build: Improve sqlite implementation selection method.

The build option is now compatible with go build.

To build with mattn sqlite, pass the flag "-tag sqlite_mattn". To build with modernc sqlite, pass the flag "-tag sqlite_modernc".

When building via Bazel, that flag is injected via .blazerc with the line:

"common --show_timestamps --define gotags=sqlite_modernc"

Gazelle also needs to be supplied with that tag. For gazelle gotags must be passed as:

"-build_tags tag1,tag2,..."

This is accomplished by adding a pair of config_setting() calls that translate the gotags define into a setting tag and by using a select keyed on that to pass the appropriate flag to Gazelle. Gazelle update-repos does not need to know about the go tag.

On the Makefile side, Gazelle is now called with "-args" to pass those arguments that aare variables in the Makefile, allowing the others to be chosen and appended by Blaze rules.

It was noticed that make licenses implies a full build and therefore should be done last. (At least not before gazelle.)

.bazelrc

@@ -1,5 +1,6 @@
 ### common options for all subcommands (help, query, build, ...)
-common --show_timestamps
+common --show_timestamps --define gotags=sqlite_modernc
+
 # connect to buchgr/bazel-remote cache
 # These flags can unfortunately not be specified for `common`, as they are not accepted by all subcommands (help, version, dump)
 build --remote_cache=grpc://localhost:9092 --experimental_remote_downloader=grpc://localhost:9092

BUILD.bazel

@@ -17,7 +17,40 @@ load("@cgrindel_bazel_starlib//updatesrc:defs.bzl", "updatesrc_update_all")
 # gazelle:exclude doc/**
 # gazelle:exclude rules_openapi/tools/node_modules/**
 # gazelle:exclude tools/lint/**/testdata/src/**
-gazelle(name = "gazelle")
+
+# This is simplistic but the complete, by-the-everchanging-bazel-book, solution
+# is ludicrously complicated. Go there if and when needed.
+config_setting(
+    name = "sqlite_mattn",
+    define_values = {
+        "gotags": "sqlite_mattn",
+    },
+)
+
+config_setting(
+    name = "sqlite_modernc",
+    define_values = {
+        "gotags": "sqlite_modernc",
+    },
+)
+
+gazelle(
+    name = "gazelle",
+    build_tags = select({
+        ":sqlite_modernc": ["sqlite_modernc"],
+        ":sqlite_mattn": ["sqlite_mattn"],
+    }),
+    command = "update",
+    extra_args = [
+        "-go_naming_convention",
+        "go_default_library",
+    ],
+)
+
+gazelle(
+    name = "gazelle_update_repos",
+    command = "update-repos",
+)
 
 go_lint_config(
     name = "go_lint_config",

Makefile

@@ -10,7 +10,7 @@ build: bazel
 # Use NOTPARALLEL to force correct order.
 # Note: From GNU make 4.4, this still allows building any other targets (e.g. lint) in parallel.
 .NOTPARALLEL: all
-all: go_deps.bzl protobuf mocks gazelle licenses build antlr write_all_source_files
+all: go_deps.bzl protobuf mocks gazelle build antlr write_all_source_files licenses
 
 clean:
 	bazel clean
@@ -32,7 +32,8 @@ go.mod:
 	bazel run --config=quiet @go_sdk//:bin/go -- mod tidy
 
 go_deps.bzl: go.mod
-	bazel run --config=quiet //:gazelle -- update-repos -prune -from_file=go.mod -to_macro=go_deps.bzl%go_deps
+	@# gazelle is run with "-args"; so our arguments are added to those from the gazelle() rule. 
+	bazel run --verbose_failures --config=quiet //:gazelle_update_repos -- -args -prune -from_file=go.mod -to_macro=go_deps.bzl%go_deps
 	@# XXX(matzf): clean up; gazelle update-repose inconsistently inserts blank lines (see bazelbuild/bazel-gazelle#1088).
 	@sed -e '/def go_deps/,$${/^$$/d}' -i go_deps.bzl
 
@@ -58,10 +59,10 @@ mocks:
 	tools/gomocks.py
 
 gazelle: go_deps.bzl
-	tools/licenses.sh
-	bazel run //:gazelle --config=quiet -- update -mode=$(GAZELLE_MODE) -go_naming_convention go_default_library $(GAZELLE_DIRS)
+	@# call gazelle with -args, which appends our arguments to those from the gazelle() rule
+	bazel run //:gazelle --verbose_failures --config=quiet -- -args -mode=$(GAZELLE_MODE) $(GAZELLE_DIRS)
 
-licenses:
+licenses: bazel
 	tools/licenses.sh
 
 antlr:

private/storage/db/BUILD.bazel

@@ -1,15 +1,7 @@
 load("//tools/lint:go.bzl", "go_library", "go_test")
 
-# Gazelle cannot deal with a select() in srcs, and neither can lint.
-# replace sqlite_mattn.go with sqlite_modernc.go in the list below if
-# you want to use the modernc implementation.
-# DO NOT remove the keep comment.
-# In the deps attribute, only one of the two sqlite libraries
-# is needed at any one time, but since Gazelle can't deal with it,
-# just leave both. It doesn't hurt.
 go_library(
     name = "go_default_library",
-    # keep
     srcs = [
         "doc.go",
         "errors.go",
@@ -24,7 +16,6 @@ go_library(
         "//pkg/private/common:go_default_library",
         "//pkg/private/prom:go_default_library",
         "//pkg/private/serrors:go_default_library",
-        "@com_github_mattn_go_sqlite3//:go_default_library",
         "@org_modernc_sqlite//:go_default_library",
     ],
 )

private/storage/db/sqlite_mattn.go

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// go:build (sqlite_mattn)
+// +build sqlite_mattn
+
 package db
 
 import (

private/storage/db/sqlite_modernc.go

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// go:build (sqlite_modernc)
+// +build sqlite_modernc
+
 package db
 
 import (