Add a setgitversion script to update the version string with git

.github/workflows/build.yml

@@ -16,9 +16,12 @@ jobs:
 
       - name: Checkout repository
         uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
 
       - name: Package Source
         run: |
+          ./setgitversion
           mkdir source
           cabal sdist
           mv dist-newstyle/sdist/*.tar.gz source/source.tar.gz

setgitversion

@@ -0,0 +1,11 @@
+#!/bin/sh -xe
+# This script hardcodes the `git describe` version as ShellCheck's version number.
+# This is done to allow shellcheck --version to differ from the cabal version when
+# building git snapshots.
+
+file="src/ShellCheck/Data.hs"
+test -e "$file"
+tmp=$(mktemp)
+version=$(git describe)
+sed -e "s/=.*VERSIONSTRING.*/= \"$version\" -- VERSIONSTRING, DO NOT SUBMIT/" "$file" > "$tmp"
+mv "$tmp" "$file"

src/ShellCheck/Data.hs

@@ -4,7 +4,7 @@ import ShellCheck.Interface
 import Data.Version (showVersion)
 import Paths_ShellCheck (version)
 
-shellcheckVersion = showVersion version
+shellcheckVersion = showVersion version -- VERSIONSTRING
 
 internalVariables = [
     -- Generic