[Bug target/88535] sparcv9 gcc 7 causes comparison failure in sparc gcc 8 dwarf2out.o

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88535

--- Comment #11 from john henning <mailboxnotfound at yahoo dot com> ---
> There are 3 different switches: --build, --host and --target.

Hmm.  I must be looking in the wrong place for documentation; are these
explained somewhere?  

At https://gcc.gnu.org/install/configure.html I see a description of 
   --target
and a brief mention of 
   --host
but no definition.  There doesn't seem to be a description for --build.