Collect suppression declarations in a single AST traversal

Engine/Helper.cs

@@ -1198,24 +1198,28 @@ public Dictionary<string, List<RuleSuppression>> GetRuleSuppression(Ast ast)
                 ruleSuppressionList.AddRange(RuleSuppression.GetSuppressions(sbAst.ParamBlock.Attributes, sbAst.Extent.StartOffset, sbAst.Extent.EndOffset, sbAst));
             }
 
+            // Walk the tree once, retaining the existing function/class/configuration processing order.
+            var declarationAsts = ast.FindAll(item => item is FunctionDefinitionAst
+                || item is TypeDefinitionAst || item is ConfigurationDefinitionAst, true).ToArray();
+
             // Get rule suppression from functions
-            IEnumerable<FunctionDefinitionAst> funcAsts = ast.FindAll(item => item is FunctionDefinitionAst, true).Cast<FunctionDefinitionAst>();
+            IEnumerable<FunctionDefinitionAst> funcAsts = declarationAsts.OfType<FunctionDefinitionAst>();
 
             foreach (var funcAst in funcAsts)
             {
                 ruleSuppressionList.AddRange(GetSuppressionsFunction(funcAst));
             }
 
             // Get rule suppression from classes
-            IEnumerable<TypeDefinitionAst> typeAsts = ast.FindAll(item => item is TypeDefinitionAst, true).Cast<TypeDefinitionAst>();
+            IEnumerable<TypeDefinitionAst> typeAsts = declarationAsts.OfType<TypeDefinitionAst>();
 
             foreach (var typeAst in typeAsts)
             {
                 ruleSuppressionList.AddRange(GetSuppressionsClass(typeAst));
             }
 
             // Get rule suppression from configuration definitions
-            IEnumerable<ConfigurationDefinitionAst> configDefAsts = ast.FindAll(item => item is ConfigurationDefinitionAst, true).Cast<ConfigurationDefinitionAst>();
+            IEnumerable<ConfigurationDefinitionAst> configDefAsts = declarationAsts.OfType<ConfigurationDefinitionAst>();
 
             foreach (var configDefAst in configDefAsts)
             {

Tests/Engine/RuleSuppressionDeclaration.tests.ps1

@@ -0,0 +1,32 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+Describe 'Suppressions on interleaved declarations' {
+    It 'suppresses function and class bodies without suppressing a call outside them' {
+        $definition = @'
+function First {
+    [System.Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSAvoidUsingInvokeExpression', '')]
+    param()
+    Invoke-Expression 'first'
+}
+[System.Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSAvoidUsingInvokeExpression', '')]
+class SuppressedClass {
+    [void] Emit() {
+        Invoke-Expression 'class'
+    }
+}
+function Last {
+    [System.Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSAvoidUsingInvokeExpression', '')]
+    param()
+    Invoke-Expression 'last'
+}
+Invoke-Expression 'outside'
+'@
+        $violations = @(Invoke-ScriptAnalyzer -ScriptDefinition $definition -IncludeRule PSAvoidUsingInvokeExpression)
+        $violations.Count | Should -Be 1
+        $violations[0].Extent.Text | Should -BeExactly "Invoke-Expression 'outside'"
+
+        $suppressed = @(Invoke-ScriptAnalyzer -ScriptDefinition $definition -IncludeRule PSAvoidUsingInvokeExpression -SuppressedOnly)
+        $suppressed.Count | Should -Be 3
+    }
+}