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Call arity checks; C variadic (@varargs) functions callable through values and across modules - #604
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`new C().m(1, 2, 3)` for a two-parameter method compiled silently: the
third operand went into a slot the callee does not have. It is now
TS2554 ("Expected 2 arguments, but got 3."), checked in checkCallArity
for every call mlirGenCallFunction builds (functions, methods,
constructors, closures, `?.` calls, @cpp vtable methods).
A rest parameter takes any number of arguments, and so does a C
variadic function declared `@varargs declare function f(n: s32)`
(tsbindgen writes them so), whose extra arguments go to C's `...`. Its
function type does not say so, only the decorator, so isCVarArgCall
reads that. A @cpp method's hidden result slot is not counted in the
message.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
`@varargs declare function printf(format: string)` put `func.varargs` on
the function only, so its type did not say it was variadic. A call by name
worked; `let p = printf; p("%f\n", 1.5)` or a `typeof printf` parameter
lowered as a fixed-arity indirect call (a double printed 0.000000 on
Win64), and since the arity check it was "Expected 1 arguments, but got 2."
!ts.func gets an isCVarArg parameter (printed only when set), set on the
type of a @VarArgs function in mlirGenFunctionPrototype. typeof and
assignment keep it; a `let` holding one stays a plain function, not a
hybrid one (it captures nothing). checkCallArity reads it from the callee
type, replacing isCVarArgCall's symbol lookup. An indirect call or invoke
of such a type gets var_callee_type, so LLVM passes the extra arguments the
C variadic way. A C variadic function type and a plain one do not cast to
each other.
The arguments to `...` get C's default promotions, on every call: an f32
went as a float and printed 0.000000 even when printf was called by name.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The previous commit made `let p = printf` and a `typeof printf` parameter variadic calls; a @VarArgs function held elsewhere or exported still was not. A C variadic type now has a spelling, `CVarArgs<(format: string) => s32>`, which the printer writes for it, so __decls declares an exported `let cprintf = printf` (and a parameter or field of that type) as one and importers call it the C variadic way. Such a value is always one pointer, as in C: CVarArgs<arrow> is a plain function, not a hybrid one, and an exported global holding one is not widened, so library and importer store it alike. An object-type field of that type prints as a value, not as a method signature. !ts.hybrid_func carries the flag as well (from the function it is made from), and a call of a C variadic hybrid value is a variadic call. mergeFuncTypes keeps it and finds no common type for a C variadic and a TypeScript function. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Summary
Three commits:
?.calls and @cpp vtable methods. A rest parameter and a C variadic (@varargs) callee take any number of arguments.!ts.funcgets anisCVarArgflag, printed only when set. It is set on the type of a@varargsfunction and kept bytypeofand assignment.let p = printf; p("%f\n", 1.5)and atypeof printfparameter used to lower as fixed-arity calls, which printed 0.000000 on Win64; since the arity check they were rejected. Indirect calls and invokes of a flagged type now setvar_callee_type. A C variadic function type and a plain one no longer cast to each other. Extra arguments get C's default promotions on every call, including by name: anf32printed 0.000000 even throughprintf(...).CVarArgs<(format: string) => s32>is the source spelling of a C variadic type. The printer writes it, so__declsround-trips an exportedlet cprintf = printf, parameter or field. Such a value is always one pointer, never widened to a hybrid one.!ts.hybrid_funccarries the flag too, andmergeFuncTypesfinds no common type for mixed flags.CVarArgsis now a reserved built-in type name, likeShared.Tests
call-arity/: too-many-arguments cases for each call kind, including a non-variadic function value and parameter.c-varargs/value_call.ts(JIT): calls by name, throughletand through a parameter, mixed int/double arguments, and promotions; expects1.500000. It also prints correctly as an AOT exe.c-varargs/to_plain.ts,from_plain.ts: the cast is rejected both ways.00funcs_c_varargs_storage.ts: class field, constructor-parameter field, object member, optional value andCVarArgsannotation; runs under the default, rc and none models.import_c_varargs.ts/export_c_varargs.ts: static,-shared, and JIT-shared.Windows Release ctest: 0 failures out of 4188.
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