tradcpp(1) on OpenBSD
The text adaac815fe5b, as OpenBSD 6.3, OpenBSD 6.2, OpenBSD 6.1 shipped it.
traditional (K&R-style) C macro preprocessor
Flags it lists
-
-C -
-CC -
-Dmacro -
-H -
-Ipath -
-M -
-MD -
-MF -
-MG -
-MM -
-MMD -
-MP -
-MQ -
-MT -
-P -
-Umacro -
-Wall -
-Wcomment -
-Werror -
-Wno-endif-labels -
-Wundef -
-Wunused-macros -
-dD -
-dI -
-dM -
-dN -
-fdollars-in-identifiers -
-fno-dollars-in-identifiers -
-ftabstop -
-idirafter -
-imacros -
-include -
-iprefix -
-iquote -
-iremap -
-isysroot -
-isystem -
-iwithprefix -
-iwithprefixbefore -
-nostdinc -
-std -
-traditional -
-undef -
-w -
-x