Use 'constexpr' when including pio header files from a C++ compiler #2651
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In particular this allows compile-time checks to be performed on the contents of pio_program structs via 'static_assert'. This could be used (for example) to confirm that multiple PIO programs fit in a single PIO module and abort compilation if not. Fixes raspberrypi#2650
lurch
reviewed
Sep 8, 2025
| @@ -79,6 +79,13 @@ struct c_sdk_output : public output_format { | |||
| fprintf(out, "#endif\n"); | |||
| fprintf(out, "\n"); | |||
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| fprintf(out, "#ifdef __cplusplus\n"); | |||
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https://en.cppreference.com/w/cpp/language/constexpr.html says that constexpr was only added in C++11, so should this line perhaps be
Suggested change
| fprintf(out, "#ifdef __cplusplus\n"); | |
| fprintf(out, "#if defined(__cplusplus) && defined(__cpp_constexpr)\n"); |
so that it doesn't break older C++ compilers? (Or perhaps simply #ifdef __cpp_constexpr is sufficient?)
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In particular this allows compile-time checks to be performed on the contents of pio_program structs via 'static_assert'.
This could be used (for example) to confirm that multiple PIO programs fit in a single PIO module and abort compilation if not.
Fixes #2650