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Handle passing a function pointer ref through a ref returning method (#…
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…49526)
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@333fred
333fred authored Dec 7, 2020
1 parent 1afc0cf commit 4faa3b3
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23 changes: 23 additions & 0 deletions src/Compilers/CSharp/Portable/Binder/Binder.ValueChecks.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2292,6 +2292,29 @@ internal static bool CheckRefEscape(SyntaxNode node, BoundExpression expr, uint
diagnostics,
isRefEscape: true);

case BoundKind.FunctionPointerInvocation:
var functionPointerInvocation = (BoundFunctionPointerInvocation)expr;

FunctionPointerMethodSymbol signature = functionPointerInvocation.FunctionPointer.Signature;
if (signature.RefKind == RefKind.None)
{
break;
}

return CheckInvocationEscape(
functionPointerInvocation.Syntax,
signature,
functionPointerInvocation.InvokedExpression,
signature.Parameters,
functionPointerInvocation.Arguments,
functionPointerInvocation.ArgumentRefKindsOpt,
argsToParamsOpt: default,
checkingReceiver,
escapeFrom,
escapeTo,
diagnostics,
isRefEscape: true);

case BoundKind.PropertyAccess:
var propertyAccess = (BoundPropertyAccess)expr;
var propertySymbol = propertyAccess.PropertySymbol;
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322 changes: 322 additions & 0 deletions src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenFunctionPointersTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -10677,6 +10677,328 @@ .locals init (int V_0, //i1
");
}

[Fact, WorkItem(49315, "https://github.com/dotnet/roslyn/issues/49315")]
public void ReturnByRefFromRefReturningMethod()
{
var verifier = CompileAndVerifyFunctionPointers(@"
unsafe
{
int i = 1;
ref int iRef = ref ReturnPtrByRef(&ReturnByRef, ref i);
iRef = 2;
System.Console.WriteLine(i);
static ref int ReturnPtrByRef(delegate*<ref int, ref int> ptr, ref int i)
=> ref ptr(ref i);
static ref int ReturnByRef(ref int i) => ref i;
}", expectedOutput: "2");

verifier.VerifyIL("<Program>$.<<Main>$>g__ReturnPtrByRef|0_0(delegate*<ref int, int>, ref int)", @"
{
// Code size 10 (0xa)
.maxstack 2
.locals init (delegate*<ref int, ref int> V_0)
IL_0000: ldarg.0
IL_0001: stloc.0
IL_0002: ldarg.1
IL_0003: ldloc.0
IL_0004: calli ""delegate*<ref int, ref int>""
IL_0009: ret
}
");
}

[Fact, WorkItem(49315, "https://github.com/dotnet/roslyn/issues/49315")]
public void ReturnByRefFromRefReturningMethod_FunctionPointerDoesNotReturnByRefError()
{
var comp = CreateCompilationWithFunctionPointers(@"
unsafe
{
int i = 1;
ref int iRef = ref ReturnPtrByRef(&ReturnByRef, ref i);
static ref int ReturnPtrByRef(delegate*<ref int, int> ptr, ref int i)
=> ref ptr(ref i);
static int ReturnByRef(ref int i) => i;
}", options: TestOptions.UnsafeReleaseExe);

comp.VerifyDiagnostics(
// (8,16): error CS8156: An expression cannot be used in this context because it may not be passed or returned by reference
// => ref ptr(ref i);
Diagnostic(ErrorCode.ERR_RefReturnLvalueExpected, "ptr(ref i)").WithLocation(8, 16)
);
}

[Fact, WorkItem(49315, "https://github.com/dotnet/roslyn/issues/49315")]
public void ReturnByRefFromRefReturningMethod_NotSafeToEscape()
{
var comp = CreateCompilationWithSpan(@"
using System;
unsafe
{
ref Span<int> spanRef = ref ReturnPtrByRef(&ReturnByRef);
static ref Span<int> ReturnPtrByRef(delegate*<ref Span<int>, ref Span<int>> ptr)
{
Span<int> span = stackalloc int[1];
return ref ptr(ref span);
}
static ref Span<int> ReturnByRef(ref Span<int> i) => ref i;
}", options: TestOptions.UnsafeReleaseExe);

comp.VerifyDiagnostics(
// (10,20): error CS8347: Cannot use a result of 'delegate*<ref Span<int>, Span<int>>' in this context because it may expose variables referenced by parameter '' outside of their declaration scope
// return ref ptr(ref span);
Diagnostic(ErrorCode.ERR_EscapeCall, "ptr(ref span)").WithArguments("delegate*<ref System.Span<int>, System.Span<int>>", "").WithLocation(10, 20),
// (10,28): error CS8168: Cannot return local 'span' by reference because it is not a ref local
// return ref ptr(ref span);
Diagnostic(ErrorCode.ERR_RefReturnLocal, "span").WithArguments("span").WithLocation(10, 28)
);
}

[Fact, WorkItem(49315, "https://github.com/dotnet/roslyn/issues/49315")]
public void ReturnByRefFromRefReturningMethod_SafeToEscape()
{
var comp = CreateCompilationWithSpan(@"
using System;
unsafe
{
Span<int> s = stackalloc int[1];
s[0] = 1;
ref Span<int> sRef = ref ReturnPtrByRef(&ReturnByRef, ref s);
sRef[0] = 2;
Console.WriteLine(s[0]);
static ref Span<int> ReturnPtrByRef(delegate*<ref Span<int>, ref Span<int>> ptr, ref Span<int> s)
=> ref ptr(ref s);
static ref Span<int> ReturnByRef(ref Span<int> i) => ref i;
}", options: TestOptions.UnsafeReleaseExe);

var verifier = CompileAndVerify(comp, expectedOutput: "2", verify: Verification.Skipped);

verifier.VerifyIL("<Program>$.<<Main>$>g__ReturnPtrByRef|0_0(delegate*<ref System.Span<int>, System.Span<int>>, ref System.Span<int>)", @"
{
// Code size 10 (0xa)
.maxstack 2
.locals init (delegate*<ref System.Span<int>, ref System.Span<int>> V_0)
IL_0000: ldarg.0
IL_0001: stloc.0
IL_0002: ldarg.1
IL_0003: ldloc.0
IL_0004: calli ""delegate*<ref System.Span<int>, ref System.Span<int>>""
IL_0009: ret
}
");
}

[Fact, WorkItem(49315, "https://github.com/dotnet/roslyn/issues/49315")]
public void ReturnByRefFromRefReturningMethod_RefReadonlyToRefError()
{
var comp = CreateCompilationWithFunctionPointers(@"
unsafe
{
int i = 1;
ref int iRef = ref ReturnPtrByRef(&ReturnByRef, ref i);
static ref int ReturnPtrByRef(delegate*<ref int, ref readonly int> ptr, ref int i)
=> ref ptr(ref i);
static ref readonly int ReturnByRef(ref int i) => ref i;
}", options: TestOptions.UnsafeReleaseExe);

comp.VerifyDiagnostics(
// (8,16): error CS8333: Cannot return method 'delegate*<ref int, int>' by writable reference because it is a readonly variable
// => ref ptr(ref i);
Diagnostic(ErrorCode.ERR_RefReturnReadonlyNotField, "ptr(ref i)").WithArguments("method", "delegate*<ref int, int>").WithLocation(8, 16)
);
}

[Fact, WorkItem(49315, "https://github.com/dotnet/roslyn/issues/49315")]
public void ReturnByRefFromRefReturningMethod_RefToRefReadonly()
{
var verifier = CompileAndVerifyFunctionPointers(@"
unsafe
{
int i = 1;
ref readonly int iRef = ref ReturnPtrByRef(&ReturnByRef, ref i);
i = 2;
System.Console.WriteLine(iRef);
static ref readonly int ReturnPtrByRef(delegate*<ref int, ref int> ptr, ref int i)
=> ref ptr(ref i);
static ref int ReturnByRef(ref int i) => ref i;
}", expectedOutput: "2");

verifier.VerifyIL("<Program>$.<<Main>$>g__ReturnPtrByRef|0_0(delegate*<ref int, int>, ref int)", @"
{
// Code size 10 (0xa)
.maxstack 2
.locals init (delegate*<ref int, ref int> V_0)
IL_0000: ldarg.0
IL_0001: stloc.0
IL_0002: ldarg.1
IL_0003: ldloc.0
IL_0004: calli ""delegate*<ref int, ref int>""
IL_0009: ret
}
");
}

[Fact, WorkItem(49315, "https://github.com/dotnet/roslyn/issues/49315")]
public void RefAssignment()
{
var verifier = CompileAndVerifyFunctionPointers(@"
unsafe
{
int i = 1;
delegate*<ref int, ref int> ptr = &ReturnByRef;
ref readonly int iRef = ref ptr(ref i);
i = 2;
System.Console.WriteLine(iRef);
static ref int ReturnByRef(ref int i) => ref i;
}", expectedOutput: "2");

verifier.VerifyIL("<top-level-statements-entry-point>", @"
{
// Code size 26 (0x1a)
.maxstack 2
.locals init (int V_0, //i
delegate*<ref int, ref int> V_1)
IL_0000: ldc.i4.1
IL_0001: stloc.0
IL_0002: ldftn ""ref int <Program>$.<<Main>$>g__ReturnByRef|0_0(ref int)""
IL_0008: stloc.1
IL_0009: ldloca.s V_0
IL_000b: ldloc.1
IL_000c: calli ""delegate*<ref int, ref int>""
IL_0011: ldc.i4.2
IL_0012: stloc.0
IL_0013: ldind.i4
IL_0014: call ""void System.Console.WriteLine(int)""
IL_0019: ret
}
");
}

[Fact, WorkItem(49315, "https://github.com/dotnet/roslyn/issues/49315")]
public void RefAssignmentThroughTernary()
{
var verifier = CompileAndVerifyFunctionPointers(@"
unsafe
{
int i = 1;
int i2 = 3;
delegate*<ref int, ref int> ptr = &ReturnByRef;
ref readonly int iRef = ref false ? ref i2 : ref ptr(ref i);
i = 2;
System.Console.WriteLine(iRef);
static ref int ReturnByRef(ref int i) => ref i;
}", expectedOutput: "2");

verifier.VerifyIL("<top-level-statements-entry-point>", @"
{
// Code size 26 (0x1a)
.maxstack 2
.locals init (int V_0, //i
delegate*<ref int, ref int> V_1)
IL_0000: ldc.i4.1
IL_0001: stloc.0
IL_0002: ldftn ""ref int <Program>$.<<Main>$>g__ReturnByRef|0_0(ref int)""
IL_0008: stloc.1
IL_0009: ldloca.s V_0
IL_000b: ldloc.1
IL_000c: calli ""delegate*<ref int, ref int>""
IL_0011: ldc.i4.2
IL_0012: stloc.0
IL_0013: ldind.i4
IL_0014: call ""void System.Console.WriteLine(int)""
IL_0019: ret
}
");
}

[Fact, WorkItem(49315, "https://github.com/dotnet/roslyn/issues/49315")]
public void RefReturnThroughTernary()
{
var verifier = CompileAndVerifyFunctionPointers(@"
unsafe
{
int i = 1;
int i2 = 3;
ref int iRef = ref ReturnPtrByRef(&ReturnByRef, ref i, ref i2);
iRef = 2;
System.Console.WriteLine(i);
static ref int ReturnPtrByRef(delegate*<ref int, ref int> ptr, ref int i, ref int i2)
=> ref false ? ref i2 : ref ptr(ref i);
static ref int ReturnByRef(ref int i) => ref i;
}", expectedOutput: "2");

verifier.VerifyIL("<Program>$.<<Main>$>g__ReturnPtrByRef|0_0(delegate*<ref int, int>, ref int, ref int)", @"
{
// Code size 10 (0xa)
.maxstack 2
.locals init (delegate*<ref int, ref int> V_0)
IL_0000: ldarg.0
IL_0001: stloc.0
IL_0002: ldarg.1
IL_0003: ldloc.0
IL_0004: calli ""delegate*<ref int, ref int>""
IL_0009: ret
}
");
}

[Fact, WorkItem(49315, "https://github.com/dotnet/roslyn/issues/49315")]
public void PassedAsByRefParameter()
{
var verifier = CompileAndVerifyFunctionPointers(@"
unsafe
{
int i = 1;
delegate*<ref int, ref int> ptr = &ReturnByRef;
ref readonly int iRef = ref ptr(ref ptr(ref i));
i = 2;
System.Console.WriteLine(iRef);
static ref int ReturnByRef(ref int i) => ref i;
}", expectedOutput: "2");

verifier.VerifyIL("<top-level-statements-entry-point>", @"
{
// Code size 34 (0x22)
.maxstack 2
.locals init (int V_0, //i
delegate*<ref int, ref int> V_1,
delegate*<ref int, ref int> V_2)
IL_0000: ldc.i4.1
IL_0001: stloc.0
IL_0002: ldftn ""ref int <Program>$.<<Main>$>g__ReturnByRef|0_0(ref int)""
IL_0008: dup
IL_0009: stloc.1
IL_000a: stloc.2
IL_000b: ldloca.s V_0
IL_000d: ldloc.2
IL_000e: calli ""delegate*<ref int, ref int>""
IL_0013: ldloc.1
IL_0014: calli ""delegate*<ref int, ref int>""
IL_0019: ldc.i4.2
IL_001a: stloc.0
IL_001b: ldind.i4
IL_001c: call ""void System.Console.WriteLine(int)""
IL_0021: ret
}
");
}

private static readonly Guid s_guid = new Guid("97F4DBD4-F6D1-4FAD-91B3-1001F92068E5");
private static readonly BlobContentId s_contentId = new BlobContentId(s_guid, 0x04030201);

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