edid-decode @20230804: error: use of undeclared identifier 'nullptr'

[ryandesign (Ryan Carsten Schmidt)]

​https://build.macports.org/builders/ports-10.7_x86_64-builder/builds/154784/steps/install-port/logs/stdio

edid-decode.cpp:303:22: error: no member named 'to_string' in namespace 'std'
        unsigned len = std::to_string(cta.preparsed_total_dtds).length();
                       ~~~~~^
edid-decode.cpp:601:19: error: no member named 'to_string' in namespace 'std'
                add_str(s, std::to_string(t->hsize_mm) + " mm x " + std::to_string(t->vsize_mm) + " mm");
                           ~~~~~^
edid-decode.cpp:601:60: error: no member named 'to_string' in namespace 'std'
                add_str(s, std::to_string(t->hsize_mm) + " mm x " + std::to_string(t->vsize_mm) + " mm");
                                                                    ~~~~~^
edid-decode.cpp:1652:3: error: use of undeclared identifier 'nullptr'
                nullptr
                ^
edid-decode.cpp:1662:17: error: use of undeclared identifier 'nullptr'
        if (opt_str == nullptr && opt != CVT_INTERLACED && opt != CVT_ALT &&
                       ^
edid-decode.cpp:1671:28: error: use of undeclared identifier 'nullptr'
                *value = strtod(opt_str, nullptr);
                                         ^

The mention of nullptr makes clear that this software requires C++11, and the compiler hasn't been told to use C++11 mode.

The solution will probably be something like:

compiler.cxx_standard 2011
configure.cxxflags-append -std=c++11

[wwalexander (William Alexander)]

I've updated the Portfile with the suggested lines. What's the best way if any to test the behavior on older systems? Thank you for the guidance!

[ryandesign (Ryan Carsten Schmidt)]

You can test on older systems using an older Mac or a virtual machine running on a newer Mac. But even though I have both of these I usually don't bother. If a change seems likely to fix a problem, I often just commit it and later check to see if that fixed the build on the buildbot. I like monitoring the ​buildbot waterfall but build status eventually makes its way into the ​ports web site too.

[ryandesign (Ryan Carsten Schmidt)]

See my comment above.

Also, sometimes you don't need an older system to verify a fix. For example, here we know nullptr is a C++11 feature, so we need to ensure a C++11 compiler is used and that it is told to be in C++11 mode.

compiler.cxx_standard 2011 ensures the former, presuming that the build system correctly uses CXX to invoke the C++ compiler. You can test whether this is the case on any OS version by doing a build and specifying a nonstandard compiler, for example sudo port build edid-decode configure.compiler=macports-clang-16, then greping through the log to make sure that every compilation happened via that compiler (/opt/local/bin/clang++-mp-16).

configure.cxxflags-append -std=c++11 ensures the latter, presuming that the build system correctly passes CXXFLAGS to every C++ compiler invocation. You can test whether this is the case on any OS version by doing a build and then greping through the log for any occurrences of bin/clang++ that do not also include -std=c++11. Looking at ​the project's Makefile, it looks like it does not use CXXFLAGS; it erroneously passes CFLAGS to the C++ compiler. Upstream should fix this.

Upstream should also be adding -std=c++11 to CXXFLAGS in the Makefile without us having to do it.

[William Alexander <wwalexander@…>]

In f3e38e7d0197030e11bf55f81175fe22a0a2ab26/macports-ports (master):

edid-decode: fix Portfile whitespace

• add blank line after modeline as specified by port lint --nitpick
• move destroot args to separate lines

References: #67934

[William Alexander <wwalexander@…>]

In 497f2b14cc269a4dc7479b0be99a3a3d43644493/macports-ports (master):

edid-decode: specify C++ 2011 standard

• patch Makefile to use CXXFLAGS instead of CFLAGS
• specify C++ 2011 to support building on older machines

References: #67934

[wwalexander (William Alexander)]

This should be fixed by ​https://github.com/macports/macports-ports/pull/20270. Could you verify?