[clang-tidy] Check for suspicious string assignments.

It is possible to assign arbitrary integer types to strings.
Sometimes it is the result of missing to_string call or apostrophes.

Reviewers: alexfh

Differential Revision: http://reviews.llvm.org/D15411

llvm-svn: 255630

2 files changed, 32 insertions, 0 deletions

diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index 2f1686fa995..f8001440e73 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -48,6 +48,7 @@ List of clang-tidy Checks
    misc-non-copyable-objects
    misc-sizeof-container
    misc-static-assert
+   misc-string-integer-assignment
    misc-swapped-arguments
    misc-throw-by-value-catch-by-reference
    misc-undelegated-constructor
diff --git a/clang-tools-extra/docs/clang-tidy/checks/misc-string-integer-assignment.rst b/clang-tools-extra/docs/clang-tidy/checks/misc-string-integer-assignment.rst
new file mode 100644
index 00000000000..4e2aeef2183
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/misc-string-integer-assignment.rst
@@ -0,0 +1,31 @@
+misc-string-integer-assignment
+==============================
+
+The check finds assignments of an integer to ``std::basic_string<CharT>``
+(``std::string``, ``std::wstring``, etc.). The source of the problem is the
+following assignment operator of ``std::basic_string<CharT>``:
+
+.. code:: c++
+  basic_string& operator=( CharT ch );
+
+Numeric types can be implicity casted to character types.
+
+.. code:: c++
+  std::string s;
+  int x = 5965;
+  s = 6;
+  s = x;
+
+Use the appropriate conversion functions or character literals.
+
+.. code:: c++
+  std::string s;
+  int x = 5965;
+  s = '6';
+  s = std::to_string(x);
+
+In order to suppress false positives, use an explicit cast.
+
+.. code:: c++
+  std::string s;
+  s = static_cast<char>(6);