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Only suggest StringBuilder for >3 string concats (#26) #38

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Mar 19, 2018
Merged

Only suggest StringBuilder for >3 string concats (#26) #38

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5ab97f4
Only suggest StringBuilder for >3 string concats (#26)
edespong Dec 13, 2017
c0f58de
Merge with master
edespong Mar 17, 2018
ac625b5
Fixed errors after merge
edespong Mar 17, 2018
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35 changes: 9 additions & 26 deletions ClrHeapAllocationsAnalyzer.Test/ConcatenationAllocationAnalyzerTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,37 +7,20 @@
namespace ClrHeapAllocationsAnalyzer.Test
{
[TestClass]
public class ConcatenationAllocationAnalyzerTests : AllocationAnalyzerTests
{
public class ConcatenationAllocationAnalyzerTests : AllocationAnalyzerTests {
[TestMethod]
public void ConcatenationAllocation_Basic()
{
var sampleProgram =
@"using System;

var withBoxing = 5.ToString() + ':' + 8.ToString(); // Boxing on ':'
var withoutBoxing = 5.ToString() + "":"" + 8.ToString();
";
public void ConcatenationAllocation_Basic() {
var snippet0 = @"string s0 = ""hello"" + 0.ToString() + ""world"" + 1.ToString();";
var snippet1 = @"string s2 = ""ohell"" + 2.ToString() + ""world"" + 3.ToString() + 4.ToString();";

var analyser = new ConcatenationAllocationAnalyzer();
var info = ProcessCode(analyser, sampleProgram, ImmutableArray.Create(SyntaxKind.AddExpression, SyntaxKind.AddAssignmentExpression));

Assert.AreEqual(1, info.Allocations.Count(d => d.Id == ConcatenationAllocationAnalyzer.ValueTypeToReferenceTypeInAStringConcatenationRule.Id));
Assert.AreEqual(4, info.Allocations.Count(d => d.Id == ConcatenationAllocationAnalyzer.StringConcatenationAllocationRule.Id));
var info0 = ProcessCode(analyser, snippet0, ImmutableArray.Create(SyntaxKind.AddExpression, SyntaxKind.AddAssignmentExpression));
var info1 = ProcessCode(analyser, snippet1, ImmutableArray.Create(SyntaxKind.AddExpression, SyntaxKind.AddAssignmentExpression));

//### CODE ### 5.ToString() + ':' + 8.ToString()
//*** Diagnostic: (9,45): warning HeapAnalyzerBoxingRule: Value type (char) is being boxed to a reference type for a string concatenation.
AssertEx.ContainsDiagnostic(info.Allocations, id: ConcatenationAllocationAnalyzer.ValueTypeToReferenceTypeInAStringConcatenationRule.Id, line: 3, character: 33);
// Diagnostic: (9,43): warning HeapAnalyzerStringConcatRule: Considering using StringBuilder
AssertEx.ContainsDiagnostic(info.Allocations, id: ConcatenationAllocationAnalyzer.StringConcatenationAllocationRule.Id, line: 3, character: 31);
// Diagnostic: (9,49): warning HeapAnalyzerStringConcatRule: Considering using StringBuilder
AssertEx.ContainsDiagnostic(info.Allocations, id: ConcatenationAllocationAnalyzer.StringConcatenationAllocationRule.Id, line: 3, character: 37);
Assert.AreEqual(0, info0.Allocations.Count(d => d.Id == ConcatenationAllocationAnalyzer.StringConcatenationAllocationRule.Id));
Assert.AreEqual(1, info1.Allocations.Count(d => d.Id == ConcatenationAllocationAnalyzer.StringConcatenationAllocationRule.Id));

//### CODE ### 5.ToString() + ":" + 8.ToString()
// Diagnostic: (10,46): warning HeapAnalyzerStringConcatRule: Considering using StringBuilder
AssertEx.ContainsDiagnostic(info.Allocations, id: ConcatenationAllocationAnalyzer.StringConcatenationAllocationRule.Id, line: 4, character: 34);
// Diagnostic: (10,52): warning HeapAnalyzerStringConcatRule: Considering using StringBuilder
AssertEx.ContainsDiagnostic(info.Allocations, id: ConcatenationAllocationAnalyzer.StringConcatenationAllocationRule.Id, line: 4, character: 40);
AssertEx.ContainsDiagnostic(info1.Allocations, id: ConcatenationAllocationAnalyzer.StringConcatenationAllocationRule.Id, line: 1, character: 13);
}

[TestMethod]
Expand Down
4 changes: 1 addition & 3 deletions ClrHeapAllocationsAnalyzer.Test/StackOverflowAnswerTests.cs
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Expand Up @@ -82,11 +82,9 @@ public void Non_constant_value_types_in_CSharp_string_concatenation()
string s1 = ""char value will box"" + c;";
var analyser = new ConcatenationAllocationAnalyzer();
var info = ProcessCode(analyser, @script, ImmutableArray.Create(SyntaxKind.AddExpression, SyntaxKind.AddAssignmentExpression));
Assert.AreEqual(2, info.Allocations.Count);
Assert.AreEqual(1, info.Allocations.Count);
//Diagnostic: (2,53): warning HeapAnalyzerBoxingRule: Value type (char) is being boxed to a reference type for a string concatenation.
AssertEx.ContainsDiagnostic(info.Allocations, ConcatenationAllocationAnalyzer.ValueTypeToReferenceTypeInAStringConcatenationRule.Id, line: 2, character: 53);
//Diagnostic: (2,51): warning HeapAnalyzerStringConcatRule: Considering using StringBuilder
AssertEx.ContainsDiagnostic(info.Allocations, ConcatenationAllocationAnalyzer.StringConcatenationAllocationRule.Id, line: 2, character: 51);
}

[TestMethod]
Expand Down
10 changes: 8 additions & 2 deletions ClrHeapAllocationsAnalyzer/ConcatenationAllocationAnalyzer.cs
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Expand Up @@ -33,6 +33,7 @@ private static void AnalyzeNode(SyntaxNodeAnalysisContext context)
string filePath = node.SyntaxTree.FilePath;
var binaryExpressions = node.DescendantNodesAndSelf().OfType<BinaryExpressionSyntax>().Reverse(); // need inner most expressions

int stringConcatenationCount = 0;
foreach (var binaryExpression in binaryExpressions)
{
if (binaryExpression.Left == null || binaryExpression.Right == null)
Expand All @@ -55,10 +56,15 @@ private static void AnalyzeNode(SyntaxNodeAnalysisContext context)
// regular string allocation
if (left.Type?.SpecialType == SpecialType.System_String || right.Type?.SpecialType == SpecialType.System_String)
{
reportDiagnostic(Diagnostic.Create(StringConcatenationAllocationRule, binaryExpression.OperatorToken.GetLocation(), EmptyMessageArgs));
HeapAllocationAnalyzerEventSource.Logger.StringConcatenationAllocation(filePath);
stringConcatenationCount++;
}
}

if (stringConcatenationCount > 3)
{
reportDiagnostic(Diagnostic.Create(StringConcatenationAllocationRule, node.GetLocation(), EmptyMessageArgs));
HeapAllocationAnalyzerEventSource.Logger.StringConcatenationAllocation(filePath);
}
}

private static void CheckForTypeConversion(ExpressionSyntax expression, TypeInfo typeInfo, Action<Diagnostic> reportDiagnostic, string filePath)
Expand Down