Add -Wstring-plus-int, which warns on "str" + int and int + "str".

It doesn't warn if the integer is known at compile time and within
the bounds of the string.

Discussion: http://comments.gmane.org/gmane.comp.compilers.clang.scm/47203



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@151943 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 62 insertions, 0 deletions

diff --git a/test/SemaCXX/string-plus-int.cpp b/test/SemaCXX/string-plus-int.cpp
new file mode 100644
index 0000000000..3be3f07033
--- /dev/null
+++ b/test/SemaCXX/string-plus-int.cpp
@@ -0,0 +1,62 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -Wno-array-bounds %s -fpascal-strings
+
+void consume(const char* c) {}
+void consume(const unsigned char* c) {}
+void consume(const wchar_t* c) {}
+void consumeChar(char c) {}
+
+enum MyEnum {
+  kMySmallEnum = 1,
+  kMyEnum = 5
+};
+
+enum OperatorOverloadEnum {
+  kMyOperatorOverloadedEnum = 5
+};
+
+const char* operator+(const char* c, OperatorOverloadEnum e) {
+  return "yo";
+}
+
+const char* operator+(OperatorOverloadEnum e, const char* c) {
+  return "yo";
+}
+
+void f(int index) {
+  // Should warn.
+  consume("foo" + 5);  // expected-warning {{adding 'int' to a string does not append to the string}} expected-note {{use array indexing to silence this warning}}
+  consume("foo" + index);  // expected-warning {{adding 'int' to a string does not append to the string}} expected-note {{use array indexing to silence this warning}}
+  consume("foo" + kMyEnum);  // expected-warning {{adding 'MyEnum' to a string does not append to the string}} expected-note {{use array indexing to silence this warning}}
+
+  consume(5 + "foo");  // expected-warning {{adding 'int' to a string does not append to the string}} expected-note {{use array indexing to silence this warning}}
+  consume(index + "foo");  // expected-warning {{adding 'int' to a string does not append to the string}} expected-note {{use array indexing to silence this warning}}
+  consume(kMyEnum + "foo");  // expected-warning {{adding 'MyEnum' to a string does not append to the string}} expected-note {{use array indexing to silence this warning}}
+
+  // FIXME: suggest replacing with "foo"[5]
+  consumeChar(*("foo" + 5));  // expected-warning {{adding 'int' to a string does not append to the string}} expected-note {{use array indexing to silence this warning}}
+  consumeChar(*(5 + "foo"));  // expected-warning {{adding 'int' to a string does not append to the string}} expected-note {{use array indexing to silence this warning}}
+
+  consume(L"foo" + 5);  // expected-warning {{adding 'int' to a string does not append to the string}} expected-note {{use array indexing to silence this warning}}
+
+  // Should not warn.
+  consume(&("foo"[3]));
+  consume(&("foo"[index]));
+  consume(&("foo"[kMyEnum]));
+  consume("foo" + kMySmallEnum);
+  consume(kMySmallEnum + "foo");
+
+  consume(L"foo" + 2);
+
+  consume("foo" + 3);  // Points at the \0
+  consume("foo" + 4);  // Points 1 past the \0, which is legal too.
+  consume("\pfoo" + 4);  // Pascal strings don't have a trailing \0, but they
+                         // have a leading length byte, so this is fine too.
+
+  consume("foo" + kMyOperatorOverloadedEnum);
+  consume(kMyOperatorOverloadedEnum + "foo");
+
+  #define A "foo"
+  #define B "bar"
+  consume(A B + sizeof(A) - 1);
+}
+