New warning on macOS

[certik]

/Users/ondrej/repos/lpython/src/libasr/codegen/llvm_utils.cpp:1487:21: warning: variable 'pred' is used uninitialized whenever switch default is taken [-Wsometimes-uninitialized]
                    default: {
                    ^~~~~~~
/Users/ondrej/repos/lpython/src/libasr/codegen/llvm_utils.cpp:1491:43: note: uninitialized use occurs here
                return builder->CreateCmp(pred, left, right);
                                          ^~~~
/Users/ondrej/repos/lpython/src/libasr/codegen/llvm_utils.cpp:1465:9: note: variable 'pred' is declared here
        llvm::CmpInst::Predicate pred;
        ^

I thought we test for this at the CI. Maybe we only do it for LFortran.

[ubaidsk]

I thought we test for this at the CI. Maybe we only do it for LFortran.

Yes, we have to add -Werror at the CI. We previously discussed it here #2062 (review). I have a minor concern. When building lpython there is warning about unused variable yynerrs in parser.tab.cc. This file parser.tab.cc is a generated file, thus we are unable to use the variable or add maybe unused. We do not experience this in lfortran since it uses %glr-parser, where as (it seems) lpython uses LR(1) parser.

The warning of unused variable yynerrs in parser.tab.cc seems to be a bug in bison. This bug seems to be fixed in the latest bison, but they did not make a release of it post fixing. I have requested for a release here akimd/bison#103.

[certik]

There might be a way to turn off -Werror for the Bison file. Alternatively we can "post process" the file to remove "yynerrs" with a Python script.