[Lazarus] Question about static linking problem

[Anthony Walter]

Problem: Certain object files cannot be placed in an archive file (a static
library) and referenced with {$linklib myarchive} is a pascal unit. I don't
know why and would like some advice.

I am attempting to link a static library (an archive of object files) built
on Linux using mingw-w64 for Windows target and have a problem and a
question. I've built the static library libSDL2.a (also known as an archive
of object files) and dynamic library libSDL2.dll for Windows using the
mingw-w64 compiler on Linux fine. Previously I've been linking to the
dynamic library on Windows without problems, but now I want the option to
compile using the static library.

Putting {$linklib SDL2} in my package source code causes a few unresolved
references when attempting to compile an application.

Examples:

> Error: Undefined symbol: _strdup
> Error: Undefined symbol: _itoa
> Error: Undefined symbol: ___divdi3
> Error: Undefined symbol: ___udivdi3

I can resolve these missing symbols using nm to search object and archive
files in the /usr/i686-w64-mingw32/lib/:

> i686-w64-mingw32-nm -o *.a | grep udivdi3

One by one I find all the missing symbols and copy the archive containing
what's missing to a folder inside my package directory and adding an
additional {$linklib foundarchive} to my sources. This works fine.

The problem is certain archives or object files refuse to work with this
technique.

Both ___divdi3 and ___udivdi3 are in the i686-w64-mingw32 libgcc.a archive.

I can extract the object files _divdi3.o and _udivdi3.o which contain the
missing functions from libgcc.a using i686-w64-mingw32-ar x libgcc.a
_divdi3.o and _udivdi3.o.

I can link these two object files in my source code using {$l
/path/to/files/_divdi3.o} and {$l /path/to/files/_udivdi3.o} and everything
compiles okay and the programs run great.

I can even insert _divdi3.o into libSDL2.a and remove {$l
/path/to/files/_divdi3.o} from my source. But there is problem is with
_udivdi3.o.

For whatever reason if I put _udivdi3.o into an archive, such as libSDL2.a,
or if I create an archive with just that file in it, such as

> i686-w64-mingw32-ar rcs libudivdi3.a _udivdi3.o

I still cannot use {$linklib udivdi3}. When I attempt to build I still get:

> Error: Undefined symbol: ___udivdi3

It's only by using code like {$l /path/to/files/_udivdi3.o} that I can get
fpc to see the missing symbol ___udivdi3. This presents a problem because I
must use the full path to _udivdi3.o (mind you my sources are in a
package). If I want other people to reuse my package this presents a
problem, as their paths may differ from mine.

What I'd really like is to find out how I can place _udivdi3.o inside a
archive and get fpc to resolve ___udivdi3 when {$linklib myarchive} or
{$linklib SDL2} is used.
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