From a05e09ba486a4fa54d2fdfb48bea4d7b290f00d7 Mon Sep 17 00:00:00 2001 From: Chandler Carruth Date: Thu, 16 Jun 2011 02:00:04 +0000 Subject: [PATCH] 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. llvm-svn: 133136 --- clang/lib/Sema/SemaChecking.cpp | 4 +++- clang/test/SemaCXX/warn-memset-bad-sizeof.cpp | 7 ++++--- 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp index d45ebf9033d6..945964fc351c 100644 --- a/clang/lib/Sema/SemaChecking.cpp +++ b/clang/lib/Sema/SemaChecking.cpp @@ -1866,7 +1866,9 @@ void Sema::CheckMemsetcpymoveArguments(const CallExpr *Call, if (const PointerType *DestPtrTy = DestTy->getAs()) { 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). diff --git a/clang/test/SemaCXX/warn-memset-bad-sizeof.cpp b/clang/test/SemaCXX/warn-memset-bad-sizeof.cpp index 9221590bd9ea..167f05f3daff 100644 --- a/clang/test/SemaCXX/warn-memset-bad-sizeof.cpp +++ b/clang/test/SemaCXX/warn-memset-bad-sizeof.cpp @@ -23,10 +23,11 @@ inline Dest bit_cast(const Source& source) { } // 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 @@ void f(char fake_array[8], Mat m, const Foo& const_foo) { // 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 @@ void f(char fake_array[8], Mat m, const Foo& const_foo) { 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));