Invalid llvm ir for blockarg generated when a cast is applied to the result of an auto

[dgrove-oss]

The test program below is extracted from NetNative.getIntOption0. When compiled with qbicc it generates invalid llvm ir (type mismatch).

import static org.qbicc.runtime.CNative.*;
import static org.qbicc.runtime.posix.SysSocket.*;

import java.io.IOException;
import java.net.SocketException;

class PointerBlockTest {

    public static void main(String[] args) {
        getIntOption0(1, 1, true);
    }

    static int opaque(socklen_t x) {
        return 0;
    }
    
    private static int getIntOption0(int level, int opt, boolean flag) {
        c_int result = auto();
        struct_linger linger = auto();
        socklen_t arglen = auto(sizeof(result)).cast();

        if (flag) {
            arglen = sizeof(linger).cast();
        }

        return opaque(arglen);
    }
}

The llc error:

 <stdin>:86:9: error: stored value and pointer type do not match
  store i32 8, i64* %bb1.20, align 8, !dbg !836 ; PointerBlockTest.java:25 bci@48

This store corresponds to the conditional assignment of arglen inside the if.

[dgrove-oss]

And in the clear light of a small test case, I realized that one could (should?) instead write:

        socklen_t arglen = auto(sizeof(result).cast(socklen_t.class));

This compiles just fine and generates valid llvm ir.

[dgrove-oss]

So maybe the only issue here is that it would have been nice to flag the casting of the result of auto as an error since it resulted in a size-mismatch between the nominal type of the local variable and the size of the backing storage associated with it.