[cfe-commits] r133136 - in /cfe/trunk: lib/Sema/SemaChecking.cpp test/SemaCXX/warn-memset-bad-sizeof.cpp
Nico Weber
thakis at chromium.org
Wed Jun 15 19:27:00 PDT 2011
On Wed, Jun 15, 2011 at 7:00 PM, Chandler Carruth <chandlerc at gmail.com> wrote:
> Author: chandlerc
> Date: Wed Jun 15 21:00:04 2011
> New Revision: 133136
>
> URL: http://llvm.org/viewvc/llvm-project?rev=133136&view=rev
> Log:
> Skip both character pointers and void pointers when diagnosing bad
> argument types for mem{set,cpy,move}. Character pointers, much like void
> pointers, often point to generic "memory", so trying to check whether
> they match the type of the argument to 'sizeof' (or other checks) is
> unproductive and often results in false positives.
>
> Nico, please review; does this miss any of the bugs you were trying to
> find with this warning? The array test case you had should be caught by
> the array-specific sizeof warning I think.
Yes, now it doesn't find http://codereview.chromium.org/7167009/
Can you provide any examples where this warns when it shouldn't? (…and
maybe revert this in the meantime?)
>
> Modified:
> cfe/trunk/lib/Sema/SemaChecking.cpp
> cfe/trunk/test/SemaCXX/warn-memset-bad-sizeof.cpp
>
> Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=133136&r1=133135&r2=133136&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaChecking.cpp Wed Jun 15 21:00:04 2011
> @@ -1866,7 +1866,9 @@
> if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
> QualType PointeeTy = DestPtrTy->getPointeeType();
>
> - if (PointeeTy->isVoidType())
> + // Don't warn about void pointers or char pointers as both are often used
> + // for directly representing memory, regardless of its underlying type.
> + if (PointeeTy->isVoidType() || PointeeTy->isCharType())
> continue;
>
> // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p).
>
> Modified: cfe/trunk/test/SemaCXX/warn-memset-bad-sizeof.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/warn-memset-bad-sizeof.cpp?rev=133136&r1=133135&r2=133136&view=diff
> ==============================================================================
> --- cfe/trunk/test/SemaCXX/warn-memset-bad-sizeof.cpp (original)
> +++ cfe/trunk/test/SemaCXX/warn-memset-bad-sizeof.cpp Wed Jun 15 21:00:04 2011
> @@ -23,10 +23,11 @@
> }
>
> // http://www.lysator.liu.se/c/c-faq/c-2.html#2-6
> -void f(char fake_array[8], Mat m, const Foo& const_foo) {
> +void f(Mat m, const Foo& const_foo) {
> S s;
> S* ps = &s;
> PS ps2 = &s;
> + char c = 42;
> char arr[5];
> char* parr[5];
> Foo foo;
> @@ -42,8 +43,6 @@
> // expected-warning {{the argument to sizeof is pointer type 'typeof (ps2)' (aka 'S *'), expected 'S' to match first argument to 'memset'}}
> memset(ps2, 0, sizeof(PS)); // \
> // expected-warning {{the argument to sizeof is pointer type 'PS' (aka 'S *'), expected 'S' to match first argument to 'memset'}}
> - memset(fake_array, 0, sizeof(fake_array)); // \
> - // expected-warning {{the argument to sizeof is pointer type 'char *', expected 'char' to match first argument to 'memset'}}
>
> memcpy(&s, 0, sizeof(&s)); // \
> // expected-warning {{the argument to sizeof is pointer type 'S *', expected 'S' to match first argument to 'memcpy'}}
> @@ -69,6 +68,8 @@
> memcpy(&foo, &const_foo, sizeof(Foo));
> memcpy((void*)&s, 0, sizeof(&s));
> memcpy(0, (void*)&s, sizeof(&s));
> + memcpy(&parr[3], &c, sizeof(&c));
> + memcpy((char*)&parr[3], &c, sizeof(&c));
>
> CFooRef cfoo = foo;
> memcpy(&foo, &cfoo, sizeof(Foo));
>
>
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