• Proposal
• Dart Sass (Add support for constants in calculations dart-sass#1922)
• Tests (Add tests for calculation constants sass-spec#1890)
• Documentation (Document constants in calculations sass-site#707)
• Update canonical spec ([Calc Constants] Merge into the canonical spec #3519)

Values and Units 4 defines pi, e, infinity, -infinity, and NaN constants for use in calc() expressions. We should support these as they land in browsers. The current status (as of 8 February 2022) is:

• infinity: landing in Chrome 99
• -infinity: landing in Chrome 99
• NaN: landing in Chrome 99
• pi: unsupported anywhere as far as I can tell
• e: unsupported anywhere as far as I can tell

For the degenerate constants (infinity, -infinity, and NaN) we should not only support parsing them in calc() expressions but also serializing Sass numbers with those values to calc() expressions.