An object literal with methods assigned to a class is an error (#494) - #495
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`const c: C = { x: 3, f() { return 2; } }` compiled, but the instance
was wrong: an object literal with a method or an accessor is boxed (an
`!ts.object`), and its cast to the class was a plain ts.Cast of the
pointer. No instance was built, so `c.x` read the class's field slot
out of memory laid out as `{x, f}` (garbage such as 1.34e-311), and
`c.f()` called through a vtable that was not there (0xC0000005).
A class instance takes its methods from its class's vtable, so one
object cannot have a method of its own; TypeScript, where `c.f()` would
give 2, has no counterpart here. Such a literal is now a compile error,
"an object literal with methods or accessors cannot be assigned to
class 'C': a class instance takes its methods from its class; use
'new', or an interface type", wherever it meets a class type: a
declaration, a parameter, a return, `as C`. A literal with fields only
is still made into an instance (#487), and a literal with methods
assigned to an interface type is unchanged.
Closes #494
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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const c: C = { x: 3, f() { return 2; } }compiled, but the instance was wrong. An object literal with a method or an accessor is boxed (an!ts.object), and its cast to the class was a plaints.Castof the pointer, so no instance was built:c.xread the class's field slot out of memory laid out as{x, f}, which gave garbage such as1.34e-311.c.f()called through a vtable that wasn't there, which crashed with 0xC0000005.A class instance takes its methods from its class's vtable, so one object cannot have a method of its own. In TypeScript
c.f()would give 2; tslang has no way to express that. As agreed, such a literal is now a compile error wherever it meets a class type (a declaration, a parameter, a return, oras C):A literal with fields only is still made into an instance (#487). A literal with methods assigned to an interface type is unchanged: it prints
3 2under gc, rc, none and own.New tests:
object-literal-to-class/{method,accessor,parameter,return}.tsexpect the error. Onmainthese files compile with no error.weakref_basicis gc-only, as onmain)Closes #494
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