Bug 23061 – Exceptions cannot be caught by catch statement in static build

Exceptions cannot be caught in the static linked configuration but they should be caught. In the dynamic linked configuration, they can be caught as intended. I first filed it in ldc but finally I found it is a issue in druntime. - https://github.com/ldc-developers/ldc/issues/3965 # Reproduced versions I checked this issue with the following environment with Docker container. - dmd 2.098.0-r0 in Alpine Linux 3.15 - ldc 1.28.0-r0 in Alpine Linux 3.15 - ldc 1.28.1-r0 in Alpine Linux edge # How to reproduce app.d: ```dlang void main(string[] args) { try { throw new Exception("aaa"); } catch(Exception e) { } } ``` Compile and execute it in Alpine Linux image as follows: ```console $ docker run --rm -it -v $PWD:/workdir -w /workdir alpine:3.15 sh # apk --no-cache add dmd gcc musl-dev llvm-libunwind-static # dmd -c app.d # gcc -static app.o -o app -lphobos2 -lunwind # ldd app /lib/ld-musl-x86_64.so.1: app: Not a valid dynamic program # ./app ``` # Expected behavior It can be executed without errors. # Actual behavior It fails execution with the exception message. ```console # ./app src/rt/dwarfeh.d:330: uncaught exception reached top of stack This might happen if you're missing a top level catch in your fiber or signal handler [email protected](11): aaa ---------------- ??:? <ERROR: Unable to retrieve function name> [0x0] Aborted ``` Note that it can successfully be executed when I compile it with `dmd app.d`. --- I reproduce the same issue with ldc as the following instructions: ```console $ docker run --rm -it -v $PWD:/workdir -w /workdir alpine:3.15 sh # apk --no-cache add ldc gcc musl-dev llvm-libunwind-static # ldc2 -static app.d # ./app rt/dwarfeh.d:354: uncaught exception reached top of stack This might happen if you're missing a top level catch in your fiber or signal handler [email protected](11): aaa ---------------- src/ctype/isspace.c:10 <ERROR: Unable to retrieve function name> [0x0] Aborted ```

I changed the severity to `major` because it prevents from using exception, that is a language feature of D.

I found that this issue only happens when dmd is built with `DRuntime_Use_Libunwind`. I built dmd with `DRuntime_Use_Libunwind` on Alpine Linux edge and obtained the following results. When `app.d` is built without `-lunwind`, it works as intended as follows: ```console $ ./dmd/generated/linux/release/64/dmd -c app.d $ cc app.o -o app -m64 -static -Xlinker --export-dynamic -L./dmd/generated/linux/release/64/../../../../../phobos/generated/linux/release/64 -Xlinker -Bstatic -lphobos2 -lpthread -lm -lrt -ldl $ ./app $ echo $? 0 ``` On the other hand, when it is built with `-lunwind`, it does not work as reported. ```console $ ./dmd/generated/linux/release/64/dmd -c app.d $ cc app.o -o app -m64 -static -Xlinker --export-dynamic -L./dmd/generated/linux/release/64/../../../../../phobos/generated/linux/release/64 -Xlinker -Bstatic -lphobos2 -lpthread -lm -lrt -ldl -lunwind $ ./app src/rt/dwarfeh.d:330: uncaught exception reached top of stack This might happen if you're missing a top level catch in your fiber or signal handler [email protected](5): aa Aborted $ echo $? 134 ```

I close this issue because it is a matter of linker options rather than druntime itself. It only happens when using `gcc` on Alpine Linux. It does not happen when using `clang`. When we use `gcc` as a linker, it needs `-Xlinker --eh-frame-hdr`. ```console $ dmd -c app.d $ gcc app.o -o app -m64 -static -Xlinker --eh-frame-hdr -Xlinker --export-dynamic -L/usr/lib/ -Xlinker -Bstatic -lphobos2 -lpthread -lm -lrt -ldl -lunwind $ echo $? 0 ``` When we use `clang` as a linker, it works without `-Xlinker --eh-frame-hdr` because `clang` implicitly passes them to `ld`. ```console $ dmd -c app.d $ clang app.o -o app -m64 -static -Xlinker --export-dynamic -L/usr/lib/ -Xlinker -Bstatic -lphobos2 -lpthread -lm -lrt -ldl -lunwind $ ./app $ echo $? 0 ```