aaron.ballman added inline comments.
================
Comment at: lib/Sema/SemaDeclAttr.cpp:5305
+
+ if (hasFunctionProto(D) && getFunctionOrMethodNumParams(D) != 0) {
+ S.Diag(D->getLocation(), diag::warn_riscv_interrupt_attribute) << 0;
----------------
apazos wrote:
> aaron.ballman wrote:
> > I would have assumed this would be: `!hasFunctionProto(D) ||
> > getFunctionOrMethodNumParams(D) != 0`, but it depends on whether you want
> > to support K&R C functions.
> hasFunctionProto also returns true for a function definition like this one
> __attribute__((interrupt)) void foo1(int) {}.
That's correct, which is why I recommended the predicate the way I did. If the
function has no prototype, we want to diagnose it. If the function has a
prototype, we want to see how many parameters are listed and if there are more
than zero parameters, we want to diagnose it.
================
Comment at: test/Sema/riscv-interrupt-attr.c:23
+ // expected-note
{{repeated RISC-V 'interrupt' attribute is here}}
+__attribute__((interrupt("user"))) void foo8() {}
+__attribute__((interrupt("supervisor"))) void foo9() {}
----------------
apazos wrote:
> aaron.ballman wrote:
> > aaron.ballman wrote:
> > > Do you intend for functions without a prototype to be accepted? foo8()
> > > can be passed an arbitrary number of arguments, which is a bit different
> > > than what I thought you wanted the semantic check to be.
> > This question remains outstanding.
> The checks are validating both function definitions and function prototypes
> like these:
> _attribute__((interrupt)) void foo1() {}
> __attribute__((interrupt)) void foo(void);
> Not sure what the confusion is.
Ah, now I see where the confusion is.
In C, an empty parameter list declares a function without a prototype;
functions without prototypes can accept any number of arguments. To declare a
function that accepts no arguments, you must have a prototype for the function
and the parameter list is void. In C++, all functions are prototyped and an
empty parameter list is equivalent to a parameter list of void. The word
"prototype" doesn't mean "forward declaration". e.g.,
```
// C code
void foo1(); // Declaration; no prototype; accepts any number of arguments.
void foo2() {} // Definition; no prototype; accepts any number of arguments.
void foo3(void); // Declaration; prototype; accepts no arguments.
void foo4(void) {} // Definition; prototype; accepts no arguments.
foo2(1, 2, 3); // ok
foo4(1, 2, 3); // error
```
Because a function without a prototype can accept any number of arguments, I
think you want to diagnose such a function signature.
https://reviews.llvm.org/D48412
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