Building on Windows with MinGW-w64 needs a separate configuration

[SilviaHyde]

The problem

On WIndows with MinGW-w64 compiler, the build.wls script doesn't work out of the box.

When running the script from CMD, I got the following error message:

CreateLibrary::instl: The compiler installation directive "CompilerInstallation" -> $Failed does not indicate a usable installation of MinGW (executable: g++.exe).

Expected behavior

Expecting the package be built successfully.

Version

gcc (x86_64-posix-seh-rev0, Built by MinGW-W64 project) 8.1.0

Windows 10 (Version 1909)

Additional context

It seems, in scripts/buildInit.wl, some options in CreateLibrary needs special treatment:

SetReplace/scripts/buildInit.wl

Lines 36 to 44 in ea09f2c

	"CompileOptions" -> Switch[$OperatingSystem,
	"Windows",
	{"/std:c++17", "/EHsc"},
	"MacOSX",
	Join[{"-std=c++17"}, $warningsFlags, {"-mmacosx-version-min=10.12"}], (* for std::shared_mutex support *)
	"Unix",
	Join[{"-std=c++17"}, $warningsFlags]],
	"Compiler" -> ToExpression @ tryEnvironment["COMPILER", Automatic],
	"CompilerInstallation" -> tryEnvironment["COMPILER_INSTALLATION", Automatic],

I can make the compilation successful with manually specifying the compiler:

Needs["CCompilerDriver`MinGWCompiler`"];
$CCompiler = {"Name" -> "MinGW", "Compiler" -> MinGWCompiler, "CompilerInstallation" -> "C:\\mingw-w64\\x86_64-8.1.0-posix-seh\\mingw64\\bin", "CompilerName" -> "g++.exe"};

and replacing the above referenced options with just a

  "CompileOptions" -> Join[{"-std=c++17"}, $warningsFlags]