[Sema] Add sizeof diagnostics for bzero

For memset (and others) we can get diagnostics like:

  struct stat { int x; };
  void foo(struct stat *stamps) {
    bzero(stamps, sizeof(stamps));
    memset(stamps, 0, sizeof(stamps));
  }

  t.c:7:28: warning: 'memset' call operates on objects of type 'struct stat' while the size is based on a different type 'struct stat *' [-Wsizeof-pointer-memaccess]
    memset(stamps, 0, sizeof(stamps));
           ~~~~~~            ^~~~~~
  t.c:7:28: note: did you mean to dereference the argument to 'sizeof' (and multiply it by the number of elements)?
    memset(stamps, 0, sizeof(stamps));
                             ^~~~~~

This patch implements the same class of warnings for bzero.

Differential Revision: https://reviews.llvm.org/D22525

rdar://problem/18963514

llvm-svn: 277787

1 files changed, 5 insertions, 3 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index a6069cf..a534ead 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -6179,13 +6179,15 @@ void Sema::CheckMemaccessArguments(const CallExpr *Call,
 
   // It is possible to have a non-standard definition of memset.  Validate
   // we have enough arguments, and if not, abort further checking.
-  unsigned ExpectedNumArgs = (BId == Builtin::BIstrndup ? 2 : 3);
+  unsigned ExpectedNumArgs =
+      (BId == Builtin::BIstrndup || Builtin::BIbzero ? 2 : 3);
   if (Call->getNumArgs() < ExpectedNumArgs)
     return;
 
-  unsigned LastArg = (BId == Builtin::BImemset ||
+  unsigned LastArg = (BId == Builtin::BImemset || BId == Builtin::BIbzero ||
                       BId == Builtin::BIstrndup ? 1 : 2);
-  unsigned LenArg = (BId == Builtin::BIstrndup ? 1 : 2);
+  unsigned LenArg =
+      (BId == Builtin::BIbzero || BId == Builtin::BIstrndup ? 1 : 2);
   const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts();
 
   if (CheckMemorySizeofForComparison(*this, LenExpr, FnName,