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Only prefer interpolated string handler conversions in C# 10 #55380

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Aug 3, 2021
Merged

Only prefer interpolated string handler conversions in C# 10 #55380

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498dce7
Only prefer interpolated string handler conversions in C# 10
333fred Aug 3, 2021
a673481
Correct test baseline in one leg.
333fred Aug 3, 2021
3e4dbde
Clarify comment.
333fred Aug 3, 2021
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11 changes: 9 additions & 2 deletions src/Compilers/CSharp/Portable/Binder/Semantics/OverloadResolution/OverloadResolution.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2429,8 +2429,15 @@ private BetterResult BetterConversionFromExpression(BoundExpression node, TypeSy
// and an implicit conversion C2 that converts from an expression E to a type T2,
// C1 is a better conversion than C2 if E is a non-constant interpolated string expression, C1
// is an interpolated string handler conversion, and C2 is not an interpolated string
// handler conversion
if (node is BoundUnconvertedInterpolatedString { ConstantValueOpt: null } or BoundBinaryOperator { IsUnconvertedInterpolatedStringAddition: true, ConstantValue: null })
// handler conversion.
// We deviate from our usual policy around language version not changing binding behavior here
// because this will cause existing code that chooses one overload to instead choose an overload
// that will immediately cause an error. True, the user does need to update their target framework
// or a library to a version that takes advantage of the feature, but we made this pragmatic
// choice after we received customer reports of problems in the space.
// https://github.com/dotnet/roslyn/issues/55345
if (_binder.Compilation.IsFeatureEnabled(MessageID.IDS_FeatureImprovedInterpolatedStrings) &&
node is BoundUnconvertedInterpolatedString { ConstantValueOpt: null } or BoundBinaryOperator { IsUnconvertedInterpolatedStringAddition: true, ConstantValue: null })
{
switch ((conv1.Kind, conv2.Kind))
{
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82 changes: 58 additions & 24 deletions src/Compilers/CSharp/Test/Semantic/Semantics/InterpolationTests.cs
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Expand Up @@ -4158,12 +4158,13 @@ .maxstack 5
");
}

[Theory]
[Theory, WorkItem(55345, "https://github.com/dotnet/roslyn/issues/55345")]
[InlineData(@"$""{1,2:f}Literal""")]
[InlineData(@"$""{1,2:f}"" + $""Literal""")]
public void HandlerConversionPreferredOverStringForNonConstant(string expression)
{
var code = @"
CultureInfoNormalizer.Normalize();
C.M(" + expression + @");
class C
{
Expand All @@ -4173,12 +4174,12 @@ public static void M(CustomHandler b)
}
public static void M(string s)
{
throw null;
System.Console.WriteLine(s);
}
}
";

var comp = CreateCompilation(new[] { code, GetInterpolatedStringCustomHandlerType("CustomHandler", "class", useBoolReturns: true) });
var comp = CreateCompilation(new[] { code, GetInterpolatedStringCustomHandlerType("CustomHandler", "class", useBoolReturns: true) }, parseOptions: TestOptions.Regular10);
VerifyInterpolatedStringExpression(comp);
var verifier = CompileAndVerify(comp, expectedOutput: @"
value:1
Expand All @@ -4188,29 +4189,62 @@ public static void M(string s)

verifier.VerifyIL(@"<top-level-statements-entry-point>", @"
{
// Code size 50 (0x32)
// Code size 55 (0x37)
.maxstack 4
.locals init (CustomHandler V_0)
IL_0000: ldc.i4.7
IL_0001: ldc.i4.1
IL_0002: newobj ""CustomHandler..ctor(int, int)""
IL_0007: stloc.0
IL_0008: ldloc.0
IL_0009: ldc.i4.1
IL_000a: box ""int""
IL_000f: ldc.i4.2
IL_0010: ldstr ""f""
IL_0015: callvirt ""bool CustomHandler.AppendFormatted(object, int, string)""
IL_001a: brfalse.s IL_0029
IL_001c: ldloc.0
IL_001d: ldstr ""Literal""
IL_0022: callvirt ""bool CustomHandler.AppendLiteral(string)""
IL_0027: br.s IL_002a
IL_0029: ldc.i4.0
IL_002a: pop
IL_002b: ldloc.0
IL_002c: call ""void C.M(CustomHandler)""
IL_0031: ret
IL_0000: call ""void CultureInfoNormalizer.Normalize()""
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Only change in the IL here is this line. Otherwise, C# 10 remains the same.

IL_0005: ldc.i4.7
IL_0006: ldc.i4.1
IL_0007: newobj ""CustomHandler..ctor(int, int)""
IL_000c: stloc.0
IL_000d: ldloc.0
IL_000e: ldc.i4.1
IL_000f: box ""int""
IL_0014: ldc.i4.2
IL_0015: ldstr ""f""
IL_001a: callvirt ""bool CustomHandler.AppendFormatted(object, int, string)""
IL_001f: brfalse.s IL_002e
IL_0021: ldloc.0
IL_0022: ldstr ""Literal""
IL_0027: callvirt ""bool CustomHandler.AppendLiteral(string)""
IL_002c: br.s IL_002f
IL_002e: ldc.i4.0
IL_002f: pop
IL_0030: ldloc.0
IL_0031: call ""void C.M(CustomHandler)""
IL_0036: ret
}
");

comp = CreateCompilation(new[] { code, GetInterpolatedStringCustomHandlerType("CustomHandler", "class", useBoolReturns: true) }, parseOptions: TestOptions.Regular9);
verifier = CompileAndVerify(comp, expectedOutput: @"1.00Literal");

verifier.VerifyIL(@"<top-level-statements-entry-point>", expression.Contains('+') ? @"
{
// Code size 37 (0x25)
.maxstack 2
IL_0000: call ""void CultureInfoNormalizer.Normalize()""
IL_0005: ldstr ""{0,2:f}""
IL_000a: ldc.i4.1
IL_000b: box ""int""
IL_0010: call ""string string.Format(string, object)""
IL_0015: ldstr ""Literal""
IL_001a: call ""string string.Concat(string, string)""
IL_001f: call ""void C.M(string)""
IL_0024: ret
}
"
: @"
{
// Code size 27 (0x1b)
.maxstack 2
IL_0000: call ""void CultureInfoNormalizer.Normalize()""
IL_0005: ldstr ""{0,2:f}Literal""
IL_000a: ldc.i4.1
IL_000b: box ""int""
IL_0010: call ""string string.Format(string, object)""
IL_0015: call ""void C.M(string)""
IL_001a: ret
}
");
}
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