"Dead code" after a return

[asmeurer]

Is there a reason pyflakes doesn't warn on "dead code", i.e., code that cannot possibly be run because it comes after a return or a raise in the same block, like

def f():
    return
    g() # cannot be reached

I think return, raise, break, and continue are all such statements.

In a similar vein (should this be a separate issue?), what about unnecessary pass, like

if x:
    pass
    f()

Inline non-string literals or bare variable names might also fit into this category, although the latter can be a useful way to squash incorrect "unused variable" warnings.

[John Vandenberg (jayvdb)]

Also assignments preceding a return/raise, but not used in that branch.

def foo(a):
    if a:
        x = 10
        return a
    else:
        x = 20

    return x