scripts: start checking google.golang.org/protobuf

The current garble release is able to obfuscate it with Go 1.20.

While here, re-generate all files to use "go 1.20" directives,
and add a TODO about also testing binary builds for each project.

See #600.

scripts/cached_modfiles/github.com_andybalholm_brotli_v1.0.4.mod

@@ -1,5 +1,5 @@
 module test
 
-go 1.19
+go 1.20
 
 require github.com/andybalholm/brotli v1.0.4 // indirect

scripts/cached_modfiles/github.com_samber_lo_v1.21.0.mod

@@ -1,6 +1,6 @@
 module test
 
-go 1.19
+go 1.20
 
 require (
 	github.com/samber/lo v1.21.0 // indirect

scripts/cached_modfiles/golang.zx2c4.com_wireguard_0.0.20220316.mod

@@ -1,6 +1,6 @@
 module test
 
-go 1.19
+go 1.20
 
 require (
 	golang.org/x/crypto v0.0.0-20220315160706-3147a52a75dd // indirect

scripts/cached_modfiles/google.golang.org_protobuf_v1.28.1.mod

@@ -0,0 +1,10 @@
+module test
+
+go 1.20
+
+require (
+	github.com/golang/protobuf v1.5.0 // indirect
+	github.com/google/go-cmp v0.5.5 // indirect
+	golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 // indirect
+	google.golang.org/protobuf v1.28.1 // indirect
+)

scripts/cached_modfiles/google.golang.org_protobuf_v1.28.1.sum

@@ -0,0 +1,9 @@
+github.com/golang/protobuf v1.5.0 h1:LUVKkCeviFUMKqHa4tXIIij/lbhnMbP7Fn5wKdKkRh4=
+github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
+github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
+github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
+google.golang.org/protobuf v1.28.1 h1:d0NfwRgPtno5B1Wa6L2DAG+KivqkdutMf1UhdNx175w=
+google.golang.org/protobuf v1.28.1/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=

scripts/check-third-party.sh

@@ -13,10 +13,15 @@
 # For example, a good example of a project to add is one that has unearthed
 # multiple bugs in garble before, such as Protobuf.
 # Also remember that the standard library already provides significant cover.
+#
+# TODO: note that this script only catches errors when compiling packages,
+# but it will not catch problems that may only arise at link time,
+# such as go:linknames which are not properly obfuscated.
+# Consider building and linking relevant main packages from each project,
+# such as ./cmd/protoc-gen-go for protobuf.
 modules=(
 	# Protobuf helps cover encoding libraries and reflection.
-	# TODO: currently fails.
-	# google.golang.org/protobuf v1.28.0
+	google.golang.org/protobuf v1.28.1
 
 	# Wireguard helps cover networking and cryptography.
 	golang.zx2c4.com/wireguard 0.0.20220316