diff options
Diffstat (limited to 'gcc/doc/invoke.texi')
| -rw-r--r-- | gcc/doc/invoke.texi | 75 |
1 files changed, 69 insertions, 6 deletions
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index f60865b..0980230 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -433,7 +433,8 @@ Objective-C and Objective-C++ Dialects}. -Wunsuffixed-float-constants -Wunterminated-string-initialization -Wunused --Wunused-but-set-parameter -Wunused-but-set-variable +-Wunused-but-set-parameter -Wunused-but-set-parameter=@var{n} +-Wunused-but-set-variable -Wunused-but-set-variable=@var{n} -Wunused-const-variable -Wunused-const-variable=@var{n} -Wunused-function -Wunused-label -Wunused-local-typedefs -Wunused-macros @@ -7921,27 +7922,89 @@ statement. @opindex Wunused-but-set-parameter @opindex Wno-unused-but-set-parameter @item -Wunused-but-set-parameter +@option{-Wunused-but-set-parameter} is the same as +@option{-Wunused-but-set-parameter=3} and +@option{-Wno-unused-but-set-parameter} is the same as +@option{-Wunused-but-set-parameter=0}. + +@opindex Wunused-but-set-parameter= +@item -Wunused-but-set-parameter=@var{n} Warn whenever a function parameter is assigned to, but otherwise unused (aside from its declaration). To suppress this warning use the @code{unused} attribute (@pxref{Variable Attributes}). -This warning is also enabled by @option{-Wunused} together with -@option{-Wextra}. +@option{-Wunused-but-set-parameter=0} disables the warning. +With @option{-Wunused-but-set-parameter=1} all uses except initialization +and left hand side of assignment which is not further used disable the +warning. +With @option{-Wunused-but-set-parameter=2} additionally uses of parameter +in @code{++} and @code{--} operators don't count as uses. +And finally with @option{-Wunused-but-set-parameter=3} additionally +uses in @var{parm} @code{@var{@@}=} @var{rhs} outside of @var{rhs} don't +count as uses. See @option{-Wunused-but-set-variable=@var{n}} option for +examples. + +This @option{-Wunused-but-set-parameter=3} warning is also enabled by +@option{-Wunused} together with @option{-Wextra}. @opindex Wunused-but-set-variable @opindex Wno-unused-but-set-variable @item -Wunused-but-set-variable +@option{-Wunused-but-set-variable} is the same as +@option{-Wunused-but-set-variable=3} and +@option{-Wno-unused-but-set-variable} is the same as +@option{-Wunused-but-set-variable=0}. + +@opindex Wunused-but-set-variable= +@item -Wunused-but-set-variable=@var{n} Warn whenever a local variable is assigned to, but otherwise unused (aside from its declaration). -This warning is enabled by @option{-Wall}. +This @option{-Wunused-but-set-variable=3} warning is enabled by @option{-Wall}. To suppress this warning use the @code{unused} attribute (@pxref{Variable Attributes}). -This warning is also enabled by @option{-Wunused}, which is enabled -by @option{-Wall}. +@option{-Wunused-but-set-variable=0} disables the warning. +With @option{-Wunused-but-set-variable=1} all uses except initialization +and left hand side of assignment which is not further used disable the +warning. +With @option{-Wunused-but-set-variable=2} additionally uses of variable +in @code{++} and @code{--} operators don't count as uses. +And finally with @option{-Wunused-but-set-variable=3} additionally +uses in @var{parm} @code{@var{@@}=} @var{rhs} outside of @var{rhs} don't +count as uses. + +This @option{-Wunused-but-set-variable=3} warning is also enabled by +@option{-Wunused}, which is enabled by @option{-Wall}. + +@smallexample +void foo (void) +@{ + int a = 1; // @option{-Wunused-variable} warning + int b = 0; // Warning for @var{n} >= 1 + b = 1; b = 2; + int c = 0; // Warning for @var{n} >= 2 + ++c; c--; --c; c++; + int d = 0; // Warning for @var{n} >= 3 + d += 4; + int e = 0; // No warning, cast to void + (void) e; + int f = 0; // No warning, f used + int g = f = 5; + (void) g; + int h = 0; // No warning, preincrement used + int i = ++h; + (void) i; + int j = 0; // No warning, postdecrement used + int k = j--; + (void) k; + int l = 0; // No warning, l used + int m = l |= 2; + (void) m; +@} +@end smallexample @opindex Wunused-function @opindex Wno-unused-function |