Getting function argument types

Question

Suppose I have a call to a function which takes a variable number of arguments in my source code. I want to do some kind of static analysis on this source code to find the type of the arguments being actually passed to the function. For example, if my function call is -

foo(a, b, c)

I want to find the data type of a, b and c and store this information.

FWIW if your function is a `printf`- or `scanf`-like variant, and if you're using gcc, you can use [`format` function attribute](http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#index-g_t_0040code_007bformat_007d-function-attribute-2417) with your function, and the compiler will automatically type-check your arguments to all calls of that function. — Adam Rosenfield, Jun 23 '11 at 02:46

dmckee --- ex-moderator kitten · Answer 1 · 2011-06-23T02:48:41.213

1

You pretty well have to do the parse-and-build-a-symbol-table part of compiling the program.

Which means running the preprocessor, and lexing as well.

That's the bad news.

The good news is that you don't have to do much of the hard stuff. No need to build a AST, every part of the code except typedefs; struct, union, and enum definitions; variable-or-function declarations-and-definitions; and analyzing the function call arguments can be a no-op.

On further thought prompted by Chris' comments: You do have to be able to analyze the types of expressions and handle the va-arg promotions, as well.

It is still a smaller project than writing a whole compiler, but should be approached with some thought.

edited Jun 23 '11 at 02:48

answered Jun 23 '11 at 02:38

dmckee --- ex-moderator kitten

98,632
24
142
234

You don't even need definitions - `struct` declarations are all you need. You can discard the definitions. – Chris Lutz Jun 23 '11 at 02:43
@Chris, unless the call looks like `foo(bar.i)`, no? – dmckee --- ex-moderator kitten Jun 23 '11 at 02:44
Also, yu'd have to be really careful about the types of literals, especially after promotions from variadic functions. And I suppose you'd need to parse most expressions. – Chris Lutz Jun 23 '11 at 02:45
@Chris: Yeah. Yeah, there is that. The more I think about it, the less noopy the whole thing looks. You have to analyze expression types---or at least be able to analyze expression types. – dmckee --- ex-moderator kitten Jun 23 '11 at 02:47

score 0 · Answer 2 · answered Nov 27 '10 at 07:05

0

If this is in C++, you can hack together some RTTI using typeid etc.

http://en.wikipedia.org/wiki/Run-time_type_information

answered Nov 27 '10 at 07:05

Hank

547
3
4

1

Resisted my knee-jerk "downvote everyone who mentions C++ in a C question" long enough to check that the language was added as an afterthought rather than part of the question. – Chris Lutz Jun 23 '11 at 02:41

Getting function argument types

2 Answers2

Linked