switch to final Go 1.20 release and re-enable gotip in CI

Go master, the upcoming Go 1.21, has had its merge window open for over
two weeks at this point, and it seems calmer at this point.

ALso update staticcheck to its latest release, which supports Go 1.20.

.github/workflows/test.yml

@@ -22,7 +22,7 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.19.x, 1.20.0-rc.3]
+        go-version: [1.19.x, 1.20.x]
         # TODO: revert to macos-latest once we figure out https://github.com/burrowers/garble/issues/609.
         os: [ubuntu-latest, macos-11, windows-latest]
     runs-on: ${{ matrix.os }}
@@ -47,20 +47,20 @@ jobs:
     # Static checks from this point forward. Only run on one Go version and on
     # Linux, since it's the fastest platform, and the tools behave the same.
     - name: Test third-party project builds
-      if: matrix.os == 'ubuntu-latest' && matrix.go-version == '1.19.x'
+      if: matrix.os == 'ubuntu-latest' && matrix.go-version == '1.20.x'
       run: |
         go install
         ./scripts/check-third-party.sh
-    - if: matrix.os == 'ubuntu-latest' && matrix.go-version == '1.19.x'
+    - if: matrix.os == 'ubuntu-latest' && matrix.go-version == '1.20.x'
       run: ./scripts/crlf-test.sh
-    - if: matrix.os == 'ubuntu-latest' && matrix.go-version == '1.19.x'
+    - if: matrix.os == 'ubuntu-latest' && matrix.go-version == '1.20.x'
       run: diff <(echo -n) <(gofmt -d .)
-    - if: matrix.os == 'ubuntu-latest' && matrix.go-version == '1.19.x'
+    - if: matrix.os == 'ubuntu-latest' && matrix.go-version == '1.20.x'
       run: go vet ./...
-    - if: matrix.os == 'ubuntu-latest' && matrix.go-version == '1.19.x'
+    - if: matrix.os == 'ubuntu-latest' && matrix.go-version == '1.20.x'
       uses: dominikh/staticcheck-action@v1
       with:
-        version: "2022.1.3"
+        version: "2023.1"
         install-go: false
 
   # We don't care about GOARCH=386 particularly,
@@ -74,18 +74,17 @@ jobs:
     steps:
     - uses: actions/setup-go@v3
       with:
-        go-version: 1.19.x
+        go-version: 1.20.x
     - uses: actions/checkout@v3
     - name: Test
       run: go test -timeout=15m ./...
 
   test-gotip:
-    if: false # let tip for 1.21 settle a bit
     runs-on: ubuntu-latest
     steps:
     - name: Install Go
       env:
-        GO_COMMIT: cb07765045aed5104a3df31507564ac99e6ddce8 # 2022-12-13
+        GO_COMMIT: 6d4de4e386cd9e4ec32937ab2d4f79317db461cd # 2023-01-31
       run: |
         cd $HOME
         mkdir $HOME/gotip
@@ -93,7 +92,7 @@ jobs:
 
         wget -O gotip.tar.gz https://go.googlesource.com/go/+archive/${GO_COMMIT}.tar.gz
         tar -xf gotip.tar.gz
-        echo "devel go1.20-${GO_COMMIT}" >VERSION
+        echo "devel go1.21-${GO_COMMIT}" >VERSION
 
         cd src
         ./make.bash

main.go

@@ -263,7 +263,7 @@ var toolchainVersionSemver string
 func goVersionOK() bool {
 	const (
 		minGoVersionSemver = "v1.19.0"
-		suggestedGoVersion = "1.19.x"
+		suggestedGoVersion = "1.20.x"
 	)
 
 	// rxVersion looks for a version like "go1.2" or "go1.2.3"

testdata/script/goversion.txtar

@@ -7,18 +7,18 @@ env PATH=${WORK}/.bin${:}${PATH}
 # An empty go version.
 env TOOLCHAIN_GOVERSION=''
 ! garble build
-stderr 'Go version is too old; please upgrade to Go 1\.19\.x or newer'
+stderr 'Go version is too old; please upgrade to Go 1\.20\.x or newer'
 
 # We should error on a devel version that's too old.
 # Note that they lacked the "goN.M-" prefix.
 env TOOLCHAIN_GOVERSION='devel +afb5fca Sun Aug 07 00:00:00 2020 +0000'
 ! garble build
-stderr 'Go version is too old; please upgrade to Go 1\.19\.x or newer'
+stderr 'Go version is too old; please upgrade to Go 1\.20\.x or newer'
 
 # Another form of old version; with an old "goN.M-" prefix.
 env TOOLCHAIN_GOVERSION='devel go1.15-afb5fca Sun Aug 07 00:00:00 2020 +0000'
 ! garble build
-stderr 'Go version "devel go1\.15-.*2020.*" is too old; please upgrade to Go 1\.19\.x'
+stderr 'Go version "devel go1\.15-.*2020.*" is too old; please upgrade to Go 1\.20\.x'
 
 # A current devel version should be fine.
 # Note that we don't look at devel version timestamps.
@@ -30,7 +30,7 @@ stderr 'mocking the real build'
 # We should error on a stable version that's too old.
 env TOOLCHAIN_GOVERSION='go1.14'
 ! garble build
-stderr 'Go version "go1\.14" is too old; please upgrade to Go 1\.19\.x or newer'
+stderr 'Go version "go1\.14" is too old; please upgrade to Go 1\.20\.x or newer'
 
 # We should accept a future stable version.
 # Note that we need to bump the version of Go that supposedly built it, too.