bsla_warning.h

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/// @file bsla_warning.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bsla_warning.h                                                     -*-C++-*-
#ifndef INCLUDED_BSLA_WARNING
#define INCLUDED_BSLA_WARNING
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bsla_warning bsla_warning
/// @brief  Provide a macro to emit a warning when a function is called.
/// @addtogroup bsl
/// @{
/// @addtogroup bsla
/// @{
/// @addtogroup bsla_warning
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bsla_warning-purpose"> Purpose</a>
/// * <a href="#bsla_warning-macros"> Macros </a>
/// * <a href="#bsla_warning-description"> Description </a>
///   * <a href="#bsla_warning-macro-reference"> Macro Reference </a>
///   * <a href="#bsla_warning-usage"> Usage </a>
///     * <a href="#bsla_warning-example-1-function-annotated-with-bsla_warning"> Example 1: Function Annotated with BSLA_WARNING </a>
///
/// # Purpose {#bsla_warning-purpose}
/// Provide a macro to emit a warning when a function is called.
///
/// # Macros {#bsla_warning-macros}
///
/// -  BSLA_WARNING(QUOTED_MESSAGE): emit warning message during compilation
/// -  BSLA_WARNING_IS_ACTIVE:       defined if `BSLA_WARNING` is active
///
/// @see  bsla_annotations
///
/// # Description {#bsla_warning-description}
/// This component provides a macro that indicates that a compiler
/// warning should be emitted when a given function is called.
///
/// ## Macro Reference {#bsla_warning-macro-reference}
///
///
///  `BSLA_WARNING(QUOTED_MESSAGE)`:
///      This annotation, when used, will cause a compile-time warning
///      containing the specified `QUOTED_MESSAGE`, which must be a string
///      contained in double quotes, when a call to the so-annotated function is
///      not removed through dead-code elimination or other optimizations.
///      While it is possible to leave the function undefined, thus incurring a
///      link-time failure, with the use of this macro the invalid call will be
///      diagnosed earlier (i.e., at compile time), and the diagnostic will
///      include the location of the function call.
/// 
///  `BSLA_WARNING_IS_ACTIVE`:
///      The macro `BSLA_WARNING_IS_ACTIVE` is defined if `BSLA_WARNING` expands
///      to something with the desired effect; otherwise
///      `BSLA_WARNING_IS_ACTIVE` is not defined and `BSLA_WARNING` expands to
///      nothing.
///
/// ## Usage {#bsla_warning-usage}
///
///
/// This section illustrates intended use of this component.
///
/// ### Example 1: Function Annotated with BSLA_WARNING {#bsla_warning-example-1-function-annotated-with-bsla_warning}
///
///
/// First, we declare and define a function annotated with `BSLA_WARNING`.  Note
/// that the argument to `BSLA_WARNING` must be a quoted string:
/// @code
/// /// Do nothing.
/// void usageFunc() BSLA_WARNING("Don't call 'usageFunc'");
///
/// void usageFunc()
/// {
/// }
/// @endcode
/// Now, in `main`, we call `usageFunc`:
/// @code
///     usageFunc();
/// @endcode
/// Finally, observe the following warning issued by the compiler:
/// @code
/// .../bsla_warning.t.cpp: In function 'int main(int, char**)':
/// .../bsla_warning.t.cpp:246:16: warning: call to 'usageFunc' declared with
/// attribute warning: Don't call 'usageFunc'
///      usageFunc();
///                 ^
/// @endcode
/// @}
/** @} */
/** @} */
 
/** @addtogroup bsl
 * @{
 */
/** @addtogroup bsla
 * @{
 */
/** @addtogroup bsla_warning
 * @{
 */
 
#include <bsls_platform.h>
 
                       // =============================
                       // Checks for Pre-Defined macros
                       // =============================
 
#if defined(BSLA_WARNING)
#error BSLA_WARNING is already defined!
#endif
 
#if defined(BSLA_WARNING_IS_ACTIVE)
#error BSLA_WARNING_IS_ACTIVE is already defined!
#endif
 
                       // =========================
                       // Set macros as appropriate
                       // =========================
 
#if defined(BSLS_PLATFORM_CMP_GNU)
    // The '__warning__' attribute is not supported by clang as of version
    // 8.0.0.
 
    #define BSLA_WARNING(x) __attribute__((__warning__(x)))
 
    #define BSLA_WARNING_IS_ACTIVE 1
#else
    #define BSLA_WARNING(x)
#endif
 
#endif
 
// ----------------------------------------------------------------------------
// Copyright 2019 Bloomberg Finance L.P.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ----------------------------- END-OF-FILE ----------------------------------
 
/** @} */
/** @} */
/** @} */