This has two significant effects:
1) Direct relational comparisons between null pointer constants (0 and nullopt)
and pointers are now ill-formed. This was always the case for C, and it
appears that C++ only ever permitted by accident. For instance, cases like
nullptr < &a
are now rejected.
2) Comparisons and conditional operators between differently-cv-qualified
pointer types now work, and produce a composite type that both source
pointer types can convert to (when possible). For instance, comparison
between 'int **' and 'const int **' is now valid, and uses an intermediate
type of 'const int *const *'.
Clang previously supported #2 as an extension.
We do not accept the cases in #1 as an extension. I've tested a fair amount of
code to check that this doesn't break it, but if it turns out that someone is
relying on this, we can easily add it back as an extension.
This is a re-commit of r284800.
llvm-svn: 284890
This has two significant effects:
1) Direct relational comparisons between null pointer constants (0 and nullopt)
and pointers are now ill-formed. This was always the case for C, and it
appears that C++ only ever permitted by accident. For instance, cases like
nullptr < &a
are now rejected.
2) Comparisons and conditional operators between differently-cv-qualified
pointer types now work, and produce a composite type that both source
pointer types can convert to (when possible). For instance, comparison
between 'int **' and 'const int **' is now valid, and uses an intermediate
type of 'const int *const *'.
Clang previously supported #2 as an extension.
We do not accept the cases in #1 as an extension. I've tested a fair amount of
code to check that this doesn't break it, but if it turns out that someone is
relying on this, we can easily add it back as an extension.
llvm-svn: 284800
Thisadds a new warning that warns on code like this:
if (memcmp(a, b, sizeof(a) != 0))
The warning looks like:
test4.cc:5:30: warning: size argument in 'memcmp' call is a comparison [-Wmemsize-comparison]
if (memcmp(a, b, sizeof(a) != 0))
~~~~~~~~~~^~~~
test4.cc:5:7: note: did you mean to compare the result of 'memcmp' instead?
if (memcmp(a, b, sizeof(a) != 0))
^ ~
)
test4.cc:5:20: note: explicitly cast the argument to size_t to silence this warning
if (memcmp(a, b, sizeof(a) != 0))
^
(size_t)( )
1 warning generated.
This found 2 bugs in chromium and has 0 false positives on both chromium and
llvm.
The idea of triggering this warning on a binop in the size argument is due to
rnk.
llvm-svn: 198063
Richard Smith