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Vexu 2020-09-14 23:53:38 +03:00
parent 29fd0c6d61
commit a3624e94f8
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2 changed files with 43 additions and 4 deletions
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31
lib/std/meta.zig
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@ -795,3 +795,34 @@ test "std.meta.cast" {
testing.expectEqual(@as(u32, 10), cast(u32, @as(u64, 10)));
testing.expectEqual(@as(u8, 2), cast(u8, E.Two));
}
/// Given a value returns its size as C's sizeof operator would.
/// This is for translate-c and is not intended for general use.
pub fn sizeof(target: anytype) usize {
switch (@typeInfo(@TypeOf(target))) {
.Type => return @sizeOf(target),
.Float, .Int, .Struct, .Union, .Enum => return @sizeOf(@TypeOf(target)),
.ComptimeFloat => return @sizeOf(f64), // TODO c_double #3999
.ComptimeInt => {
// TODO to get the correct result we have to translate
// `1073741824 * 4` as `int(1073741824) *% int(4)` since
// sizeof(1073741824 * 4) != sizeof(4294967296).
// TODO test if target fits in int, long or long long
return @sizeOf(c_int);
},
else => @compileError("TODO implement std.meta.sizeof for type " ++ @typeName(@TypeOf(target))),
}
}
test "sizeof" {
const E = extern enum(c_int) { One, _ };
const S = extern struct { a: u32 };
testing.expect(sizeof(u32) == 4);
testing.expect(sizeof(@as(u32, 2)) == 4);
testing.expect(sizeof(2) == @sizeOf(c_int));
testing.expect(sizeof(E) == @sizeOf(c_int));
testing.expect(sizeof(E.One) == @sizeOf(c_int));
testing.expect(sizeof(S) == 4);
}

16
src-self-hosted/translate_c.zig
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@ -6324,10 +6324,18 @@ fn parseCPrefixOpExpr(c: *Context, m: *MacroCtx, scope: *Scope) ParseError!*ast.
break :blk inner;
} else try parseCPrefixOpExpr(c, m, scope);
const builtin_call = try c.createBuiltinCall("@sizeOf", 1);
builtin_call.params()[0] = inner;
builtin_call.rparen_token = try appendToken(c, .RParen, ")");
return &builtin_call.base;
//(@import("std").meta.sizeof(dest, x))
const import_fn_call = try c.createBuiltinCall("@import", 1);
const std_node = try transCreateNodeStringLiteral(c, "\"std\"");
import_fn_call.params()[0] = std_node;
import_fn_call.rparen_token = try appendToken(c, .RParen, ")");
const inner_field_access = try transCreateNodeFieldAccess(c, &import_fn_call.base, "meta");
const outer_field_access = try transCreateNodeFieldAccess(c, inner_field_access, "sizeof");
const sizeof_call = try c.createCall(outer_field_access, 1);
sizeof_call.params()[0] = inner;
sizeof_call.rtoken = try appendToken(c, .RParen, ")");
return &sizeof_call.base;
},
.Keyword_alignof => {
// TODO this won't work if using <stdalign.h>'s