Red Hat ENTERPRISE LINUX 4 Manual page 49

Chapter 4. GCC Command Options
the system headers of most modern systems, e.g. the
Use of these macros in user code might normally lead to spurious warnings, however GCC's
integrated preprocessor has enough context to avoid warning in these cases.
A function declared external in one block and then used after the end of the block.
•
A statement has an operand of type
• switch
A non-
•
static
some traditional C compilers.
The ISO type of an integer constant has a different width or signedness from its traditional
•
type. This warning is only issued if the base of the constant is ten. I.e. hexadecimal or octal
values, which typically represent bit patterns, are not warned about.
Usage of ISO string concatenation is detected.
•
Initialization of automatic aggregates.
•
Identifier conflicts with labels. Traditional C lacks a separate namespace for labels.
•
Initialization of unions. If the initializer is zero, the warning is omitted. This is done under
•
the assumption that the zero initializer in user code appears conditioned on e.g.
avoid missing initializer warnings and relies on default initialization to zero in the traditional
C case.
Conversions by prototypes between fixed/floating point values and vice versa. The absence of
•
these prototypes when compiling with traditional C would cause serious problems. This is a
subset of the possible conversion warnings, for the full set use
Use of ISO C style function definitions. This warning intentionally is not issued for prototype
•
declarations or variadic functions because these ISO C features will appear in your code when
using libiberty's traditional C compatibility macros,
also bypassed for nested functions because that feature is already a GCC extension and thus
not relevant to traditional C compatibility.
-Wdeclaration-after-statement (C only)
Warn when a declaration is found after a statement in a block. This construct, known from C++,
was introduced with ISO C99 and is by default allowed in GCC. It is not supported by ISO C90
and was not supported by GCC versions before GCC 3.0. Section 6.24 Mixed Declarations and
Code.
-Wundef
Warn if an undefined identifier is evaluated in an
-Wendif-labels
Warn whenever an
-Wshadow
Warn whenever a local variable shadows another local variable, parameter or global variable or
whenever a built-in function is shadowed.
-Wlarger-than-
len
Warn whenever an object of larger than
function declaration follows a
or an
#else #endif
_MIN
.
long
one. This construct is not accepted by
static
PARAMS
directive.
#if
are followed by text.
bytes is defined.
len
/ macros in
_MAX limits.h
__STDC__
.
-Wconversion
and . This warning is
VPARAMS
41
.
to