[Issue 17969] New: dmd 2.077.0 crashes when computing mangling symbol for simple program

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=17969

          Issue ID: 17969
           Summary: dmd 2.077.0 crashes when computing mangling symbol for
                    simple program
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: critical
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: atila.neves at gmail.com

This code causes dmd 2.070.0 to crash:

void foo() {
    struct Data {
        double value;
    }
    oops([Data()]);
}


void oops(Data)(Data[] data) {
    import std.algorithm: map;
    auto values = [data].map!(a => a.map!(b => b.value).sum);
}

Earlier versions aren't affected. Notice that `sum` isn't imported. If it is,
the crash goes away. If `b.value` is replaced with `b.foo` (or any other name
that doesn't exist in the struct), it also crashes, so it seems to have to do
with the function failing to compile.

The stack trace points to
_ZN7Mangler14mangleFuncTypeEP12TypeFunctionS1_hP4Type.

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