Add SQL style linter (Postgres-Extensions/linter)

.github/workflows/ci.yml

@@ -5,6 +5,18 @@ on:
       - master
   pull_request:
 jobs:
+  lint:
+    name: 🧹 SQL lint
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v4
+      - name: make lint
+        # Deliberately not pre-initializing the .vendor/linter submodule via
+        # `submodules:` above -- letting `make lint` self-init it (lint.mk)
+        # is what actually proves that works from a plain clone.
+        run: make lint
+
   test:
     strategy:
       matrix:

.gitmodules

@@ -0,0 +1,3 @@
+[submodule ".vendor/linter"]
+	path = .vendor/linter
+	url = https://github.com/Postgres-Extensions/linter.git

Makefile

@@ -2,3 +2,8 @@ include pgxntool/base.mk
 
 # Temporary hack
 testdeps: $(wildcard test/*/*.sql) $(wildcard test/*.sql) # Be careful not to include directories in this
+
+# sql/count_nulls.sql is the hand-written source the versioned sql/count_nulls--*.sql
+# files are generated/derived from; those aren't relinted (see linter's DESIGN.md).
+LINT_TARGETS = sql/count_nulls.sql test/
+include lint.mk

lint.mk

@@ -0,0 +1,7 @@
+# lint.mk — thin wrapper; the whole local footprint for consuming
+# https://github.com/Postgres-Extensions/linter. Everything else lives in
+# the .vendor/linter submodule; see its README for available targets/rules.
+.vendor/linter/lint.mk:
+	git submodule update --init -- .vendor/linter
+
+include .vendor/linter/lint.mk

test/core/functions.sql

@@ -12,7 +12,7 @@ $$;
  * mistake!
  */
 
-/*
+/* EXCLUDED CODE — unused boilerplate template for new test functions, not meant to be enabled
 CREATE FUNCTION test__
 () RETURNS SETOF text LANGUAGE plpgsql AS $body$
 DECLARE
@@ -180,7 +180,7 @@ BEGIN
   );
 
   -- Doesn't work for array types
-  /*
+  /* EXCLUDED CODE — doesn't work for array types
   RETURN NEXT bag_eq(
     $$SELECT a, b, c, null_count( array[a], array[b], array[c] ) FROM test_data$$
     , $$SELECT * FROM test_data$$