Warn on mismatched parentheses in memcmp and friends.
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
diff --git a/clang/test/SemaCXX/warn-memsize-comparison.cpp b/clang/test/SemaCXX/warn-memsize-comparison.cpp
new file mode 100644
index 0000000..54c410e
--- /dev/null
+++ b/clang/test/SemaCXX/warn-memsize-comparison.cpp
@@ -0,0 +1,93 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+//
+
+typedef __SIZE_TYPE__ size_t;
+extern "C" void *memset(void *, int, size_t);
+extern "C" void *memmove(void *s1, const void *s2, size_t n);
+extern "C" void *memcpy(void *s1, const void *s2, size_t n);
+extern "C" void *memcmp(void *s1, const void *s2, size_t n);
+extern "C" int strncmp(const char *s1, const char *s2, size_t n);
+extern "C" int strncasecmp(const char *s1, const char *s2, size_t n);
+extern "C" char *strncpy(char *dst, const char *src, size_t n);
+extern "C" char *strncat(char *dst, const char *src, size_t n);
+extern "C" char *strndup(const char *src, size_t n);
+extern "C" size_t strlcpy(char *dst, const char *src, size_t size);
+extern "C" size_t strlcat(char *dst, const char *src, size_t size);
+
+void f() {
+ char b1[80], b2[80];
+ if (memset(b1, 0, sizeof(b1) != 0)) {} // \
+ expected-warning{{size argument in 'memset' call is a comparison}} \
+ expected-note {{did you mean to compare}} \
+ expected-note {{explicitly cast the argument}}
+ if (memset(b1, 0, sizeof(b1)) != 0) {}
+
+ if (memmove(b1, b2, sizeof(b1) == 0)) {} // \
+ expected-warning{{size argument in 'memmove' call is a comparison}} \
+ expected-note {{did you mean to compare}} \
+ expected-note {{explicitly cast the argument}}
+ if (memmove(b1, b2, sizeof(b1)) == 0) {}
+
+ if (memcpy(b1, b2, sizeof(b1) < 0)) {} // \
+ expected-warning{{size argument in 'memcpy' call is a comparison}} \
+ expected-note {{did you mean to compare}} \
+ expected-note {{explicitly cast the argument}}
+ if (memcpy(b1, b2, sizeof(b1)) < 0) {}
+
+ if (memcmp(b1, b2, sizeof(b1) <= 0)) {} // \
+ expected-warning{{size argument in 'memcmp' call is a comparison}} \
+ expected-note {{did you mean to compare}} \
+ expected-note {{explicitly cast the argument}}
+ if (memcmp(b1, b2, sizeof(b1)) <= 0) {}
+
+ if (strncmp(b1, b2, sizeof(b1) > 0)) {} // \
+ expected-warning{{size argument in 'strncmp' call is a comparison}} \
+ expected-note {{did you mean to compare}} \
+ expected-note {{explicitly cast the argument}}
+ if (strncmp(b1, b2, sizeof(b1)) > 0) {}
+
+ if (strncasecmp(b1, b2, sizeof(b1) >= 0)) {} // \
+ expected-warning{{size argument in 'strncasecmp' call is a comparison}} \
+ expected-note {{did you mean to compare}} \
+ expected-note {{explicitly cast the argument}}
+ if (strncasecmp(b1, b2, sizeof(b1)) >= 0) {}
+
+ if (strncpy(b1, b2, sizeof(b1) == 0 || true)) {} // \
+ expected-warning{{size argument in 'strncpy' call is a comparison}} \
+ expected-note {{did you mean to compare}} \
+ expected-note {{explicitly cast the argument}}
+ if (strncpy(b1, b2, sizeof(b1)) == 0 || true) {}
+
+ if (strncat(b1, b2, sizeof(b1) - 1 >= 0 && true)) {} // \
+ expected-warning{{size argument in 'strncat' call is a comparison}} \
+ expected-note {{did you mean to compare}} \
+ expected-note {{explicitly cast the argument}}
+ if (strncat(b1, b2, sizeof(b1) - 1) >= 0 && true) {}
+
+ if (strndup(b1, sizeof(b1) != 0)) {} // \
+ expected-warning{{size argument in 'strndup' call is a comparison}} \
+ expected-note {{did you mean to compare}} \
+ expected-note {{explicitly cast the argument}}
+ if (strndup(b1, sizeof(b1)) != 0) {}
+
+ if (strlcpy(b1, b2, sizeof(b1) != 0)) {} // \
+ expected-warning{{size argument in 'strlcpy' call is a comparison}} \
+ expected-note {{did you mean to compare}} \
+ expected-note {{explicitly cast the argument}}
+ if (strlcpy(b1, b2, sizeof(b1)) != 0) {}
+
+ if (strlcat(b1, b2, sizeof(b1) != 0)) {} // \
+ expected-warning{{size argument in 'strlcat' call is a comparison}} \
+ expected-note {{did you mean to compare}} \
+ expected-note {{explicitly cast the argument}}
+ if (strlcat(b1, b2, sizeof(b1)) != 0) {}
+
+ if (memset(b1, 0, sizeof(b1) / 2)) {}
+ if (memset(b1, 0, sizeof(b1) >> 2)) {}
+ if (memset(b1, 0, 4 << 2)) {}
+ if (memset(b1, 0, 4 + 2)) {}
+ if (memset(b1, 0, 4 - 2)) {}
+ if (memset(b1, 0, 4 * 2)) {}
+
+ if (memset(b1, 0, (size_t)(sizeof(b1) != 0))) {}
+}