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Type Resolution in Exception Handling

When an exception is thrown at C++and the stack is unwound, as shown in the correct handler (sentence catch) to handle the exception?

void f1()
{
    throw 1;
}

void f2()
{
    try
    {
        f1();
    }
    catch(const char* e)
    {
        std::cout << "exc1";
    }
}

...
try
{
    f2();
}
catch(int& e)
{
    std::cout << "exc2";
}
...

For example, this code unsurprisingly prints "exc2"because it catch(int& e)is capable of handling a typed object 1 int.

I do not understand how this can be solved statically? Or is it allowed dynamically? Is type information disseminated with exception?

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3 answers

As in most cases, the C ++ standard does not specify an implementation, but limits valid implementations. There will be no universal answer that knows about the specifics.

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+3

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+1

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:

https://godbolt.org/g/dyheBZ

(gcc) typeinfo .rodata , throw catch:

    .size   typeinfo for A, 16
typeinfo for A:
    .quad   vtable for __cxxabiv1::__class_type_info+16
    .quad   typeinfo name for A
    .weak   typeinfo name for A
    .section        .rodata._ZTS1A,"aG",@progbits,typeinfo name for A,comdat
    .type   typeinfo name for A, @object
    .size   typeinfo name for A, 3
typeinfo name for A:
    .string "1A"
    .text
    .type   __static_initialization_and_destruction_0(int, int), @function

throw A(); :

    mov     edi, 1
    call    __cxa_allocate_exception
    mov     edx, 0
    mov     esi, OFFSET FLAT:typeinfo for A
    mov     rdi, rax
    call    __cxa_throw
0

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