lib/goanalysis: package to complement "go vet"

Package goanalysis implement go static analysis using
[Analyzer] that are not included in the default "go vet", but included in
the [passes] directory, including: fieldalignment, nilness,
reflectvaluecompare, shadow, sortslice, unusedwrite, and waitgroup.

This package is not mean to be imported directly by other package
except main, like we have in [cmd/gocheck].

The rest (and previous) of the changes are affect running gocheck on it.

6 files changed, 71 insertions, 4 deletions

diff --git a/.gitignore b/.gitignore
index 43d611bb..03d6f870 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,6 +19,7 @@
 /_bin/bcrypt
 /_bin/emaildecode
 /_bin/epoch
+/_bin/gocheck
 /_bin/gofmtcomment
 /_bin/hexo
 /_bin/httpdfs
diff --git a/Makefile b/Makefile
index af994b5a..6b032399 100644
--- a/Makefile
+++ b/Makefile
@@ -36,8 +36,7 @@ test.prof:
 	go test -race -timeout=1m -cpuprofile $(CPU_PROF) -memprofile $(MEM_PROF) ./...
 
 lint:
-	-fieldalignment ./...
-	-shadow ./...
+	go run ./cmd/gocheck ./...
 	go vet ./...
 
 $(CIIGO):
diff --git a/cmd/gocheck/main.go b/cmd/gocheck/main.go
new file mode 100644
index 00000000..cb9d3787
--- /dev/null
+++ b/cmd/gocheck/main.go
@@ -0,0 +1,17 @@
+// SPDX-FileCopyrightText: 2024 M. Shulhan <ms@kilabit.info>
+//
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Program gocheck implement go static analysis using [Analyzer] that are not
+// included in the default go vet.
+// See package [lib/goanalysis] for more information.
+//
+// [Analyzer]: https://pkg.go.dev/golang.org/x/tools/go/analysis#hdr-Analyzer
+// [lib/goanalysis]: https://pkg.go.dev/git.sr.ht/~shulhan/pakakeh.go/lib/goanalysis/
+package main
+
+import "git.sr.ht/~shulhan/pakakeh.go/lib/goanalysis"
+
+func main() {
+	goanalysis.Check()
+}
diff --git a/lib/binary/apo_footer.go b/lib/binary/apo_footer.go
index 7e6670c1..17d7c08f 100644
--- a/lib/binary/apo_footer.go
+++ b/lib/binary/apo_footer.go
@@ -17,7 +17,7 @@ type apoFooter struct {
 
 func (foot *apoFooter) WriteTo(w io.Writer) (n int64, err error) {
 	var nidx int64 = int64(len(foot.idxMetaOff))
-	_ = binary.Write(w, binary.BigEndian, nidx)
+	err = binary.Write(w, binary.BigEndian, nidx)
 	if err != nil {
 		return 0, err
 	}
diff --git a/lib/crypto/crypto_test.go b/lib/crypto/crypto_test.go
index b99ff4a4..a90f42ca 100644
--- a/lib/crypto/crypto_test.go
+++ b/lib/crypto/crypto_test.go
@@ -173,7 +173,7 @@ func TestLoadPrivateKeyInteractive(t *testing.T) {
 
 		_, ok = pkey.(*rsa.PrivateKey)
 		if !ok {
-			test.Assert(t, c.desc+` cast to *rsa.PrivateKey`, c.expError, err.Error())
+			t.Fatalf(`expecting pkey is *rsa.PrivateKey, got %T`, pkey)
 			continue
 		}
 	}
diff --git a/lib/goanalysis/goanalysis.go b/lib/goanalysis/goanalysis.go
new file mode 100644
index 00000000..25f13295
--- /dev/null
+++ b/lib/goanalysis/goanalysis.go
@@ -0,0 +1,50 @@
+// SPDX-FileCopyrightText: 2024 M. Shulhan <ms@kilabit.info>
+//
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Package goanalysis implement go static analysis using
+// [Analyzer] that are not included in the default "go vet", but included in
+// the [passes] directory, including
+//
+//   - fieldalignment: detects structs that would use less memory if their
+//     fields were sorted.
+//   - nilness: inspects the control-flow graph of an SSA function and reports
+//     errors such as nil pointer dereferences and degenerate nil pointer
+//     comparisons.
+//   - reflectvaluecompare: checks for accidentally using == or
+//     [reflect.DeepEqual] to compare reflect.Value values.
+//   - shadow: checks for shadowed variables.
+//   - sortslice: checks for calls to sort.Slice that do not use a slice type
+//     as first argument.
+//   - unusedwrite: checks for unused writes to the elements of a struct or
+//     array object.
+//   - waitgroup: detects simple misuses of sync.WaitGroup.
+//
+// [Analyzer]: https://pkg.go.dev/golang.org/x/tools/go/analysis#hdr-Analyzer
+// [passes]: https://pkg.go.dev/golang.org/x/tools/go/analysis/passes
+package goanalysis
+
+import (
+	"golang.org/x/tools/go/analysis/multichecker"
+	"golang.org/x/tools/go/analysis/passes/fieldalignment"
+	"golang.org/x/tools/go/analysis/passes/nilness"
+	"golang.org/x/tools/go/analysis/passes/reflectvaluecompare"
+	"golang.org/x/tools/go/analysis/passes/shadow"
+	"golang.org/x/tools/go/analysis/passes/sortslice"
+	"golang.org/x/tools/go/analysis/passes/unusedwrite"
+	"golang.org/x/tools/go/analysis/passes/waitgroup"
+)
+
+// Check run the static analysis.
+// This function is not mean to be call directly, but used in the main func.
+func Check() {
+	multichecker.Main(
+		fieldalignment.Analyzer,
+		nilness.Analyzer,
+		reflectvaluecompare.Analyzer,
+		shadow.Analyzer,
+		sortslice.Analyzer,
+		unusedwrite.Analyzer,
+		waitgroup.Analyzer,
+	)
+}