Add -Wstring-plus-char, which warns when adding char literals to C strings.

Specifically, this warns when a character literal is added (using '+') to a
variable with type 'char *' (or any other pointer to character type). Like
-Wstring-plus-int, there is a fix-it to change "foo + 'a'" to "&foo['a']"
iff the character literal is on the right side of the string.

Patch by Anders Rönnholm!

llvm-svn: 193418

1 files changed, 15 insertions, 0 deletions

diff --git a/clang/test/Sema/string-plus-char.c b/clang/test/Sema/string-plus-char.c
new file mode 100644
index 00000000000..322e8f5962b
--- /dev/null
+++ b/clang/test/Sema/string-plus-char.c
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+void f(const char *s) {
+  char *str = 0;
+  char *str2 = str + 'c'; // expected-warning {{adding 'char' to a string pointer does not append to the string}} expected-note {{use array indexing to silence this warning}}
+
+  const char *constStr = s + 'c'; // expected-warning {{adding 'char' to a string pointer does not append to the string}} expected-note {{use array indexing to silence this warning}}
+
+  str = 'c' + str;// expected-warning {{adding 'char' to a string pointer does not append to the string}} expected-note {{use array indexing to silence this warning}}
+
+  // no-warning
+  char c = 'c';
+  str = str + c;
+  str = c + str;
+}