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Document -Wuninitialized for allocated objects.

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gcc/ChangeLog:

	* doc/invoke.texi (-Wuninitialized): Document -Wuninitialized for
	allocated objects.
	 (-Wmaybe-uninitialized): Same.
This commit is contained in:
Martin Sebor 2020-09-17 09:07:09 -06:00
parent 21fdebc519
commit 90e4dcb79a
1 changed files with 21 additions and 8 deletions
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gcc/doc/invoke.texi
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@ -6513,9 +6513,15 @@ either specify @option{-Wextra -Wunused} (note that @option{-Wall} implies
@item -Wuninitialized
@opindex Wuninitialized
@opindex Wno-uninitialized
Warn if an automatic variable is used without first being initialized.
In C++, warn if a non-static reference or non-static @code{const}
member appears in a class without constructors.
Warn if an object with automatic or allocated storage duration is used
without having been initialized. In C++, also warn if a non-static
reference or non-static @code{const} member appears in a class without
constructors.
In addition, passing a pointer (or in C++, a reference) to an uninitialized
object to a @code{const}-qualified argument of a built-in function known to
read the object is also diagnosed by this warning.
(@option{-Wmaybe-uninitialized} is issued for ordinary functions.)
If you want to warn about code that uses the uninitialized value of the
variable in its own initializer, use the @option{-Winit-self} option.
@ -6557,11 +6563,18 @@ void store (int *i)
@item -Wmaybe-uninitialized
@opindex Wmaybe-uninitialized
@opindex Wno-maybe-uninitialized
For an automatic (i.e.@: local) variable, if there exists a path from the
function entry to a use of the variable that is initialized, but there exist
some other paths for which the variable is not initialized, the compiler
emits a warning if it cannot prove the uninitialized paths are not
executed at run time.
For an object with automatic or allocated storage duration, if there exists
a path from the function entry to a use of the object that is initialized,
but there exist some other paths for which the object is not initialized,
the compiler emits a warning if it cannot prove the uninitialized paths
are not executed at run time.
In addition, passing a pointer (or in C++, a reference) to an uninitialized
object to a @code{const}-qualified function argument is also diagnosed by
this warning. (@option{-Wuninitialized} is issued for built-in functions
known to read the object.) Annotating the function with attribute
@code{access (none)} indicates that the argument isn't used to access
the object and avoids the warning (@pxref{Common Function Attributes}).
These warnings are only possible in optimizing compilation, because otherwise
GCC does not keep track of the state of variables.