On Mon, Feb 11, 2019 at 11:41 PM Krzysztof Kozlowski <krzk@xxxxxxxxxx> wrote: > > On Mon, 11 Feb 2019 at 19:40, Gustavo A. R. Silva > <gustavo@xxxxxxxxxxxxxx> wrote: > > > > In preparation to enabling -Wimplicit-fallthrough, mark switch > > cases where we are expecting to fall through. > > > > This patch fixes the following warnings: > > > > drivers/clk/samsung/clk-s3c2443.c: In function ‘s3c2443_common_clk_init’: > > drivers/clk/samsung/clk-s3c2443.c:390:3: warning: this statement may fall through [-Wimplicit-fallthrough=] > > samsung_clk_register_alias(ctx, s3c2450_aliases, > > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > ARRAY_SIZE(s3c2450_aliases)); > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > drivers/clk/samsung/clk-s3c2443.c:393:2: note: here > > case S3C2416: > > ^~~~ > > > > Warning level 3 was used: -Wimplicit-fallthrough=3 > > > > Notice that, in this particular case, the code comment is modified > > in accordance with what GCC is expecting to find. > > > > This patch is part of the ongoing efforts to enable > > -Wimplicit-fallthrough. > > I saw this in multiple places already and I think fix is wrong. The > point is that the code is correct - the fall through is marked > properly. > > It is just the GCC which has to be fixed not the code. You want to > adjust the code for specific version of GCC and what if GCC changes > its warning? For example GCC might require "fall through: "... or any > other syntax. Another point - what about clang's syntax? -Wimplicit-fallthrough=3 is stricter and maps to -Wextra, hence its choice. GCC's levels were chosen based on the existing linters, static analyzers, etc. The patterns are unlikely to change (see the gcc man-page). Clang doesn't recognize anything in C mode (hopefully this will be fixed in the future[1]). As long as one of the compilers is able to check this, we'll avoid the bugs associated with this mis-pattern. Gustavo's efforts here have found kind of a lot of bugs, so I think it's worth a little churn to add these (and make minor adjustments to existing comments). [1] https://bugs.llvm.org/show_bug.cgi?id=37135 -- Kees Cook
