Given -r, emcc sill requests to use -r for object file extensions

[zauguin]

Please include the following in your bug report:

Version of emscripten/emsdk:

emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.0.0-git (3fd52e107187b8a169bb04a02b9f982c8a075205)`

(This is the Arch Linux package. Not sure why it's claiming to be a git version, but it builds the 3.0.0 tag with no changes to the source code)

Failing command line in full:

% touch empty{1,2}.cpp
% emcc -r empty{1,2}.cpp -o empty.o
emcc: warning: generating an executable with an object extension (.o).  If you meant to build an object file please use `-c, `-r`, or `-shared` [-Wemcc]

The warning seems wrong: It explicitly tells me to use -r if I want an object file, but I already do use that option.

Full command and output with -v appended:

% emcc -r empty{1,2}.cpp -o empty.o -v
"/opt/emscripten-llvm/bin/clang++" -target wasm32-unknown-emscripten -DEMSCRIPTEN -fignore-exceptions -fvisibility=default -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr -D__EMSCRIPTEN_major__=3 -D__EMSCRIPTEN_minor__=0 -D__EMSCRIPTEN_tiny__=0 -D_LIBCPP_ABI_VERSION=2 -Werror=implicit-function-declaration -Xclang -iwithsysroot/include/SDL --sysroot=/home/marcel/.emscripten_cache/sysroot -Xclang -iwithsysroot/include/compat -v empty1.cpp -c -o /tmp/emscripten_temp_mkvix7eg/empty1_0.o
clang version 14.0.0 (/srcdest/llvm-project 4348cd42c385e71b63e5da7e492172cff6a79d7b)
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: /opt/emscripten-llvm/bin
 (in-process)
 "/opt/emscripten-llvm/bin/clang-14" -cc1 -triple wasm32-unknown-emscripten -emit-obj -mrelax-all --mrelax-relocations -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name empty1.cpp -mrelocation-model static -mframe-pointer=none -ffp-contract=on -fno-rounding-math -mconstructor-aliases -target-cpu generic -debugger-tuning=gdb -v -fcoverage-compilation-dir=/home/marcel/cppexper/emsc -resource-dir /opt/emscripten-llvm/lib/clang/14.0.0 -D EMSCRIPTEN -D __EMSCRIPTEN_major__=3 -D __EMSCRIPTEN_minor__=0 -D __EMSCRIPTEN_tiny__=0 -D _LIBCPP_ABI_VERSION=2 -isysroot /home/marcel/.emscripten_cache/sysroot -internal-isystem /home/marcel/.emscripten_cache/sysroot/include/wasm32-emscripten/c++/v1 -internal-isystem /home/marcel/.emscripten_cache/sysroot/include/c++/v1 -internal-isystem /opt/emscripten-llvm/lib/clang/14.0.0/include -internal-isystem /home/marcel/.emscripten_cache/sysroot/include/wasm32-emscripten -internal-isystem /home/marcel/.emscripten_cache/sysroot/include -Werror=implicit-function-declaration -fdeprecated-macro -fdebug-compilation-dir=/home/marcel/cppexper/emsc -ferror-limit 19 -fvisibility default -fgnuc-version=4.2.1 -fcxx-exceptions -fignore-exceptions -fexceptions -fcolor-diagnostics -iwithsysroot/include/SDL -iwithsysroot/include/compat -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr -o /tmp/emscripten_temp_mkvix7eg/empty1_0.o -x c++ empty1.cpp
clang -cc1 version 14.0.0 based upon LLVM 14.0.0git default target x86_64-unknown-linux-gnu
ignoring nonexistent directory "/home/marcel/.emscripten_cache/sysroot/include/wasm32-emscripten/c++/v1"
ignoring nonexistent directory "/home/marcel/.emscripten_cache/sysroot/include/wasm32-emscripten"
#include "..." search starts here:
#include <...> search starts here:
 /home/marcel/.emscripten_cache/sysroot/include/SDL
 /home/marcel/.emscripten_cache/sysroot/include/compat
 /home/marcel/.emscripten_cache/sysroot/include/c++/v1
 /opt/emscripten-llvm/lib/clang/14.0.0/include
 /home/marcel/.emscripten_cache/sysroot/include
End of search list.
 "/opt/emscripten-llvm/bin/clang++" -target wasm32-unknown-emscripten -DEMSCRIPTEN -fignore-exceptions -fvisibility=default -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr -D__EMSCRIPTEN_major__=3 -D__EMSCRIPTEN_minor__=0 -D__EMSCRIPTEN_tiny__=0 -D_LIBCPP_ABI_VERSION=2 -Werror=implicit-function-declaration -Xclang -iwithsysroot/include/SDL --sysroot=/home/marcel/.emscripten_cache/sysroot -Xclang -iwithsysroot/include/compat -v empty2.cpp -c -o /tmp/emscripten_temp_mkvix7eg/empty2_1.o
clang version 14.0.0 (/srcdest/llvm-project 4348cd42c385e71b63e5da7e492172cff6a79d7b)
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: /opt/emscripten-llvm/bin
 (in-process)
 "/opt/emscripten-llvm/bin/clang-14" -cc1 -triple wasm32-unknown-emscripten -emit-obj -mrelax-all --mrelax-relocations -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name empty2.cpp -mrelocation-model static -mframe-pointer=none -ffp-contract=on -fno-rounding-math -mconstructor-aliases -target-cpu generic -debugger-tuning=gdb -v -fcoverage-compilation-dir=/home/marcel/cppexper/emsc -resource-dir /opt/emscripten-llvm/lib/clang/14.0.0 -D EMSCRIPTEN -D __EMSCRIPTEN_major__=3 -D __EMSCRIPTEN_minor__=0 -D __EMSCRIPTEN_tiny__=0 -D _LIBCPP_ABI_VERSION=2 -isysroot /home/marcel/.emscripten_cache/sysroot -internal-isystem /home/marcel/.emscripten_cache/sysroot/include/wasm32-emscripten/c++/v1 -internal-isystem /home/marcel/.emscripten_cache/sysroot/include/c++/v1 -internal-isystem /opt/emscripten-llvm/lib/clang/14.0.0/include -internal-isystem /home/marcel/.emscripten_cache/sysroot/include/wasm32-emscripten -internal-isystem /home/marcel/.emscripten_cache/sysroot/include -Werror=implicit-function-declaration -fdeprecated-macro -fdebug-compilation-dir=/home/marcel/cppexper/emsc -ferror-limit 19 -fvisibility default -fgnuc-version=4.2.1 -fcxx-exceptions -fignore-exceptions -fexceptions -fcolor-diagnostics -iwithsysroot/include/SDL -iwithsysroot/include/compat -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr -o /tmp/emscripten_temp_mkvix7eg/empty2_1.o -x c++ empty2.cpp
clang -cc1 version 14.0.0 based upon LLVM 14.0.0git default target x86_64-unknown-linux-gnu
ignoring nonexistent directory "/home/marcel/.emscripten_cache/sysroot/include/wasm32-emscripten/c++/v1"
ignoring nonexistent directory "/home/marcel/.emscripten_cache/sysroot/include/wasm32-emscripten"
#include "..." search starts here:
#include <...> search starts here:
 /home/marcel/.emscripten_cache/sysroot/include/SDL
 /home/marcel/.emscripten_cache/sysroot/include/compat
 /home/marcel/.emscripten_cache/sysroot/include/c++/v1
 /opt/emscripten-llvm/lib/clang/14.0.0/include
 /home/marcel/.emscripten_cache/sysroot/include
End of search list.
emcc: warning: generating an executable with an object extension (.o).  If you meant to build an object file please use `-c, `-r`, or `-shared` [-Wemcc]
 "/opt/emscripten-llvm/bin/wasm-ld" -o empty.o /tmp/emscripten_temp_mkvix7eg/empty1_0.o /tmp/emscripten_temp_mkvix7eg/empty2_1.o -L/home/marcel/.emscripten_cache/sysroot/lib/wasm32-emscripten --relocatable -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr

[sbc100]

Sorry, yes, I think that is an erroneous warning. I'll see if I can upload a patch now.

BTW, what is your use case for using the -r option? Would using emar archives work for you?

[zauguin]

BTW, what is your use case for using the -r option? Would using emar archives work for you?

I tried to make some project which didn't get updated in a while compile again which relied on -r as default behavior, so the first approach was to add it explicitly. I don't think that there is any real reason why archives aren't used here.

[sbc100]

If you can move away from using emcc -r that would be great. In particular we hope to remove the "combine bitcode using llvm-link" part of it a some point: #15724 (This mostly effects folks who are doing LTO)