Compiler Prediction Error

[KoromaruKoruko]

General

Version : 3.1
VisualStudio: 2019 16.5.4

public Boolean TryTest(String X, out String Y)
{
    Lazy<Dictionary<String, String>> A, B;
    if (A.IsValueCreated ? A.Value.TryGetValue(X, out Y) : false
        || B.IsValueCreated ? B.Value.TryGetValue(X, out Y) : false)
        return true
    Y = null;
    return false
}

is the same as

public Boolean TryTest(String X, out String Y)
{
    Lazy<Dictionary<String, String>> A, B;
    if (A.IsValueCreated && A.Value.TryGetValue(X, out Y)
        || B.IsValueCreated && B.Value.TryGetValue(X, out Y))
        return true
    Y = null;
    return false
}

the above snippet works with no issue but the first one will throw a compile error stating that Y would not be set by the if-statements return.

this has no real implications with this example as using && is by far much better then using ? : but as it stands it is an error in the compilers ability to predict and as such should be fixed as it may have some other unforeseen implication in another project.

[RikkiGibson]

This feature request requires that we amend the definite assignment specification. Therefore moving to csharplang.

[333fred]

This is very similar to #3365.

[ntovas]

Maybe the compiler don't analyze the A.Value.TryGetValue(X, out Y) in respect to the if statements context? And most importantly, should it?

[KoromaruKoruko]

it is the exact same as reported in #3365 so ignore this thread, and move to that one.