[cxx-abi-dev] lambda ABI inline function ODR compatibility issue

[Michael Wong]

Does the C++ Standard committee intend for the ODR to imply that lambdas
need to have an ABI specified layout in order to deal with inline
functions.

Consider the following with one object compiled with -DMAIN and another
without:
- in one case the layout needs to be compatible between different
implementations since the static local is shared between translation units

/data/a.o: In function `main':
a.cpp:(.text+0x18): undefined reference to `bar()'
collect2: error: ld returned 1 exit status

- in the other case, the layout needs to be compatible between different
implementations in order to satisfy the ODR requirement that the program
behave as if there was only one definition of the inline function

extern "C" int printf(const char *, ...);
extern long gz;

inline void foo() {
   long x = 0, q = 0, &z = gz;
   static auto f = [=, &z]() mutable { q += ++x; gz = q + x; };

   long a, b;
   auto ff = [=]{ sizeof(a /*not an odr-use*/), printf("%u\n", &b < &a); };
   f();
   ff();
}

void bar();

#if ! MAIN
void bar() { foo(); }
#else
long gz;
int main() {
   foo();
   bar();
   foo();
   return gz;
}
#endif

I apologize if this issue has been dealt with.

Regards, Michael

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