narrow synchronized region in pyflakes rule

Author: rhysd

rule_pyflakes.go

@@ -126,8 +126,6 @@ func (rule *RulePyflakes) runPyflakes(src string, pos *Pos) {
 			return nil
 		}
 
-		rule.mu.Lock()
-		defer rule.mu.Unlock()
 		for len(stdout) > 0 {
 			if stdout, err = rule.parseNextError(stdout, pos); err != nil {
 				return err
@@ -157,7 +155,11 @@ func (rule *RulePyflakes) parseNextError(stdout []byte, pos *Pos) ([]byte, error
 	} else {
 		return nil, fmt.Errorf("error message from pyflakes does not end with \\n nor \\r\\n while checking script at %s. output: %q", pos, stdout)
 	}
+
+	// This method needs to be thread-safe since concurrentProcess.run calls its callback in a different goroutine.
+	rule.mu.Lock()
 	rule.Errorf(pos, "pyflakes reported issue in this script: %s", msg)
+	rule.mu.Unlock()
 
 	return b, nil
 }

rule_pyflakes_test.go

@@ -13,36 +13,36 @@ func TestRulePyflakesDetectPythonShell(t *testing.T) {
 		step     string // Shell name set at 'shell' in Step node
 	}{
 		{
-			what: "no default shell",
+			what:     "no default shell",
 			isPython: false,
 		},
 		{
-			what: "workflow default",
+			what:     "workflow default",
 			isPython: true,
 			workflow: "python",
 		},
 		{
-			what: "job default",
+			what:     "job default",
 			isPython: true,
-			job: "python",
+			job:      "python",
 		},
 		{
-			what: "step shell",
+			what:     "step shell",
 			isPython: true,
-			step: "python",
+			step:     "python",
 		},
 		{
-			what: "custom shell",
+			what:     "custom shell",
 			isPython: true,
 			workflow: "python {0}",
 		},
 		{
-			what: "other shell",
+			what:     "other shell",
 			isPython: false,
 			workflow: "pwsh",
 		},
 		{
-			what: "other custom shell",
+			what:     "other custom shell",
 			isPython: false,
 			workflow: "bash -e {0}",
 		},

testdata/ok/shellcheck_step_shell.yaml

@@ -13,4 +13,4 @@ jobs:
       # This causes SC1001 if `shell:` is not set explicitly
       - run: cat xxx\yyy.txt
         if: ${{ matrix.os == 'windows-latest' }}
-        shell: 'python {0}'
+        shell: 'pwsh {0}'