Initial C# code generator by pepone · Pull Request #4314 · icerpc/icerpc-csharp

pepone · 2026-03-17T20:47:32Z

ZeroC.Slice.Generator generates C# code for Slice types
IceRpc.Slice.Generator generates C# code for proxy/dispatch
ZeroC.Slice.Symbols C# model build from compiler definitions to use in C# code genertors.

The generator can be run with:

 ../slicec/target/debug/slicec tests/IceRpc.Slice.CodeGen.Tests/*.slice -R slice | dotnet run --project src/ZeroC.Slice.Generator/ZeroC.Slice.Generator.csproj

or

 ../slicec/target/debug/slicec tests/IceRpc.Slice.CodeGen.Tests/*.slice -R slice | dotnet run --project src/IceRpc.Slice.Generator/IceRpc.Slice.Generator.csproj

DocComment generation is not yet done, in part because slicec is not yet encoding comments.
ZeroC.Slice.Generator/GeneratorDriver.cs contains the boilerplate code to decode and encode the generator request and convert from the compiler symbols to the symbols used by the generators.

There are separate generators for enums, enum struct, struct. Removed the base Generator class that did too many things from previous PR, and split this into extension for IType, Field, ...

- ZeroC.Slice.Generator generates C# code from slicec encoded definitions - ZeroC.Slice.Symbols C# model build from compiler definitions to use in C# code genertors.

Copilot

Pull request overview

This PR introduces an initial Slice-to-C# code generation pipeline by adding a decoded-compiler model (ZeroC.Slice.Symbols) and a generator executable (ZeroC.Slice.Generator) that reads Slice2-encoded requests, validates C#-specific attributes, and emits generated C# code.

Changes:

Added ZeroC.Slice.Symbols to model compiler-decoded Slice definitions with resolved type references.
Added ZeroC.Slice.Generator executable to validate cs::* attributes and generate C# code for structs and enums.
Wired new projects into the solution and made small CodeBuilder pragma formatting adjustments.

Reviewed changes

Copilot reviewed 44 out of 46 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
src/ZeroC.Slice.Symbols/ZeroC.Slice.Symbols.csproj	New symbols/model project for decoded Slice compiler output.
src/ZeroC.Slice.Symbols/TypeRef.cs	Adds `TypeRef` model (type + attributes).
src/ZeroC.Slice.Symbols/TypeAlias.cs	Adds Slice type-alias symbol model.
src/ZeroC.Slice.Symbols/SymbolConverter.cs	Converts compiler DTOs into rich symbol graph with resolution/caching.
src/ZeroC.Slice.Symbols/Struct.cs	Adds Slice struct symbol model.
src/ZeroC.Slice.Symbols/SliceFile.cs	Adds Slice file container model.
src/ZeroC.Slice.Symbols/SequenceType.cs	Adds sequence type symbol model.
src/ZeroC.Slice.Symbols/ResultType.cs	Adds built-in result type model.
src/ZeroC.Slice.Symbols/Operation.cs	Adds interface operation model.
src/ZeroC.Slice.Symbols/Module.cs	Adds module model (identifier + attributes).
src/ZeroC.Slice.Symbols/Interface.cs	Adds interface symbol model.
src/ZeroC.Slice.Symbols/IType.cs	Adds marker interface for referencable types.
src/ZeroC.Slice.Symbols/ISymbol.cs	Adds marker interface for file-level symbols.
src/ZeroC.Slice.Symbols/Field.cs	Adds shared field model (struct fields/op params/enum fields).
src/ZeroC.Slice.Symbols/EnumWithUnderlying.cs	Adds enum-with-underlying models (typed enumerator values).
src/ZeroC.Slice.Symbols/EnumWithFields.cs	Adds enum-with-fields model for discriminated unions.
src/ZeroC.Slice.Symbols/Entity.cs	Adds shared base for named Slice entities (identifier/attributes/module).
src/ZeroC.Slice.Symbols/DictionaryType.cs	Adds dictionary type symbol model.
src/ZeroC.Slice.Symbols/CustomType.cs	Adds custom type symbol model.
src/ZeroC.Slice.Symbols/Compiler/SyntaxElements.cs	Adds auto-generated compiler DTOs for syntax elements.
src/ZeroC.Slice.Symbols/Compiler/DocComment.cs	Adds auto-generated compiler DTOs for doc comments.
src/ZeroC.Slice.Symbols/Compiler/CodeGenerator.cs	Adds auto-generated compiler DTOs for generator I/O messages.
src/ZeroC.Slice.Symbols/Builtin.cs	Adds builtin type kind enum and builtin type model.
src/ZeroC.Slice.Symbols/AttributeExtensions.cs	Adds attribute list query helpers on symbol attributes.
src/ZeroC.Slice.Symbols/Attribute.cs	Adds attribute value type (directive + args).
src/ZeroC.Slice.Generator/ZeroC.Slice.Generator.csproj	New generator executable project and dependencies.
src/ZeroC.Slice.Generator/TypeRefExtensions.cs	Adds C#-generation helpers for `TypeRef` (sizes, value-type checks, lambdas).
src/ZeroC.Slice.Generator/StructGenerator.cs	Generates C# record structs + encode/decode plumbing for Slice structs.
src/ZeroC.Slice.Generator/StringExtensions.cs	Adds identifier casing helpers (Pascal/camel).
src/ZeroC.Slice.Generator/Program.cs	Implements generator executable request decode + response encode.
src/ZeroC.Slice.Generator/ModuleExtensions.cs	Maps Slice modules to C# namespaces (supports `cs::namespace`).
src/ZeroC.Slice.Generator/ITypeExtensions.cs	Central C# mapping/encode/decode expressions for all `IType` shapes.
src/ZeroC.Slice.Generator/FieldExtensions.cs	Adds field ordering + encode/decode expression helpers.
src/ZeroC.Slice.Generator/EnumWithUnderlyingGenerator.cs	Generates C# enums + encoder/decoder extension classes.
src/ZeroC.Slice.Generator/EnumWithFieldsGenerator.cs	Generates Dunet unions for enums with fields + codec extensions.
src/ZeroC.Slice.Generator/EntityExtensions.cs	Adds naming/access modifier helpers based on `cs::*` attributes.
src/ZeroC.Slice.Generator/CodeBlockExtensions.cs	Writes `cs::attribute` as real C# attributes.
src/ZeroC.Slice.Generator/CSAttributeValidator.cs	Validates `cs::*` attribute usage and produces diagnostics.
src/ZeroC.Slice.Generator/CSAttribute.cs	Defines `cs::*` directive constants.
src/ZeroC.Slice.Generator/BuiltinExtensions.cs	Maps Slice builtins to C# types and codec suffixes.
src/ZeroC.Slice.Generator/BuilderExtensions.cs	Applies `cs::attribute` to CodeBuilder builders.
src/ZeroC.Slice.Generator/AttributeExtensions.cs	Generator-specific attribute filtering (`cs::attribute`).
src/ZeroC.CodeBuilder/CommentTag.cs	Adjusts pragma formatting in code generation comments.
src/ZeroC.CodeBuilder/CodeBlock.cs	Adjusts pragma formatting in indentation helper.
IceRpc.slnx	Adds the new generator + symbols projects to the solution.
.vscode/cspell.json	Adds a small spelling dictionary entry used by new code.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

You can also share your feedback on Copilot code review. Take the survey.

pepone · 2026-03-17T21:31:39Z

+            string moduleScope = file.ModuleDeclaration.Identifier;
+            foreach (Compiler.Symbol symbol in file.Contents)
+            {
+                if (GetNamedIdentifier(symbol) is string id)
+                {
+                    _named.TryAdd($"{moduleScope}::{id}", (file, symbol));
+                }


module is always not empty, we should remove the other check.

pepone · 2026-03-17T21:33:40Z

+                Enumerators = raw.Enumerators.Select(e => new EnumWithFields.Enumerator
+                {
+                    Identifier = e.EntityInfo.Identifier,
+                    Attributes = ConvertAttributes(e.EntityInfo.Attributes),
+                    Module = module,
+                    Discriminant = (int)e.Value.AbsoluteValue,
+                    Fields = e.Fields.Select(f => ConvertField(f, file, module)).ToImmutableList(),


Cast to int is fine here

The range of these discriminants is 0 to 2,147,483,647 (int32 max).

See https://docs.icerpc.dev/slice2/language-guide/enum-types

+                body.WriteLine($$"""
+                    bitSequenceWriter.Write({param} != null);
+                    if ({{param}} != null)
+                    {
+                        {{encodeExpr}};
+                    }
+                    """);


+            string decodeExpr = field.DecodeField(currentNamespace);
+            return $"bitSequenceReader.Read() ? {decodeExpr} : null";


+        e.Value.ToString(null, CultureInfo.InvariantCulture);
+
+    private static string GetArticle(string word) =>
+        word.Length > 0 && "aeiouAEIOU".Contains(word[0], StringComparison.Ordinal) ? "an" : "a";


+                string minValue = enumDef.Enumerators.Min(e => Convert.ToInt64(e.Value, CultureInfo.InvariantCulture))
+                    .ToString(CultureInfo.InvariantCulture);
+                string maxValue = enumDef.Enumerators.Max(e => Convert.ToInt64(e.Value, CultureInfo.InvariantCulture))
+                    .ToString(CultureInfo.InvariantCulture);


+        var values = enumDef.Enumerators.Select(e => Convert.ToInt64(e.Value, CultureInfo.InvariantCulture)).ToList();
+        long min = values.Min();
+        long max = values.Max();
+        return enumDef.Enumerators.Count < (max - min + 1);
+    }


+string op = decoder.DecodeString();
+
+// Decode source files and reference files.
+Compiler.SliceFile[] sourceFiles = decoder.DecodeSequence((ref decoder) => new Compiler.SliceFile(ref decoder));
+Compiler.SliceFile[] referenceFiles = decoder.DecodeSequence((ref decoder) => new Compiler.SliceFile(ref decoder));


bernardnormier

Looks good. Will re-review later.

bernardnormier · 2026-03-17T21:27:41Z

  "language": "en",
  "words": [
    "aarch",
+    "aeiou",


For some words like aeiou, it's better to disable cspell with

// cspell:disable-line

bernardnormier · 2026-03-17T21:38:55Z

+    public required ImmutableList<Attribute> Attributes { get; init; }
+
+    /// <summary>Gets the list of symbols defined in the Slice file.</summary>
+    public required ImmutableList<ISymbol> Contents { get; init; }


As I understand it, an ISymbol is either a type or an interface. So if we split this Contents in Types and Interfaces, we can eliminate ISymbol?

bernardnormier · 2026-03-17T21:41:33Z

+
+/// <summary>Base for all symbols that can appear in a <see cref="SliceFile"/>.</summary>
+#pragma warning disable CA1040 // Avoid empty interfaces
+public interface ISymbol;


I would prefer to avoid ISymbol as it's also Microsoft.CodeAnalysis.ISymbol.

…ze optimization - Constrain EnumWithUnderlying<T> to INumber<T> instead of just struct, enabling generic math (Min/Max, CreateChecked, arithmetic) without Convert.ToInt64 - Add full-range early return in NeedsHashSetValidation to prevent overflow for small types like sbyte - Add tagged collection size optimization for sequences with fixed-size elements (> 1 byte) and dictionaries with all-fixed-size key/value types

Copilot

Pull request overview

Adds an initial Slice-to-C# code generation pipeline by introducing a rich Slice symbol model (ZeroC.Slice.Symbols) plus two generator executables: a general Slice codec generator (ZeroC.Slice.Generator) and an IceRPC-specific generator for Slice interfaces (IceRpc.Slice.Generator).

Changes:

Introduce ZeroC.Slice.Symbols with a SymbolConverter that resolves compiler-decoded Slice definitions into a generator-friendly symbol graph.
Add ZeroC.Slice.Generator codegen entrypoint + generator pipeline (stdin/stdout protocol), and generators for structs and enums (with underlying / with fields).
Add IceRpc.Slice.Generator to generate proxy/dispatch code for Slice interfaces and include the new projects in the solution.

Reviewed changes

Copilot reviewed 51 out of 53 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/ZeroC.Slice.Symbols/ZeroC.Slice.Symbols.csproj	New symbols project for generator-facing model types.
src/ZeroC.Slice.Symbols/TypeRef.cs	Adds `TypeRef` model used throughout symbol graph.
src/ZeroC.Slice.Symbols/TypeAlias.cs	Adds symbol model for Slice type aliases.
src/ZeroC.Slice.Symbols/SymbolConverter.cs	Converts compiler-decoded symbols into rich symbols and resolves references.
src/ZeroC.Slice.Symbols/Struct.cs	Adds symbol model for Slice structs.
src/ZeroC.Slice.Symbols/SliceFile.cs	Adds model for a Slice file (path/module/contents).
src/ZeroC.Slice.Symbols/SequenceType.cs	Adds symbol model for Slice sequence types.
src/ZeroC.Slice.Symbols/ResultType.cs	Adds symbol model for Slice result type.
src/ZeroC.Slice.Symbols/Operation.cs	Adds symbol model for Slice operations.
src/ZeroC.Slice.Symbols/Module.cs	Adds symbol model for Slice modules.
src/ZeroC.Slice.Symbols/Interface.cs	Adds symbol model for Slice interfaces.
src/ZeroC.Slice.Symbols/IType.cs	Adds marker interface for referencable types.
src/ZeroC.Slice.Symbols/ISymbol.cs	Adds marker interface for file-level symbols.
src/ZeroC.Slice.Symbols/Field.cs	Adds symbol model for fields (struct/enum/op contexts).
src/ZeroC.Slice.Symbols/EnumWithUnderlying.cs	Adds enum model for enums with underlying integral type.
src/ZeroC.Slice.Symbols/EnumWithFields.cs	Adds enum model for enums with fields (union-like).
src/ZeroC.Slice.Symbols/Entity.cs	Adds base type for named Slice entities.
src/ZeroC.Slice.Symbols/DictionaryType.cs	Adds symbol model for Slice dictionary types.
src/ZeroC.Slice.Symbols/CustomType.cs	Adds model for user-mapped custom types.
src/ZeroC.Slice.Symbols/Compiler/SyntaxElements.cs	Adds generated compiler AST model types (auto-generated).
src/ZeroC.Slice.Symbols/Compiler/DocComment.cs	Adds generated doc-comment model types (auto-generated).
src/ZeroC.Slice.Symbols/Compiler/CodeGenerator.cs	Adds generated codegen protocol model types (auto-generated).
src/ZeroC.Slice.Symbols/Builtin.cs	Adds builtin kind enumeration + builtin type symbol.
src/ZeroC.Slice.Symbols/AttributeExtensions.cs	Adds helpers for querying Slice attributes.
src/ZeroC.Slice.Symbols/Attribute.cs	Adds attribute model (directive + args).
src/ZeroC.Slice.Generator/ZeroC.Slice.Generator.csproj	New executable project for Slice codec code generation.
src/ZeroC.Slice.Generator/TypeRefExtensions.cs	Adds C# mapping helpers for `TypeRef` in generated code.
src/ZeroC.Slice.Generator/StructGenerator.cs	Generates C# record structs + encode/decode members for Slice structs.
src/ZeroC.Slice.Generator/StringExtensions.cs	Adds identifier casing helpers for generated C# names.
src/ZeroC.Slice.Generator/Program.cs	Generator entrypoint wiring symbol-to-code generation.
src/ZeroC.Slice.Generator/ModuleExtensions.cs	Adds module-to-namespace mapping logic.
src/ZeroC.Slice.Generator/ITypeExtensions.cs	Core encode/decode/type-string generation logic per Slice type.
src/ZeroC.Slice.Generator/GeneratorDriver.cs	Implements stdin/stdout protocol + orchestration for generation.
src/ZeroC.Slice.Generator/FieldExtensions.cs	Shared field encode/decode helpers used by multiple generators.
src/ZeroC.Slice.Generator/EnumWithUnderlyingGenerator.cs	Generates C# enums + encoder/decoder extensions.
src/ZeroC.Slice.Generator/EnumWithFieldsGenerator.cs	Generates Dunet unions + encoder/decoder extensions for enums-with-fields.
src/ZeroC.Slice.Generator/EntityExtensions.cs	Adds naming/access/extension-class helpers for symbol entities.
src/ZeroC.Slice.Generator/CodeBlockExtensions.cs	Adds helpers to emit attributes into generated code blocks.
src/ZeroC.Slice.Generator/CSAttributeValidator.cs	Validates cs::* attribute usage and reports diagnostics.
src/ZeroC.Slice.Generator/CSAttribute.cs	Declares constants for cs::* attribute directives.
src/ZeroC.Slice.Generator/BuiltinExtensions.cs	Adds C# type and codec suffix mapping for builtins.
src/ZeroC.Slice.Generator/BuilderExtensions.cs	Adds helper to attach cs::attribute attributes to builders.
src/ZeroC.Slice.Generator/AttributeExtensions.cs	Adds generator-specific attribute filtering helpers.
src/ZeroC.CodeBuilder/ContainerBuilder.cs	Minor typing adjustments in loops for comments/attributes.
src/ZeroC.CodeBuilder/CommentTag.cs	Moves pragmas; affects formatting/warning scope.
src/ZeroC.CodeBuilder/CodeBlock.cs	Moves pragmas; affects formatting/warning scope.
src/IceRpc.Slice.Generator/ProxyGenerator.cs	Generates client interface + proxy struct + request/response helpers.
src/IceRpc.Slice.Generator/Program.cs	Generator entrypoint for IceRPC Slice interface/operations output.
src/IceRpc.Slice.Generator/OperationHelpers.cs	Shared helpers for operation signatures and payload encode/decode.
src/IceRpc.Slice.Generator/OperationExtensions.cs	Adds operation/interface helpers for streamed args/returns and bases.
src/IceRpc.Slice.Generator/IceRpc.Slice.Generator.csproj	New executable project for IceRPC-specific Slice generation.
src/IceRpc.Slice.Generator/DispatchGenerator.cs	Generates server-side service interface + request/response helpers.
IceRpc.slnx	Adds new generator and symbols projects to the solution.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

You can also share your feedback on Copilot code review. Take the survey.

pepone · 2026-03-19T15:45:10Z

+        var defaultCtor = new FunctionBuilder("public", "", proxyName, FunctionType.BlockBody);
+        defaultCtor.AddComment(
+            "summary",
+            @"Constructs a proxy with an icerpc service address with path <see cref=""DefaultServicePath"" />.");


The empty body is correct, this is as per slicec-cs impl:

/// <summary>Constructs a proxy with an icerpc service address with path <see cref="DefaultServicePath" />.</summary> public MoreDerivedProxy() { }

+
+        if (includeTagEndMarker)
+        {
+            body.WriteLine($"{encoderName}.EncodeVarInt32(Slice2Definitions.TagEndMarker);");


+        parts.Count switch
+        {
+            0 => taskType,
+            1 => $"{taskType}<{parts[0].Split(' ')[0]}>",


bernardnormier · 2026-03-19T16:12:54Z

+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <!--Because an application's API isn't typically referenced from outside the assembly, types can be made internal -->
+    <NoWarn>CA1515</NoWarn>


https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca1515

Meaning we have public types that can/should be internal. Why disable this warning?

I got this when including the code builder

eroC.Slice.Generator net10.0 failed with 11 error(s) (0,2s) CSC : error CA1515: Because an application's API isn't typically referenced from outside the assembly, types can be made internal (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1515) /Users/jose/Documents/IceRPC/icerpc-csharp/src/ZeroC.CodeBuilder/CodeBlock.cs(8,21): error CA1515: Because an application's API isn't typically referenced from outside the assembly, types can be made internal (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1515) /Users/jose/Documents/IceRPC/icerpc-csharp/src/ZeroC.CodeBuilder/CommentTag.cs(8,21): error CA1515: Because an application's API isn't typically referenced from outside the assembly, types can be made internal (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1515)

bernardnormier · 2026-03-19T16:15:06Z

+
+namespace ZeroC.Slice.Generator;
+
+/// <summary>Helper methods for generating operation encode/decode code blocks.</summary>


A more typical C#-way to write helpers is to add extension method, such as OperationExtensions.

bernardnormier · 2026-03-19T16:17:32Z

+    }
+
+    /// <summary>Builds the EncodeStreamOf{Op} method for a streamed field (parameter or return value).</summary>
+    internal static CodeBlock BuildEncodeStreamMethod(Operation op, Field streamParam, string currentNamespace)


I am surprised you don't get a build warning for defining an internal method after a private one.

moved to op extensions

bernardnormier · 2026-03-19T16:18:10Z

+        string opName = op.Name;
+        string streamType = OperationExtensions.GetStreamTypeString(streamParam, currentNamespace);
+
+        var fn = new FunctionBuilder(


I would prefer "builder" or "functionBuilder" over "fn"

Initial C# code generator

a555ba7

- ZeroC.Slice.Generator generates C# code from slicec encoded definitions - ZeroC.Slice.Symbols C# model build from compiler definitions to use in C# code genertors.

pepone requested review from InsertCreativityHere, bernardnormier, Copilot and externl March 17, 2026 20:47

Copilot started reviewing on behalf of pepone March 17, 2026 20:48 View session

Copilot AI reviewed Mar 17, 2026

View reviewed changes

bernardnormier reviewed Mar 17, 2026

View reviewed changes

pepone added 7 commits March 18, 2026 15:27

Review fixes

a72eef3

Spell fixes

7ad005c

Merge remote-tracking branch 'origin/main' into zeroc-slice-generator

108f85c

Update generated code, and build fixes

e089bda

minor fix

8a3d7aa

Add RPC generator

c97ba2f

pepone requested review from bernardnormier and Copilot March 19, 2026 14:49

Copilot AI reviewed Mar 19, 2026

View reviewed changes

pepone added 2 commits March 19, 2026 16:47

Review fixes

0f94554

Merge remote-tracking branch 'origin/main' into zeroc-slice-generator

9d32eb2

bernardnormier approved these changes Mar 19, 2026

View reviewed changes

pepone added 9 commits March 19, 2026 17:25

Review fixes

2eeb0fd

Add LinkBase for ZeroC.CodeBuilder

83bbcb0

Review fixes

d277c01

Merge remote-tracking branch 'origin/main' into zeroc-slice-generator

be24bf4

Review fixes

bd8a452

Review fixes

e1e3cab

Review fixes

0d55c94

Merge remote-tracking branch 'origin/main' into zeroc-slice-generator

528343f

Merge remote-tracking branch 'origin/main' into zeroc-slice-generator

59e3f90

pepone merged commit 7555ccc into icerpc:main Mar 20, 2026
12 checks passed

		string decodeExpr = field.DecodeField(currentNamespace);
		return $"bitSequenceReader.Read() ? {decodeExpr} : null";


		namespace ZeroC.Slice.Generator;

		/// <summary>Helper methods for generating operation encode/decode code blocks.</summary>

Conversation

pepone commented Mar 17, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

bernardnormier left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

pepone commented Mar 17, 2026 •

edited

Loading