refactor: Use Go 1.20 (#643)

Fixes #589

---------

Signed-off-by: Ian Lewis <ianlewis@google.com>

.github/workflows/pre-submit.cli.yml

@@ -20,7 +20,7 @@ jobs:
       - name: setup-go
         uses: actions/setup-go@fac708d6674e30b6ba41289acaab6d4b75aa0753 # v4.0.1
         with:
-          go-version: "1.18"
+          go-version-file: "go.mod"
 
       - name: Save event name
         env:

.github/workflows/pre-submit.e2e.yml

@@ -18,7 +18,7 @@ jobs:
       - name: setup-go
         uses: actions/setup-go@fac708d6674e30b6ba41289acaab6d4b75aa0753 # v4.0.1
         with:
-          go-version: "1.18"
+          go-version-file: "__THIS_REPO__/go.mod"
 
       - name: Build verifier at HEAD
         working-directory: __THIS_REPO__

.github/workflows/pre-submit.lint.yml

@@ -13,10 +13,10 @@ jobs:
       - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
       - uses: actions/setup-go@fac708d6674e30b6ba41289acaab6d4b75aa0753 # v4.0.1
         with:
-          go-version: "1.18"
+          go-version-file: "go.mod"
       - env:
-          GOLANGCI_LINT_VERSION: "1.52.2"
-          GOLANGCI_LINT_CHECKSUM: "c9cf72d12058a131746edd409ed94ccd578fbd178899d1ed41ceae3ce5f54501"
+          GOLANGCI_LINT_VERSION: "1.53.2"
+          GOLANGCI_LINT_CHECKSUM: "2298f73b9bc03b88b91fee06c5d519fc7f9d7f328e2c388615bbd7e85a9d6cae"
         run: |
           set -euo pipefail
 

.github/workflows/release.yml

@@ -51,7 +51,7 @@ jobs:
       contents: write # For asset uploads.
     uses: slsa-framework/slsa-github-generator/.github/workflows/builder_go_slsa3.yml@v1.7.0
     with:
-      go-version: 1.18
+      go-version-file: "go.mod"
       config-file: .slsa-goreleaser/${{matrix.os}}-${{matrix.arch}}.yml
       compile-builder: true
       evaluated-envs: "VERSION:${{needs.args.outputs.version}}"

.golangci.yml

@@ -81,6 +81,88 @@ linters:
     # TODO(https://github.com/slsa-framework/slsa-verifier/issues/363): Restore linter
     # - wrapcheck
 linters-settings:
+  depguard:
+    rules:
+      global:
+        files:
+          - $all
+          - "!$test"
+          - "!**/experimental/**"
+
+          # This is an exception for the existing code.
+          # TODO(#642): Don't allow go-cmp in non-test code.
+          - "!**/verifiers/internal/gcb/provenance.go"
+        allow:
+          - $gostd
+
+          # Approved orgs.
+          - "github.com/slsa-framework"
+          - "github.com/in-toto"
+          - "github.com/sigstore"
+          - "github.com/secure-systems-lab"
+          - "github.com/go-openapi"
+
+          # Approved packages.
+          - "sigs.k8s.io/release-utils/version"
+          - "github.com/spf13/cobra" # For CLI
+          - "github.com/docker/go/canonical/json" # For canonical json.
+          - "github.com/google/go-containerregistry" # For interacting with container registries.
+        deny:
+          - pkg: "reflect"
+            desc: Please don't use reflect package
+          - pkg: "unsafe"
+            desc: Please don't use unsafe package
+
+      test:
+        files:
+          - "$test"
+          # - "!**/experimental/**"
+          # This is an exception for the existing code.
+          # TODO(#642): Don't allow go-cmp in non-test code.
+          - "!**/verifiers/internal/gcb/provenance.go"
+          # NOTE: test code is allowed to use github.com/google/go-cmp (there is no
+          #       deny for it) but non-test code is not.
+        allow:
+          - $gostd
+
+          # Approved orgs.
+          - "github.com/slsa-framework"
+          - "github.com/in-toto"
+          - "github.com/sigstore"
+          - "github.com/secure-systems-lab"
+          - "github.com/go-openapi"
+
+          # Approved packages.
+          - "sigs.k8s.io/release-utils/version"
+          - "github.com/spf13/cobra" # For CLI
+          - "github.com/docker/go/canonical/json" # For canonical json.
+          - "github.com/google/go-containerregistry" # For interacting with container registries.
+
+          # Allowed in test code.
+          - "github.com/google/go-cmp"
+        deny:
+          - pkg: "reflect"
+            desc: Please don't use reflect package
+          - pkg: "unsafe"
+            desc: Please don't use unsafe package
+
+      experimental:
+        files:
+          - "**/experimental/**/*.go"
+        allow:
+          - $gostd
+
+          # Approved orgs.
+          - "github.com/slsa-framework"
+
+          # Allowed in experimental.
+          - "github.com/gorilla/mux"
+        deny:
+          - pkg: "reflect"
+            desc: Please don't use reflect package
+          - pkg: "unsafe"
+            desc: Please don't use unsafe package
+
   errcheck:
     check-type-assertions: true
     check-blank: true

go.mod

@@ -1,6 +1,6 @@
 module github.com/slsa-framework/slsa-verifier/v2
 
-go 1.18
+go 1.20
 
 require (
 	github.com/docker/go v1.5.1-1