On Friday, 10 August 2018 at 08:31:21 UTC, learnfirst1 wrote:
#!/usr/bin/env rdmd
import core.stdc.stdio;
template G(size_t line = __LINE__, A...){
int i = 3;
static extern(C) pragma(crt_constructor) void init2(){
printf("init: %d\n", line);
}
}
pragma(crt_constructor) extern(C) void init1(){
printf("init from global\n");
}
struct A {
mixin G!();
}
extern(C) void main(){
mixin G!() g;
printf("g.i=%d\n", g.i);
g.init2(); // remove this can build, but g.init2 not get
called!
}
-----------------
build error:
Undefined symbols for architecture x86_64:
"__D4test4mainUZ1g5init2UNbNiZv", referenced from:
It is indeed. Reduced example:
template G(){
extern(C) pragma(crt_constructor) void init(){}
}
void main(){
mixin G!();
init();
}
For nested functions, extern(C) is simply ignored[0]. Since
pragma(crt_constructor) requires that the symbol it's applied to
uses C linkage (and an error message to that effect is shown if
you write pragma(crt_constructor) void fun() {} in module scope:
Error: function `fun` must be extern(C) for
pragma(crt_constructor)
In addition, if you try to apply pragma(crt_constructor) to a
nested function, you get this error message, showing further that
nested functions can't be crt_constructors:
Error: unrecognized pragma(crt_constructor)
The correct behavior would be for the compiler to show the latter
error message for a mixin'd function as well.
Filed a bug:
https://issues.dlang.org/show_bug.cgi?id=19153
--
Simen
[0]: from https://dlang.org/spec/attribute.html#linkage:
Note that extern(C) can be provided for all types of
declarations, including struct or class, even though there is no
corresponding match on the C side. In that case, the attribute is
ignored. This behavior applies for nested functions and nested
variables as well.
