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Fix modification of readonly locals through ref fields (#74255)
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* Fix modification of readonly locals through ref fields

* Extend tests

* Improve check

* Add query tests
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@jjonescz
jjonescz authored Jul 10, 2024
1 parent 8e69275 commit 28f0ccf
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Showing 4 changed files with 569 additions and 0 deletions.
1 change: 1 addition & 0 deletions src/Compilers/CSharp/Portable/BoundTree/Constructors.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,7 @@ private static bool NeedsByValueFieldAccess(BoundExpression? receiver, FieldSymb
{
if (fieldSymbol.IsStatic ||
!fieldSymbol.ContainingType.IsValueType ||
fieldSymbol.RefKind != RefKind.None ||
receiver == null) // receiver may be null in error cases
{
return false;
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249 changes: 249 additions & 0 deletions src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenForEachTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5327,5 +5327,254 @@ public static class Extensions
}";
CompileAndVerify(source, parseOptions: TestOptions.Regular9, expectedOutput: "123123");
}

[Theory, CombinatorialData, WorkItem("https://github.com/dotnet/roslyn/issues/73741")]
public void MutatingThroughRefFields_01(
[CombinatorialValues("ref", "")] string eRef,
[CombinatorialValues("readonly", "")] string vReadonly)
{
var source = $$"""
using System;
V[] arr = new V[3];
foreach (var r in new E(arr))
{
r.V.F++;
}
foreach (var v in arr) Console.Write(v.F);
{{eRef}} struct E(V[] arr)
{
int i;
public E GetEnumerator() => this;
public R Current => new(ref arr[i - 1]);
public bool MoveNext() => i++ < arr.Length;
}
ref struct R(ref V v)
{
public {{vReadonly}} ref V V = ref v;
}
struct V
{
public int F;
}
""";
CompileAndVerify(source, targetFramework: TargetFramework.Net70,
verify: Verification.Fails,
expectedOutput: ExecutionConditionUtil.IsDesktop ? null : "111").VerifyDiagnostics();
}

[Theory, CombinatorialData, WorkItem("https://github.com/dotnet/roslyn/issues/73741")]
public void MutatingThroughRefFields_02(
[CombinatorialValues("ref", "")] string eRef,
[CombinatorialValues("readonly", "")] string vReadonly)
{
var source = $$"""
using System;
V[] arr = new V[3];
foreach (var r in new E(arr))
{
r.V.F += 2;
}
foreach (var v in arr) Console.Write(v.F);
{{eRef}} struct E(V[] arr)
{
int i;
public E GetEnumerator() => this;
public R Current => new(ref arr[i - 1]);
public bool MoveNext() => i++ < arr.Length;
}
ref struct R(ref V v)
{
public {{vReadonly}} ref V V = ref v;
}
struct V
{
public int F;
}
""";
CompileAndVerify(source, targetFramework: TargetFramework.Net70,
verify: Verification.Fails,
expectedOutput: ExecutionConditionUtil.IsDesktop ? null : "222").VerifyDiagnostics();
}

[Theory, CombinatorialData, WorkItem("https://github.com/dotnet/roslyn/issues/73741")]
public void MutatingThroughRefFields_03(
[CombinatorialValues("ref", "")] string eRef,
[CombinatorialValues("readonly", "")] string vReadonly)
{
var source = $$"""
using System;
V[] arr = new V[3];
foreach (var r in new E(arr))
{
r.V.S.Inc();
}
foreach (var v in arr) Console.Write(v.S.F);
{{eRef}} struct E(V[] arr)
{
int i;
public E GetEnumerator() => this;
public R Current => new(ref arr[i - 1]);
public bool MoveNext() => i++ < arr.Length;
}
ref struct R(ref V v)
{
public {{vReadonly}} ref V V = ref v;
}
struct V
{
public S S;
}
struct S
{
public int F;
public void Inc() => F++;
}
""";
CompileAndVerify(source, targetFramework: TargetFramework.Net70,
verify: Verification.Fails,
expectedOutput: ExecutionConditionUtil.IsDesktop ? null : "111").VerifyDiagnostics();
}

[Theory, CombinatorialData, WorkItem("https://github.com/dotnet/roslyn/issues/73741")]
public void MutatingThroughRefFields_04(
[CombinatorialValues("ref", "")] string eRef,
[CombinatorialValues("readonly", "")] string vReadonly)
{
var source = $$"""
using System;
V[] arr = new V[3];
foreach (var r in new E(arr))
{
r.V.F++;
}
foreach (var v in arr) Console.Write(v.F);
{{eRef}} struct E(V[] arr)
{
int i;
public E GetEnumerator() => this;
public R Current => new(ref arr[i - 1]);
public bool MoveNext() => i++ < arr.Length;
}
ref struct R(ref V v)
{
public {{vReadonly}} ref readonly V V = ref v;
}
struct V
{
public int F;
}
""";
CreateCompilation(source, targetFramework: TargetFramework.Net70).VerifyDiagnostics(
// (7,5): error CS8332: Cannot assign to a member of field 'V' or use it as the right hand side of a ref assignment because it is a readonly variable
// r.V.F++;
Diagnostic(ErrorCode.ERR_AssignReadonlyNotField2, "r.V.F").WithArguments("field", "V").WithLocation(7, 5));
}

[Theory, CombinatorialData, WorkItem("https://github.com/dotnet/roslyn/issues/73741")]
public void MutatingThroughRefFields_05(
[CombinatorialValues("ref", "")] string eRef,
[CombinatorialValues("readonly", "")] string vReadonly)
{
var source = $$"""
using System;
V[] arr = new V[3];
foreach (ref var r in new E(arr))
{
r.S.F++;
}
foreach (var v in arr) Console.Write(v.S.F);
{{eRef}} struct E(V[] arr)
{
int i;
public E GetEnumerator() => this;
public {{vReadonly}} ref V Current => ref arr[i - 1];
public bool MoveNext() => i++ < arr.Length;
}
struct V
{
public S S;
}
struct S
{
public int F;
}
""";
CompileAndVerify(source, targetFramework: TargetFramework.Net70,
verify: Verification.Skipped,
expectedOutput: ExecutionConditionUtil.IsDesktop ? null : "111").VerifyDiagnostics();
}

[Theory, CombinatorialData, WorkItem("https://github.com/dotnet/roslyn/issues/73741")]
public void MutatingThroughRefFields_06(
[CombinatorialValues("ref", "")] string eRef,
[CombinatorialValues("readonly", "")] string vReadonly,
[CombinatorialValues("readonly", "")] string vReadonlyInner)
{
var source = $$"""
using System;
V[] arr = new V[3];
foreach (ref readonly var r in new E(arr))
{
r.S.F++;
}
foreach (var v in arr) Console.Write(v.S.F);
{{eRef}} struct E(V[] arr)
{
int i;
public E GetEnumerator() => this;
public {{vReadonly}} ref {{vReadonlyInner}} V Current => ref arr[i - 1];
public bool MoveNext() => i++ < arr.Length;
}
struct V
{
public S S;
}
struct S
{
public int F;
}
""";
CreateCompilation(source, targetFramework: TargetFramework.Net70).VerifyDiagnostics(
// (7,5): error CS1654: Cannot modify members of 'r' because it is a 'foreach iteration variable'
// r.S.F++;
Diagnostic(ErrorCode.ERR_AssgReadonlyLocal2Cause, "r.S.F").WithArguments("r", "foreach iteration variable").WithLocation(7, 5));
}
}
}
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