Add check-weeds script

This script also gets run as part of `scripts/check.sh`.

Since `check-weeds` has to do much of the same work as
`check-formatting`, I extracted the common code to a separate Bash file.

Also made it so the scripts don’t have to be run from the repo root
directory.

Author: sellout

scripts/check-formatting

@@ -1,29 +1,14 @@
 #!/usr/bin/env bash
 set -euo pipefail
+SCRIPTDIR="$(dirname -- "$(readlink -f -- "${BASH_SOURCE[0]}")")"
 
-mode=${1:-check}
-
-## This would ideally be read from ./nix/versions.nix, but we can’t assume the user has Nix, so we hardcode this, then
-## at the end of the script, if the user _does_ have Nix, we check if this hardcoded version is the one we want.
-ormolu_version="0.7.2.0"
+source "$SCRIPTDIR/check-version.bash"
 
-if command -v ormolu >/dev/null; then
-    if ormolu --version | grep -q "${ormolu_version}"; then
-        find . -name '*.hs' -not -path "*/dist-newstyle/*" -not -path "*/.stack-work/*" -print0 \
-            | xargs -0 ormolu --check-idempotence --mode "${mode}"
-    else
-        >&2 echo "Found Ormolu, but the version isn’t ${ormolu_version}:"
-        >&2 ormolu --version
-        >&2 echo "skipping format check"
-    fi
-else
-    >&2 echo "Ormolu not found on PATH, skipping format check"
-fi
+mode=${1:-check}
 
-## When the user has Nix, ensure that `ormolu_version` matches what we require for Nix.
-if command -v nix >/dev/null; then
-    expected_version="$(nix eval --file ./nix/versions.nix ormolu --raw)"
-    if [[ "$expected_version" != "$ormolu_version" ]]; then
-        >&2 echo "⚠️ Please update ‘ormolu_version’ in $0 to ${expected_version} and open a PR."
-    fi
+if version-equals ormolu "0.7.2.0"; then
+    ## We `cd` so Ormolu can find its .ormolu configuration.
+    cd "$SCRIPTDIR/.."
+    find . -name '*.hs' -not -path "*/dist-newstyle/*" -not -path "*/.stack-work/*" -print0 \
+        | xargs -0 ormolu --check-idempotence --mode "${mode}"
 fi

scripts/check-version.bash

@@ -0,0 +1,47 @@
+SCRIPTNAME="$(readlink -f -- "${BASH_SOURCE[0]}")"
+SCRIPTDIR="$(dirname -- "$SCRIPTNAME")"
+
+# shellcheck disable=SC2120
+# because the argument is optional
+function indent() {
+    local indentSize=2
+    local indent=${1:-1}
+    pr -to $((indent * indentSize))
+}
+
+## This function checks
+## 1. that the command is on PATH,
+## 2. that the version of the command found matches our expectation (command must support `--version`), and
+## 3. if the user has Nix, that our expectation matches the version specified by our Nix config.
+##
+## Failing either of the first two checks causes an error, while the third is only a warning (because the third
+## indicates a code issue, not a user issue).
+function version-equals {
+    local command="$1"
+    ## This would ideally be read from ./nix/versions.nix, but we can’t assume the user has Nix, so we hardcode this,
+    ## then at the end of the script, if the user _does_ have Nix, we check if this hardcoded version is the one we
+    ## want.
+    local expected_version="$2"
+
+    if command -v "$command" >/dev/null; then
+        if ! "$command" --version | grep -q "${expected_version}"; then
+            >&2 echo "Skipping $command check – found, but the version isn’t ${expected_version}:"
+            "$command" --version | indent >&2
+            exit 78
+        fi
+    else
+        >&2 echo "Skipping $command check – not found on PATH"
+        exit 127
+    fi
+
+    ## When the user has Nix, check that `expected_version` matches what we require for Nix.
+    if command -v nix >/dev/null; then
+        nix_reported_version="$(nix eval --file $SCRIPTDIR/../nix/versions.nix "$command" --raw)"
+        if [[ "$expected_version" != "$nix_reported_version" ]]; then
+            >&2 echo "⚠️ Running $command check with unexpected version."
+            >&2 echo "  Please update ‘version-equals ${command} \"$expected_version\"’ called from"
+            >&2 echo "  $SCRIPTNAME"
+            >&2 echo "  to use \"$nix_reported_version\" and open a PR."
+        fi
+    fi
+}

scripts/check-weeds

@@ -0,0 +1,31 @@
+#!/usr/bin/env bash
+set -euo pipefail
+SCRIPTDIR="$(dirname -- "$(readlink -f -- "${BASH_SOURCE[0]}")")"
+
+source "$SCRIPTDIR/check-version.bash"
+
+if version-equals weeder "2.8.0"; then
+    ## We `cd` so Weeder can find all the files.
+    cd "$SCRIPTDIR/.."
+    ## Weeder gets confused by HIE files in the Direnv cache, but doesn’t let us exclude a directory from HIE search
+    ## (ocharles/weeder#201). So this enumerates the directories we _do_ want to search.
+    ##
+    ## TODO: Populate the `--hie-directory` list with something like
+    ##       `find . -type d -name ".stack-work" -exec dirname "{}" \;` to keep it from going stale.
+    weeder \
+        --require-hs-files --no-default-fields \
+        --hie-directory ./codebase2 \
+        --hie-directory ./lib \
+        --hie-directory ./parser-typechecker \
+        --hie-directory ./unison-cli \
+        --hie-directory ./unison-cli-integration \
+        --hie-directory ./unison-cli-main \
+        --hie-directory ./unison-core \
+        --hie-directory ./unison-hashing-v2 \
+        --hie-directory ./unison-merge \
+        --hie-directory ./unison-runtime \
+        --hie-directory ./unison-share-api \
+        --hie-directory ./unison-share-projects-api \
+        --hie-directory ./unison-syntax \
+        --hie-directory ./yaks
+fi

scripts/check.sh

@@ -1,4 +1,10 @@
-#!/bin/bash
+#!/usr/bin/env bash
+set -euo pipefail
+SCRIPTDIR="$(dirname -- "$(readlink -f -- "${BASH_SOURCE[0]}")")"
+
+## TODO: `transcripts` should be able to take a search path, but since it currently looks for files relative to its run
+##       path, we `cd` to where it can find them.
+cd "$SCRIPTDIR/.."
 
 true \
   && stack build --fast --test \
@@ -7,4 +13,5 @@ true \
   && stack exec unison transcript unison-src/transcripts-manual/rewrites.md \
   && stack exec unison transcript unison-src/transcripts-manual/docs.to-html.md \
   && stack exec cli-integration-tests \
+  && ./scripts/check-weeds \
   && ./scripts/check-formatting