On Saturday 27 April 2024 22:47:33 LIU Hao wrote:
> The difference arises when building a DLL with this DEF file:
>
> * `foo = bar` (aliasing) indicates that a function called `bar` exists in
> the
> DLL's source code, and it is exported both as `foo` and `bar`. In the
> case of
> x86 stdcall, both `foo` and `bar` shall include an `@` suffix.
I did an another experiment for building a DLL library:
$ cat test.def
LIBRARY "test.dll"
EXPORTS
foo = bar
$ cat test.c
void bar(void) { }
$ i686-w64-mingw32-gcc -shared test.c test.def -o test.dll
$ readpe -e test.dll
Exported functions
Library
Name: test.dll
Functions
Function
Ordinal: 1
Address: 0x1410
Name: foo
So this shows that only symbol "foo" is exported. There is exported "bar".
> * `foo == bar` (renaming) indicates that a function called `foo` exists in
> the
> DLL's source code, and it is exported as `bar`. `bar` may and may not
> contain
> an `@` suffix, as the use varies.
Experiment:
$ cat test.def
LIBRARY "test.dll"
EXPORTS
foo == bar
$ cat test.c
void foo(void) { }
$ i686-w64-mingw32-gcc -shared test.c test.def -o test.dll
$ readpe -e test.dll
Exported functions
Library
Name: test.dll
Functions
Function
Ordinal: 1
Address: 0x1410
Name: bar
And there is only bar exported. When function is source code is named as
"bar" (like in the first example) then linker throws error:
i686-w64-mingw32-ld: cannot export foo: symbol not defined
collect2: error: ld returned 1 exit status
So based on these experiments when building library, I can conclude that:
X = Y
is the same as:
Y == X
and it means that function named X in the source code is present in the
result DLL library under name Y.
So `foo = bar` is also renaming of the symbol, and not aliasing.
For completeness, what happens when both = and == are used at the same line:
$ cat test.def
LIBRARY "test.dll"
EXPORTS
foo = func == bar
$ cat test.c
void func(void) { }
$ i686-w64-mingw32-gcc -shared test.c test.def -o test.dll
$ readpe -e test.dll
Exported functions
Library
Name: test.dll
Functions
Function
Ordinal: 1
Address: 0x1410
Name: bar
So line "X = Y == Z" has same meaning as "Y == Z" and so same as "Z = X".
Such logic does not make sense for me, but whatever. It shows that
documentation is incomplete and ambiguous.
_______________________________________________
Mingw-w64-public mailing list
Mingw-w64-public@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/mingw-w64-public
