针对 K&R C 与 Sun ISO C 之间的差异发出警告。
-xtransition 选项与 -Xa 和 -Xt 选项一起使用时将发出警告。通过适当编码,可以消除关于不同行为的所有警告消息。除非使用 -xtransition 选项,否则不再出现以下警告:
\a is ISO C “alert” character
\x is ISO C hex escape
bad octal digit
base type is really type tag: name
comment is replaced by “##”
comment does not concatenate tokens
declaration introduces new type in ISO C: type tag
macro replacement within a character constant
macro replacement within a string literal
no macro replacement within a character constant
no macro replacement within a string literal
operand treated as unsigned
trigraph sequence replaced
ISO C treats constant as unsigned: operator
semantics of operator change in ISO C; use explicit cast