19 Diagnostics library [diagnostics]

19.7 Debugging [debugging]

19.7.1 General [debugging.general]

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Subclause [debugging] describes functionality to introspect and interact with the execution of the program.
[Note 1: 
The facilities provided by the debugging functionality interact with a program that could be tracing the execution of a C++ program, such as a debugger.
— end note]

19.7.2 Header <debugging> synopsis [debugging.syn]

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// all freestanding namespace std { // [debugging.utility], utility void breakpoint() noexcept; void breakpoint_if_debugging() noexcept; bool is_debugger_present() noexcept; }

19.7.3 Utility [debugging.utility]

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void breakpoint() noexcept;
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The semantics of this function are implementation-defined.
[Note 1: 
When invoked, the execution of the program temporarily halts and execution is handed to the debugger until such a time as: The program is terminated by the debugger, or the debugger resumes execution of the program as if the function was not invoked.
— end note]
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void breakpoint_if_debugging() noexcept;
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Effects: Equivalent to: if (is_debugger_present()) breakpoint();
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bool is_debugger_present() noexcept;
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Replaceable: A C++ program may define a function with this function signature, and thereby displace the default version defined by the C++ standard library.
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Required behavior: This function has no preconditions.
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Default behavior: implementation-defined.
[Note 2: 
When tracing the execution of a program with a debugger, an implementation returns true.
An implementation performs an immediate query, as needed, to determine if the program is traced by a debugger.
On Windows or equivalent systems, this can be achieved by calling the ​::​IsDebuggerPresent() Win32 function.
On POSIX, this can be achieved by checking for a tracer parent process, with best effort determination that such a tracer parent process is a debugger.
— end note]