CODEWITHSUNDEEP
c++gcc
Thomas
Thomas

Reputation: 4255

What order does gcc __attribute__((constructor)) run in relation to global variables in same translation unit?

I saw this question answering some of this, but at least not clearly my question.

I suspect that I should probably not access any global variables that requires code to execute (e.g. std::string), but how about POD variables?

std::string s = "hello";
const char* c = "world";
extern std::string s2; // (actually below in the same TU)
__attribute__((constructor)) void init()
{
   // safe to assume that !strcmp(c, "world");
   // not safe to assume s == "hello"?
   // even less safe to assume s2 == "foo";
}

std::string s2 = "foo";

Upvotes: 0

Views: 338

Answers (1)

eerorika
eerorika

Reputation: 238351

The documentation says:

However, at present, the order in which constructors for C++ objects with static storage duration and functions decorated with attribute constructor are invoked is unspecified.

!strcmp(c, "world") is probably safe to assume.

char* c = "world";

This is ill-formed because string literal doesn't implicitly convert to a pointer to non-const char (since C++11).

Upvotes: 3

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