https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101649
--- Comment #4 from South Window <make_...@t-online.de> --- For the user of GCC it doesn't matter whether GCC at compile times converts the literal to a double, and then notices that 32 bits of are zero, and uses a float instead, or if GCC knows right away that 0.5 (and others) don't need to be promoted. Promoting first and then completely undoing the promotion is a purely internal process, effectively a null operation that is of no interest of the user of the compiler. One of the most relevant scopes for -Wdouble-promotion is probably optimization (in particular for SIMD), where the unintended use of a double would cause a significant performance hit. But if the compiler is smart enough and is not using doubles and double instructions, and no precision is changed anywhere in the process, it should be smart enough to not through a this warning.
