Impala fails parsing inline assembly with :::

[Richard Membarth]

Test case:

fn cuda_clock() -> u32 {
    let mut cycle_count:u32;
    asm("mov.u32 %0, %clock;" : "=r"(cycle_count) ::: "volatile");
    cycle_count
}

# > impala test.impala 
impala: anydsl/impala/src/impala/parser.cpp:1439: std::string impala::Parser::parse_str(): Assertion `false' failed.
Aborted (core dumped)

As a workaround, we can use : :: instead.