Merge pull request #130 from wezm/parse-const #174

Job	Run time
Rustfmt	15s
Test (stable)	20s
Test (1.64.0)	52s
Test (1.60.0)	1m 4s
Test (1.58.1)	1m 6s
Test (beta)	19s
Test (nightly)	20s
Test example (actix, stable)	1m 30s
Test example (actix, nightly)	1m 25s
Test example (axum, stable)	57s
Test example (axum, nightly)	56s
Test example (gotham, stable)	1m 9s
Test example (gotham, nightly)	1m 18s
Test example (iron, stable)	39s
Test example (iron, nightly)	49s
Test example (nickel, stable)	46s
Test example (nickel, nightly)	53s
Test example (simple, stable)	24s
Test example (simple, nightly)	20s
Test example (static-sass, stable)	32s
Test example (static-sass, nightly)	36s
Test example (statics, stable)	20s
Test example (statics, nightly)	20s
Test example (tide, stable)	1m 10s
Test example (tide, nightly)	1m 10s
Test example (warp03, stable)	1m 28s
Test example (warp03, nightly)	1m 8s
	22m 6s

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