[clang-tidy] Add a checker for zero-length memset.

If there's memset(x, y, 0) in the code it's most likely a mistake. The
checker suggests a fix-it to swap 'y' and '0'.

I think this has the potential to be promoted into a general clang warning
after some testing in clang-tidy.

Differential Revision: http://reviews.llvm.org/D4535

llvm-svn: 213155

1 files changed, 51 insertions, 0 deletions

diff --git a/clang-tools-extra/test/clang-tidy/google-memset-zero-length.cpp b/clang-tools-extra/test/clang-tidy/google-memset-zero-length.cpp
new file mode 100644
index 00000000000..262eb51d625
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/google-memset-zero-length.cpp
@@ -0,0 +1,51 @@
+// RUN: $(dirname %s)/check_clang_tidy_fix.sh %s google-runtime-memset %t
+// REQUIRES: shell
+
+void *memset(void *, int, __SIZE_TYPE__);
+
+namespace std {
+  using ::memset;
+}
+
+template <int i>
+void memtmpl() {
+  memset(0, sizeof(int), i);
+  memset(0, sizeof(int), 0);
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: memset of size zero, potentially swapped argument
+// CHECK-FIXES: memset(0, 0, sizeof(int));
+}
+
+void foo(void *a, int xsize, int ysize) {
+  memset(a, sizeof(int), 0);
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: memset of size zero, potentially swapped argument
+// CHECK-FIXES: memset(a, 0, sizeof(int));
+#define M memset(a, sizeof(int), 0);
+  M
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: memset of size zero, potentially swapped argument
+// CHECK-FIXES: #define M memset(a, sizeof(int), 0);
+  ::memset(a, xsize *
+           ysize, 0);
+// CHECK-MESSAGES: :[[@LINE-2]]:3: warning: memset of size zero, potentially swapped argument
+// CHECK-FIXES: ::memset(a, 0, xsize *
+// CHECK-FIXES-NEXT: ysize);
+  std::memset(a, sizeof(int), 0x00);
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: memset of size zero, potentially swapped argument
+// CHECK-FIXES: std::memset(a, 0x00, sizeof(int));
+
+  const int v = 0;
+  memset(a, sizeof(int), v);
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: memset of size zero, potentially swapped argument
+// CHECK-FIXES: memset(a, v, sizeof(int));
+
+  memset(a, sizeof(int), v + v);
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: memset of size zero, potentially swapped argument
+// CHECK-FIXES: memset(a, v + v, sizeof(int));
+
+  memset(a, sizeof(int), v + 1);
+
+  memset(a, -1, sizeof(int));
+  memset(a, 0xcd, 1);
+  memset(a, v, 0);
+
+  memtmpl<0>();
+}