This topic shouldn’t even require a blog post, but I find the CMake CLI usage rather odd when it comes to specifying a generator. Here’s a shortened "-h" output.

> cmake -h
Usage

cmake [options] <path-to-source>
cmake [options] <path-to-existing-build>
cmake [options] -S <path-to-source> -B <path-to-build>

Specify a source directory to (re-)generate a build system for it in the
current working directory.  Specify an existing build directory to
re-generate its build system.

Options
-S <path-to-source>          = Explicitly specify a source directory.
-B <path-to-build>           = Explicitly specify a build directory.
-C <initial-cache>           = Pre-load a script to populate the cache.
-D <var>[:<type>]=<value>    = Create or update a cmake cache entry.
-U <globbing_expr>           = Remove matching entries from CMake cache.
-G <generator-name>          = Specify a build system generator.
-T <toolset-name>            = Specify toolset name if supported by
                                generator.
-A <platform-name>           = Specify platform name if supported by
                                generator.

    ...snip...

Generators

The following generators are available on this platform (* marks default):
Visual Studio 16 2019        = Generates Visual Studio 2019 project files.
                                Use -A option to specify architecture.
Visual Studio 15 2017 [arch] = Generates Visual Studio 2017 project files.
                                Optional [arch] can be "Win64" or "ARM".

    ...snip...

Borland Makefiles            = Generates Borland makefiles.
* NMake Makefiles              = Generates NMake makefiles.
NMake Makefiles JOM          = Generates JOM makefiles.
MSYS Makefiles               = Generates MSYS makefiles.
MinGW Makefiles              = Generates a make file for use with
                                mingw32-make.
Unix Makefiles               = Generates standard UNIX makefiles.

    ...snip...
    
Kate - Ninja                 = Generates Kate project files.
Kate - Unix Makefiles        = Generates Kate project files.
Eclipse CDT4 - NMake Makefiles
                            = Generates Eclipse CDT 4.0 project files.
Eclipse CDT4 - MinGW Makefiles
                            = Generates Eclipse CDT 4.0 project files.
Eclipse CDT4 - Ninja         = Generates Eclipse CDT 4.0 project files.
Eclipse CDT4 - Unix Makefiles= Generates Eclipse CDT 4.0 project files.

These generator options do not look like valid parameter values to the "-G" option. But they are. So, if you want to compile on Windows using MinGW, you have to use this.

> cmake -S ../src -B ./ -G "MinGW Makefiles"

Or, if you prefer Visual Studio project files:

> cmake -S ../ -B ./ -G "Visual Studio 15 2017 Win64"

This "syntax" looks weird, and it tripped me for about 10 minutes until I found a sample and understood how it works.