Add intrinsic property function to compare versions

[nguerrera]

Usage:

$([MSBuild]::VersionEquals(a, b))
$([MSBuild]::VersionNotEquals(a, b))
$([MSBuild]::VersionLessThan(a, b))
$([MSBuild]::VersionLessThanOrEquals(a, b))
$([MSBuild]::VersionLessThan(a, b))
$([MSBuild]::VersionGreaterThanOrEquals(a, b))

Versions are parsed like System.Version, with the following exceptions:

• Leading v or V is ignored. Allows comparison to $(TargetFrameworkVersion)

• Everything from first '-' or '+' to end of string is ignored. Allows passing in semantic versions, though the order is not the same as semver. Instead, prerelease specified and build metadata do not have any sorting weight. This can be useful, for example, to turn on a feature for >= x.y and have it kick in on x.y.z-pre.

• Unspecified parts are same as zero value parts. (x == x.0 == x.0.0 == x.0.0.0)

• Whitespace is not allowed in integer components

• major version only is valid ("3" is equal to "3.0.0.0")

• + is not allowed as positive sign in integer components (it is treated as semver metadata and ignored per above)

The parser is adapted from System.Version source code, but simplified and tweaked to handle quirks above, with trivial opportunities to improve perf / reduce allocations taken. Tests are also adapted from corefx.

Fix #3212

[rainersigwald]

Big question: Is this sufficiently ergonomic? Or should we have $([MSBuild]::VersionGreater(a, b)) and friends to fit more easily into conditions?

If you can build a project that uses this with the env var MSBuildLogPropertyFunctionsRequiringReflection=1 and don't see it logged, then I guess we don't need a fast-path for it, but we do have fastpaths for string methods so I suspect we might. Should be easy to throw in Expander.cs

[nguerrera]

I like the idea of having better ergonomics for conditions.

So, how about all of these:

VersionGreaterThan
VersionGreaterThanOrEquals
VersionLessThan
VersionLessThanOrEquals
VersionEquals
VersionNotEquals

And relegate comparison that returns an int to an implementation detail.

I added Than because VersionLess read like version-less (as in having no version) to me.

EDIT: Tweaked this comment to reflect where I landed while doing it.

[nguerrera]

Perhaps VersionNotEquals is unnecessary since leading !$([MSBuild]::VersionEquals(a, b)) is pretty readable and fewer characters anyway?

[rainersigwald]

LGTM. I could go either way on VersionNotEquals vs !VersionEquals but you already wrote it so let's leave it?

[eerhardt]

Did we consider having a IsVersion or TryParse kind of method along with these? That way someone could use it for $(LangVersion), which may be of the form x.y, but it also may be latest, preview, etc.