clang -O0 and -O1 output differently

[shao-hua-li]

Hi there,

• Version: commit 90a63426ee93d9079a032740e519988e26d1949c (git head)
• Compiler: clang13

I compiled mujs with clang13 -O0 and clang13 -O1, for the following code snippets, mujs would output differently on stack {}:

-'a' + new String%Function
debugger

For clang13 -O0, the last value in stack {} is -nan, while for clang13 -O1, it's nan.

I'm pretty sure it's a compiler issue, so I tried to reduce mujs sourcecode. Interestingly, for the reduced source code, it triggered a gcc bug (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103406).