RFR: 8062808: Turn on the -Wreturn-type warning

[Kim Barrett]

On Nov 5, 2014, at 7:22 AM, Stefan Karlsson <stefan.karlsson at oracle.com> wrote:
> 
> Hi all,
> 
> I propose that we turn on the -Wreturn-type warning when compiling HotSpot with GCC.
> 
> This will help us catch missing return statements earlier in the development cycle.
> 
> http://cr.openjdk.java.net/~stefank/8062808/webrev.01/
> https://bugs.openjdk.java.net/browse/JDK-8062808

I’ve only skimmed this and not really reviewed, but I really dislike insertion of purportedly unreachable “return” statements to silence compiler warnings.  I have a similar dislike for “if (check for bad case) { non-returning error processing } /* no else */ …” to disable such warnings by avoid an apparent terminating control flow w/o return at the end of the error processing.  There’s got to be a better way…

I know that gcc/clang/MS all have annotation mechanism to mark code unreachable or functions as no-return.  I’d rather see something like that added and used before we turn on -Wreturn-type, rather than littering / contorting code to avoid that warning.  And compilers may generate better code sometimes when such are used.

And I say that having just last week wasted half a day debugging what turned out to be a small refactoring that left a code path without a return.