[ICE] reached unreachable: bug in const_fold or parser

[Byter09]

Expected behavior

Possibly an error? Not sure.

Actual Behavior

The application panicked (crashed).
Message:  internal error: entered unreachable code: bug in const_fold or parser: cpp cond should be boolean
Location: src/lex/cpp.rs:605

Code

#if!F?"":!a

Backtrace

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ BACKTRACE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
                          (5 post panic frames hidden)                          
 5: rcc::lex::cpp::PreProcessor::boolean_expr::hb14924dc1e2aa075
    at src/lex/cpp.rs:605
 6: rcc::lex::cpp::PreProcessor::directive::h1d36c2bd1020b8e4
    at src/lex/cpp.rs:395
 7: <rcc::lex::cpp::PreProcessor as core::iter::traits::iterator::Iterator>::next::hfca8c81831b50c63
    at src/lex/cpp.rs:136
 8: rcc::compile::h53a76de88b04a7fa
    at src/lib.rs:156
 9: rcc::real_main::hae5b7d98d318c138
    at src/main.rs:109
10: rcc::main::h4220d37df2ab27ea
    at src/main.rs:176

File, fresh from the fuzzer:

SIGABRT.PC.7ffff7dee7bb.STACK.b8fd143c.CODE.-6.ADDR.(nil).INSTR.mov____0x108(%rsp),%rcx.tar.gz

[jyn514]

This should be an error, string literals are not allowed in preprocessing expressions.

$ run_clang
#if!F?"":!a
#endif     
int main() {}
<stdin>:1:7: error: invalid token at start of a preprocessor expression
#if!F?"":!a
      ^

[jyn514]

Whoops, linked the wrong issue.

[jyn514]

Hmm, this is actually a bug in the constant folder, it's returning (Str([0]), Bool), but it should always return an Int if it returns a boolean type.

[jyn514]

Actually I think the issue is in logical_not, which really mangles this expression:

expr is (((0) != ((long)(0))) == ((_Bool)(0))) ? ("") : (((0) != ((long)(0))) == ((_Bool)(0)))
truthy expr is (((0) != ((long)(0))) == ((_Bool)(0))) ? ("") : (((0) != ((long)(0))) == ((_Bool)(0)))