feat: support .NET Standard 2.0

.github/scripts/check-package.py

@@ -8,7 +8,7 @@
 assert len(packages) == 1, packages
 with zipfile.ZipFile(packages[0]) as package:
     names = package.namelist()
-    assert "lib/net10.0/DimensionalQuantities.dll" in names
+    assert "lib/netstandard2.0/DimensionalQuantities.dll" in names
     assert "analyzers/dotnet/cs/DimensionalQuantities.Roslyn.dll" in names
     assert not any("Microsoft.CodeAnalysis" in name for name in names)
     specification = ET.fromstring(package.read("DimensionalQuantities.nuspec"))

README.md

@@ -13,7 +13,7 @@ A C# library for dimensional quantities, with generated type aliases, SI unit co
 
 ## Usage
 
-Requires .NET 10 and C# 14. The `DimensionalQuantities` NuGet package includes both the runtime library and its source generator.
+The runtime library targets .NET Standard 2.0. Consumers need a C# 14 compiler for the generated extension blocks. The `DimensionalQuantities` NuGet package includes both the runtime library and its source generator.
 
 ```csharp
 Voltage voltage = Voltage.FromVolts(12);

src/DimensionalQuantities.IntegrationTests/DimensionalQuantities.IntegrationTests.csproj

@@ -13,7 +13,7 @@
   <ItemGroup>
     <ProjectReference Include="../DimensionalQuantities/DimensionalQuantities.csproj" />
     <ProjectReference Include="../DimensionalQuantities.Roslyn/DimensionalQuantities.Roslyn.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
-    <Analyzer Include="../DimensionalQuantities/bin/$(Configuration)/net10.0/DimensionalQuantities.dll" />
+    <Analyzer Include="../DimensionalQuantities/bin/$(Configuration)/netstandard2.0/DimensionalQuantities.dll" />
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Microsoft.Build" Version="18.9.6" ExcludeAssets="runtime" PrivateAssets="all" />

src/DimensionalQuantities.IntegrationTests/GeneratedQuantityTests/PackagedGeneratorTests.cs

@@ -23,7 +23,7 @@ public void PackagedGeneratorConvertsVoltageInConsumer()
 	{
 		string sourceProject = Path.GetFullPath(Path.Combine(AppContext.BaseDirectory, "..", "..", "..", "..", "DimensionalQuantities", "DimensionalQuantities.csproj"));
 		FileInfo nupkg = PackLibrary(sourceProject, _scratch);
-		using PackageRepository repository = PackageRepository.Create(_scratch);
+		using PackageRepository repository = PackageRepository.Create(_scratch, new Uri("https://api.nuget.org/v3/index.json"));
 		repository.Package(nupkg, out Package package);
 
 		string consumerDirectory = Path.Combine(_scratch, "consumer");
@@ -39,9 +39,18 @@ public static double ConvertVoltage(double volts)
 					Voltage voltage = Voltage.FromVolts(volts);
 					return voltage.AsVolts();
 				}
+
+				public static double MultiplyVoltageCurrent(double volts, double amps)
+				{
+					Voltage voltage = Voltage.FromVolts(volts);
+					Current current = Current.FromAmps(amps);
+					Power power = voltage * current;
+					return power.AsWatts();
+				}
 			}
 			""");
-		ProjectCreator creator = ProjectCreator.Templates.SdkCsproj(path: consumerProject, targetFramework: "net10.0")
+		ProjectCreator creator = ProjectCreator.Templates.SdkCsproj(path: consumerProject, targetFramework: "netstandard2.0")
+			.Property("LangVersion", "14.0")
 			.ItemPackageReference(package)
 			.Save();
 
@@ -51,13 +60,16 @@ public static double ConvertVoltage(double volts)
 			Assert.True(built, $"Consumer build failed.{Environment.NewLine}{output.GetConsoleLog()}");
 		}
 
-		string assemblyFile = Path.Combine(consumerDirectory, "bin", "Debug", "net10.0", "Consumer.dll");
+		string assemblyFile = Path.Combine(consumerDirectory, "bin", "Debug", "netstandard2.0", "Consumer.dll");
 		Assembly assembly = Assembly.LoadFrom(assemblyFile);
 		Type consumerType = assembly.GetType("ConsumerProject.Consumer") ?? throw new InvalidOperationException("Consumer type was not built.");
 		MethodInfo convertVoltage = consumerType.GetMethod("ConvertVoltage") ?? throw new InvalidOperationException("Consumer Voltage conversion was not built.");
+		MethodInfo multiplyVoltageCurrent = consumerType.GetMethod("MultiplyVoltageCurrent") ?? throw new InvalidOperationException("Consumer arithmetic was not built.");
 		double result = Assert.IsType<double>(convertVoltage.Invoke(null, [12.5]));
-		double expected = 12.5;
-		Assert.Equal(expected, result);
+		double product = Assert.IsType<double>(multiplyVoltageCurrent.Invoke(null, [12.5, 2.0]));
+		Assert.Multiple(
+			() => Assert.Equal(12.5, result),
+			() => Assert.Equal(25.0, product));
 	}
 
 	public void Dispose()

src/DimensionalQuantities.Roslyn/DimensionalQuantities.Roslyn.csproj

@@ -1,13 +1,14 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>net10.0</TargetFramework>
+    <TargetFramework>netstandard2.0</TargetFramework>
     <IsRoslynComponent>true</IsRoslynComponent>
     <EnforceExtendedAnalyzerRules>true</EnforceExtendedAnalyzerRules>
     <IsPackable>false</IsPackable>
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="../DimensionalQuantities/DimensionalQuantities.csproj" PrivateAssets="all" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.9.0" PrivateAssets="all" />
+    <PackageReference Include="PolySharp" Version="1.15.0" PrivateAssets="all" />
   </ItemGroup>
   <ItemGroup>
     <InternalsVisibleTo Include="DimensionalQuantities.Roslyn.Tests" />

src/DimensionalQuantities.Roslyn/Generators/QuantitySourceEmitter.cs

@@ -55,7 +55,10 @@ private static IReadOnlyDictionary<string, Rational> CollectConversions(IReadOnl
 				throw new InvalidOperationException($"Unit {name} has conflicting SI scales.");
 			}
 
-			conversions.TryAdd(name, scaleExponent);
+			if (!conversions.ContainsKey(name))
+			{
+				conversions.Add(name, scaleExponent);
+			}
 		}
 
 		return conversions;
@@ -142,7 +145,7 @@ private static string RenderAccessor(string variableName, ConversionDefinition c
 		return $"public double {conversion.AccessorName}({parameters}) => {variableName}.AsArbitrarySiComponents(overallScaleExponent: {conversion.ScaleExponentExpression});";
 	}
 
-	private static string FormatExponent(Rational exponent) => double.CreateChecked(exponent).ToString("R", CultureInfo.InvariantCulture) + "d";
+	private static string FormatExponent(Rational exponent) => ((double)exponent).ToString("R", CultureInfo.InvariantCulture) + "d";
 
 	private static Type[] GetExponentTypes(Dimension dimension) =>
 	[