4 ms·

Structs are values and you can return them like any value (or use them as parameters). I'm not sure what you mean about compilers.

by juped 7y ago

teddyh 7y ago
See, for instance, here: https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Incompatibilities.html#index-structures https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Incompatibiliti... https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Code-Gen-Options.html#index-fpcc-struct-return https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Code-Gen-Option... https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Warning-Options.html#index-Waggregate-return https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Warning-Options...
- juped 7y ago
  Oh, I get it. This is mostly not a practically relevant issue. (Nor are pre-K&R compilers relevant, although something like this could arise among modern compilers.) As far as oddball situations go, it's far from the thorniest to deal with - it doesn't even involve C++.
JdeBP 7y ago
Xe is conflating compilers and calling conventions a bit. The way that structure types are returned varies by calling convention, as indeed do a lot of other things. Mismatched calling conventions leads to problems. But structure type return values are well specified for most calling conventions, and quite a number of compilers support explicitly specifying the calling convention for mixed-language or mixed-compiler situations. * http://jdebp.uk./FGA/function-calling-conventions.html http://jdebp.uk./FGA/function-calling-conventions.html
- teddyh 7y ago
  Many calling conventions apparently use a method for returning structs which is inherently non-thread-safe. Also from that link: > 32-bit cdecl calling convention > For return values of structure or class type, there is wide incompatibility amongst compilers. Some make the return thread-safe, by breaking compatibility with the 16-bit cdecl calling convention. Some retain compatibility, at the expense of their 32-bit cdecl calling convention not being thread-safe. The ones that break compatibility don't all agree with one another on how to do so.

Structs are values and you can return them like any value (or use them as parameters). I'm not sure what you mean about compilers.

by juped 7y ago

Structs are values and you can return them like any value (or use them as parameters). I'm not sure what you mean about compilers.

teddyh 7y ago

See, for instance, here: https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Incompatibilities.html#index-structures https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Incompatibiliti... https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Code-Gen-Options.html#index-fpcc-struct-return https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Code-Gen-Option... https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Warning-Options.html#index-Waggregate-return https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Warning-Options...

juped 7y ago
Oh, I get it. This is mostly not a practically relevant issue. (Nor are pre-K&R compilers relevant, although something like this could arise among modern compilers.) As far as oddball situations go, it's far from the thorniest to deal with - it doesn't even involve C++.

JdeBP 7y ago

Xe is conflating compilers and calling conventions a bit. The way that structure types are returned varies by calling convention, as indeed do a lot of other things. Mismatched calling conventions leads to problems. But structure type return values are well specified for most calling conventions, and quite a number of compilers support explicitly specifying the calling convention for mixed-language or mixed-compiler situations. * http://jdebp.uk./FGA/function-calling-conventions.html http://jdebp.uk./FGA/function-calling-conventions.html

teddyh 7y ago
Many calling conventions apparently use a method for returning structs which is inherently non-thread-safe. Also from that link: > 32-bit cdecl calling convention > For return values of structure or class type, there is wide incompatibility amongst compilers. Some make the return thread-safe, by breaking compatibility with the 16-bit cdecl calling convention. Some retain compatibility, at the expense of their 32-bit cdecl calling convention not being thread-safe. The ones that break compatibility don't all agree with one another on how to do so.