fix expression at runs-on: may be an array (fix #164)

ast.go

@@ -740,6 +740,8 @@ type Runner struct {
 	// Labels is list label names to select a runner to run a job. There are preset labels and user
 	// defined labels. Runner matching to the labels is selected.
 	Labels []*String
+	// Expression is a string when expression syntax ${{ }} is used for this section. Related issue is #164.
+	Expression *String
 }
 
 // WorkflowCallInput is a normal input for workflow call.

command.go

@@ -131,8 +131,8 @@ func (cmd *Command) Main(args []string) int {
 	flags := flag.NewFlagSet(args[0], flag.ContinueOnError)
 	flags.SetOutput(cmd.Stderr)
 	flags.Var(&ignorePats, "ignore", "Regular expression matching to error messages you want to ignore. This flag is repeatable")
-	flags.StringVar(&opts.Shellcheck, "shellcheck", "shellcheck", "Command name or file path of \"shellcheck\" external command. When empty, shellcheck integration will be disabled")
-	flags.StringVar(&opts.Pyflakes, "pyflakes", "pyflakes", "Command name or file path of \"pyflakes\" external command. When empty, pyflakes integration will be disabled")
+	flags.StringVar(&opts.Shellcheck, "shellcheck", "shellcheck", "Command name or file path of \"shellcheck\" external command. If empty, shellcheck integration will be disabled")
+	flags.StringVar(&opts.Pyflakes, "pyflakes", "pyflakes", "Command name or file path of \"pyflakes\" external command. If empty, pyflakes integration will be disabled")
 	flags.BoolVar(&opts.Oneline, "oneline", false, "Use one line per one error. Useful for reading error messages from programs")
 	flags.StringVar(&opts.Format, "format", "", "Custom template to format error messages in Go template syntax. See https://github.com/rhysd/actionlint/tree/main/docs/usage.md#format")
 	flags.StringVar(&opts.ConfigFile, "config-file", "", "File path to config file")

parse.go

@@ -130,6 +130,17 @@ func (p *parser) parseExpression(n *yaml.Node, expecting string) *String {
 	return newString(n)
 }
 
+func (p *parser) mayParseExpression(n *yaml.Node) *String {
+	if n.Tag != "!!str" {
+		return nil
+	}
+	s := strings.TrimSpace(n.Value)
+	if !strings.HasPrefix(s, "${{") || !strings.HasSuffix(s, "}}") || strings.Count(n.Value, "${{") != 1 || strings.Count(n.Value, "}}") != 1 {
+		return nil
+	}
+	return newString(n)
+}
+
 func (p *parser) parseString(n *yaml.Node, allowEmpty bool) *String {
 	if !p.checkString(n, allowEmpty) {
 		return &String{"", false, posAt(n)}
@@ -1101,8 +1112,12 @@ func (p *parser) parseJob(id *String, n *yaml.Node) *Job {
 				ret.Needs = p.parseStringSequence("needs", v, false, false)
 			}
 		case "runs-on":
-			labels := p.parseStringOrStringSequence("runs-on", v, false, false)
-			ret.RunsOn = &Runner{labels}
+			if expr := p.mayParseExpression(v); expr != nil {
+				ret.RunsOn = &Runner{nil, expr}
+			} else {
+				labels := p.parseStringOrStringSequence("runs-on", v, false, false)
+				ret.RunsOn = &Runner{labels, nil}
+			}
 			stepsOnlyKey = k
 		case "permissions":
 			ret.Permissions = p.parsePermissions(k.Pos, v)

process.go

@@ -76,7 +76,7 @@ func (proc *concurrentProcess) run(eg *errgroup.Group, exe string, args []string
 
 // wait waits all goroutines started by this concurrentProcess instance finish.
 func (proc *concurrentProcess) wait() {
-	proc.wg.Wait() // Wait for all gorotines completing to shutdown
+	proc.wg.Wait() // Wait for all goroutines completing to shutdown
 }
 
 // newCommandRunner creates new external command runner for given executable. The executable path

rule_expression.go

@@ -163,8 +163,18 @@ func (rule *RuleExpression) VisitJobPre(n *Job) error {
 	rule.checkStrings(n.Needs)
 
 	if n.RunsOn != nil {
-		for _, l := range n.RunsOn.Labels {
-			rule.checkString(l)
+		if n.RunsOn.Expression != nil {
+			ty := rule.checkOneExpression(n.RunsOn.Expression, "runner label at \"runs-on\" section")
+			switch ty.(type) {
+			case *ArrayType, StringType, AnyType:
+				// OK
+			default:
+				rule.errorf(n.RunsOn.Expression.Pos, "type of expression at \"runs-on\" must be string or array but found type %q", ty.String())
+			}
+		} else {
+			for _, l := range n.RunsOn.Labels {
+				rule.checkString(l)
+			}
 		}
 	}
 

rule_runner_label.go

@@ -112,8 +112,12 @@ func (rule *RuleRunnerLabel) VisitJobPre(n *Job) error {
 	}
 
 	rule.compats = map[runnerOSCompat]*String{}
-	for _, label := range n.RunsOn.Labels {
-		rule.checkLabelAndConflict(label, m)
+	if n.RunsOn.Expression != nil {
+		rule.checkLabelAndConflict(n.RunsOn.Expression, m)
+	} else {
+		for _, label := range n.RunsOn.Labels {
+			rule.checkLabelAndConflict(label, m)
+		}
 	}
 
 	rule.compats = nil // reset

testdata/ok/issue-164.yaml

@@ -0,0 +1,16 @@
+# https://github.com/rhysd/actionlint/issues/164
+
+on: push
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        include:
+          - msg: hello macos
+            host-labels: ["self-hosted", "macOS", "X64"]
+          - msg: hello linux
+            host-labels: ["self-hosted", "linux"]
+    runs-on: ${{ matrix.host-labels }}
+    steps:
+      - run: echo "${{ matrix.msg }}"