Generates common zero-initialized values for tentative definitions.
Tentative definitions are declarations of variables with no storage class and no initializer.
-fcommon option places the tentative
definitions in a common block. This common definition is not associated with any
particular section or object, so multiple definitions resolve to a single symbol
definition at link time.
-fno-common option generates individual zero-initialized definitions for tentative definitions. These zero-initialized definitions are placed in a ZI section in the generated object. Multiple definitions of the same symbol in different files can cause a
L6200E: Symbol multiply defined linker error, because the individual definitions conflict with each other.
The default is