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On Thu, Sep 13, 2018 at 4:13 PM Richard Yao <ryao@g.o> wrote: |
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> > On Sep 13, 2018, at 12:03 PM, Fabian Groffen <grobian@g.o> wrote: |
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> > |
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> >> On 13-09-2018 07:36:09 -0400, Richard Yao wrote: |
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> >> |
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> >> |
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> >>>> On Sep 12, 2018, at 6:55 PM, Thomas Deutschmann <whissi@g.o> wrote: |
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> >>>> |
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> >>>> On 2018-09-12 16:50, Rich Freeman wrote: |
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> >>>> There is also the case where we want these warnings to block |
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> >>>> installation, because the risk of there being a problem is too great. |
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> >>> |
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> >>> I really disagree with that. So many devs have already said multiple |
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> >>> times in this thread that "-Werror" is only turning existing warnings |
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> >>> into fatal errors but "-Werror" itself doesn't add any new checks and |
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> >>> more often requires "-O3" to be useful. |
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> >> The way that compilers work is that the warnings are generated in the front end while the optimization level affects the backend. That means that -O3 has no effect on the code that does error generation. This remark about -O3 being needed to make -Werror useful is just plain wrong. |
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> > |
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> > Huh? -O3 enables more checks, which can generate more warnings. |
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> |
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> What checks are those? -O3 affects backend optimization while warnings are generated by the front end. Once the immediate representation is generated, there are no other warnings aside from those from the linker. |
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https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html |
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Search for "depend on" |
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-> [...] estimated based on heuristics that depend on thelevel |
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argument and on optimization |
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-> Because these warnings depend on optimization [...] |
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Yes, warnings are dependent on optimization level. |
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