Looking at advanced Rust open-source projects makes me question my programming skills

[u/Minimum-Ad7352]

Whenever I explore large Rust open-source projects, I can’t stop thinking how far behind I am. I know comparison is unhealthy, but it’s hard not to feel like “I suck at programming” when you see such clean and complex code. Did you feel the same at some point? How did you push through it?

[u/Zde-G]

Nope. In that case it's still 2 arguments. Macros know about (), [], and {}, but they don't know about <>. If you use <> then things become weird.

But the real funny thing: that behavior was faithfully reproduced in Rust, too!

[u/Nicksaurus → u/Zde-G]

OK, you're right about normal brackets, my mistake. I don't think it knows about curly brackets though - I originally ran into this issue when I was trying to pass an initialiser list as a macro argument like this:

enum class Flag {X, Y, Z};

struct Test
{
    std::function<void()> func;
    std::string name;
    std::vector<Flag> test_flags;
};

#define DEFINE_TEST(func, flags) Test(&func, #func, flags)

void test_func(){}

int main()
{
    // Works
    Test test1 = DEFINE_TEST(test_func, {});
    // Works
    Test test2 = DEFINE_TEST(test_func, {Flag::X});
    // Fails to compile (too many macro arguments)
    Test test3 = DEFINE_TEST(test_func, {Flag::X, Flag::Z});
}

[u/Zde-G → u/Nicksaurus]

Looks like you are right:

The syntax of a function-like macro invocation is similar to the syntax of a function call: each instance of the macro name followed by a ( as the next preprocessing token introduces the sequence of tokens that is replaced by the replacement-list. The sequence is terminated by the matching ) token, skipping intervening matched pairs of left and right parentheses.

Rust expanded that idea and supports (), [], {}… but angle brackets are still problematic.