The error messages say 'Unknown modifier' or 'Bad modifier', which is
not entirely correct. The modifier in itself is valid, it's just that
make doesn't expect the end of the string after the modifier.
The table was created by manually inspecting the code of the various
ApplyModifier functions in var.c.
The modifiers are listed in alphabetical order, except for the SysV
modifier, which is listed at the end since it is used as a fallback
modifier for many other modifiers and because it does not have a fixed
prefix.
Since 2008-12-21, make has silently ignored strange variable names in
constructs like '$$', '$}', '$' followed by nothing. Ignoring these
bugs in makefiles instead of reporting them is not a good idea.
To improve the situation, make complains about these errors now, but
only in lint mode (-dL). This preserves existing behavior while still
allowing to validate existing makefiles that they don't depend on this
bug.
If the test phase goes well, these error messages may be enabled
unconditionally.
https://mail-index.netbsd.org/pkgsrc-users/2020/09/12/msg032229.html
The test names have been derived from the current manual page.
All these tests are dummies right now, and the code from the existing
tests will be moved into the new tests step by step.
This is done to prevent modmisc, escape, varmod-edge and varmisc from
growing without any bounds, and to reduce the side-effects of one test
to the others.
rillig