On Wed, Mar 28, 2012 at 20:30, David Mathog wrote: > ... > >> gcc -std=c99 -pedantic -Wall -O0 -fdump-tree-gimple d.c > > > That's a trick worth knowing. Thanks! > Ran that on a test program and in every case but one there was an implicit > > (int) b > > on sections of code which I though should generate warnings. (Math ops on > bools, comparison operations of > bool with ints.) The one exception in that little program was: > > b=2; > > which came out as > > b=1; > > In that case the compiler must have performed an implicit > > 1 = (bool) 2 > > Also these forms all generated implicit int conversions > > if(b==1) > if(b==2) > if(b==0) > > whereas > > if(b) > > did not. > > So let's turn this around. If the compiler warned on all implicit > conversions of bool <-> int, > what program lines would it warn on that it shouldn't? It would warn on: > > if(b==1) > if(b==0) > > but I would argue that line is inappropriate for a bool type, and should be > written as: > > if(b) > > With two bool variables, this also did not generate an implicit conversion > (and so would not warn, > which is appropriate): > > if(b1 || b2) > > Whereas this less preferred form would have generated an implicit (int) [and > a well deserved warning] > > if(b1 + b2)
Your suggestion is probably a good idea, but as with all good ideas, it will probably not get implemented because most people don't care. Therefore, I'd suggest writing a patch and submitting it; people will no doubt be a lot more receptive when you convey your thoughts in hard-nosed, precise code, ESPECIALLY because that means the work has already been done! Sincerely, Michael Witten
