Reject invalid DSC resource-body pairings (#2286)

* Initial plan

* Fix DSC resource body detection edge cases

Co-authored-by: bergmeister <9250262+bergmeister@users.noreply.github.com>

* Optimize DSC separator detection

Co-authored-by: bergmeister <9250262+bergmeister@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: bergmeister <9250262+bergmeister@users.noreply.github.com>

Author: Copilot

Rules/AvoidAlias.cs

@@ -348,6 +348,12 @@ private ScriptBlockExpressionAst GetDscResourceBody(CommandAst cmdAst)
                         && bodyPipeline.PipelineElements.Count == 1
                         && bodyPipeline.PipelineElements[0] is CommandExpressionAst bodyExpression)
                     {
+                        if (HasSemicolonSeparator(pipeline, bodyPipeline)
+                            || bodyExpression.Redirections.Count != 0)
+                        {
+                            return null;
+                        }
+
                         return bodyExpression.Expression as ScriptBlockExpressionAst;
                     }
 
@@ -358,6 +364,26 @@ private ScriptBlockExpressionAst GetDscResourceBody(CommandAst cmdAst)
             return null;
         }
 
+        private bool HasSemicolonSeparator(Ast statement, Ast nextStatement)
+        {
+            int separatorStart = statement.Extent.EndOffset;
+            int separatorLength = nextStatement.Extent.StartOffset - separatorStart;
+            if (separatorLength <= 0)
+            {
+                return false;
+            }
+
+            string script = statement.Extent.EndScriptPosition.GetFullScript();
+            string separator = script.Substring(separatorStart, separatorLength);
+            if (separator.IndexOf(';') < 0)
+            {
+                return false;
+            }
+
+            Parser.ParseInput(separator, out Token[] tokens, out ParseError[] errors);
+            return tokens.Any(token => token.Kind == TokenKind.Semi);
+        }
+
         /// <summary>
         /// For a command like "gci -path c:", returns the extent of "gci" in the command
         /// </summary>

Tests/Rules/AvoidUsingAlias.tests.ps1

@@ -232,6 +232,30 @@ Configuration PackageTest {
                 $_.SuggestedCorrections[0].Text | Should -Be 'Get-Verb'
             }
         }
+
+        It "does not pair following-line blocks with commands when the block has redirections or a statement terminator intervenes" {
+            $target = @'
+{
+    gci .
+    {} > $null
+    gci .; {}
+}
+'@
+            $ast = [System.Management.Automation.Language.Parser]::ParseInput($target, [ref]$null, [ref]$null)
+            $body = $ast.EndBlock.Statements[0].PipelineElements[0].Expression.Copy()
+            $configuration = [System.Management.Automation.Language.ConfigurationDefinitionAst]::new(
+                $ast.Extent, $body, 'Resource',
+                [System.Management.Automation.Language.StringConstantExpressionAst]::new($ast.Extent, 'Test', 'BareWord'))
+            $rule = [Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.AvoidAlias]::new()
+
+            $violations = @($rule.AnalyzeScript($configuration, $null))
+
+            $violations.Count | Should -Be 2
+            $violations | ForEach-Object {
+                $_.Extent.Text | Should -Be 'gci'
+                $_.SuggestedCorrections[0].Text | Should -Be 'Get-ChildItem'
+            }
+        }
     }
 
     Context "Settings file provides allowlist" {