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06814834a6
Add `AllowedTypes` options to support custom defined char like type. treat `unsigned char` and `signed char` as char like type by default. The allowed types only effect when the var decl or explicit cast to this non-canonical type names. Fixed: #133425
59 lines
2.0 KiB
ReStructuredText
59 lines
2.0 KiB
ReStructuredText
.. title:: clang-tidy - bugprone-unintended-char-ostream-output
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bugprone-unintended-char-ostream-output
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=======================================
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Finds unintended character output from ``unsigned char`` and ``signed char`` to an
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``ostream``.
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Normally, when ``unsigned char (uint8_t)`` or ``signed char (int8_t)`` is used, it
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is more likely a number than a character. However, when it is passed directly to
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``std::ostream``'s ``operator<<``, the result is the character output instead
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of the numeric value. This often contradicts the developer's intent to print
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integer values.
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.. code-block:: c++
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uint8_t v = 65;
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std::cout << v; // output 'A' instead of '65'
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The check will suggest casting the value to an appropriate type to indicate the
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intent, by default, it will cast to ``unsigned int`` for ``unsigned char`` and
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``int`` for ``signed char``.
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.. code-block:: c++
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std::cout << static_cast<unsigned int>(v); // when v is unsigned char
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std::cout << static_cast<int>(v); // when v is signed char
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To avoid lengthy cast statements, add prefix ``+`` to the variable can also
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suppress warnings because unary expression will promote the value to an ``int``.
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.. code-block:: c++
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std::cout << +v;
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Or cast to char to explicitly indicate that output should be a character.
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.. code-block:: c++
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std::cout << static_cast<char>(v);
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Options
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-------
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.. option:: AllowedTypes
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A semicolon-separated list of type names that will be treated like the ``char``
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type: the check will not report variables declared with with these types or
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explicit cast expressions to these types. Note that this distinguishes type
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aliases from the original type, so specifying e.g. ``unsigned char`` here
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will not suppress reports about ``uint8_t`` even if it is defined as a
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``typedef`` alias for ``unsigned char``.
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Default is `unsigned char;signed char`.
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.. option:: CastTypeName
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When `CastTypeName` is specified, the fix-it will use `CastTypeName` as the
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cast target type. Otherwise, fix-it will automatically infer the type.
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