Datasheet

C and C++ Compilers

By default, unused declaration warnings are given for:

• local (within a function) declarations of variables, typedefs, and

functions

• labels (always within a function)

• top-level static functions and static variables.

-Wy

This option turns off warnings about deprecated features.

2.3.11 Specifying additional checks

The options described below give you control over the extent and rigor of the checks.

Additional checking is an aid to portability and is good coding practice.

-fa

This option checks for certain types of data flow anomalies. The compiler

performs data flow analysis as part of code generation. The checks

indicate when an automatic variable might have been used before being

assigned a value. The check is pessimistic and sometimes reports an

anomaly where there is none. In general, it is useful at some stage to

check all code using

-fa

-fh

This option checks that:

• all external objects are declared before use

• all file-scoped static objects are used

• all predeclarations of static functions are used between their

declaration and their definition. For example:

static int f(void);

static int f(void){return 1;}

line 2: Warning: unused earlier static declaration of 'f'

• external objects declared only in included header files are used in a

source file.

These checks directly support good modular programming practices.

When writing production software, use the

-fh

option only in the later

stages of program development. The extra diagnostics can be annoying in

the earlier stages.

-fp

This option reports on explicit casts of integers to pointers, for example:

char *cp = (char *) anInteger;

This warning indicates potential portability problems. Casting explicitly

between pointers and integers, although not clean, is not harmful on the

ARM processor where both are 32-bit types. This option also causes casts

to the same type to produce a warning. For example: