(#72) Parser: typedef name usage & hacky hacks

.gitignore

@@ -7,4 +7,5 @@ obj/
 *.dll
 *.exe
 *.runtimeconfig.json
+*.received.txt
 *.user

Cesium.Ast/Declarations.cs

@@ -23,6 +23,8 @@ public record StructOrUnionSpecifier(
     string? Identifier,
     ImmutableArray<StructDeclaration> StructDeclarations) : ITypeSpecifier;
 
+public record NamedTypeSpecifier(string TypeDefName) : ITypeSpecifier;
+
 // 6.7.2.1 Structure and union specifiers
 public enum ComplexTypeKind
 {
@@ -61,8 +63,13 @@ public interface IDirectDeclarator
 {
     IDirectDeclarator? Base { get; }
 }
-public record IdentifierDirectDeclarator(string Identifier) : IDirectDeclarator
+public record IdentifierDirectDeclarator(string? Identifier) : IDirectDeclarator
 {
+    // HACK: This property is only mutable from CParser.TypeDefNameIdentifierHack.
+    // This requirement is caused by an issue https://github.com/LanguageDev/Yoakke/issues/138
+    // TODO: Eventually, we should get rid of that.
+    public string? Identifier { get; set; } = Identifier;
+
     public IDirectDeclarator? Base => null;
 }
 public record ArrayDirectDeclarator(

Cesium.CodeGen.Tests/CodeGenMethodTests.UninitializedVariable.verified.txt

@@ -0,0 +1,5 @@
+System.Int32 <Module>::main()
+  Locals:
+    System.Int32 V_0
+  IL_0000: ldc.i4 0
+  IL_0005: ret

Cesium.CodeGen.Tests/CodeGenMethodTests.cs

@@ -80,6 +80,8 @@ public void VarArgMainDoesNotCompile2() => DoesNotCompile(
 
     [Fact] public Task MultiDeclaration() => DoTest("int main() { int x = 0, y = 2 + 2; }");
 
+    [Fact] public Task UninitializedVariable() => DoTest("int main() { int x; return 0; }");
+
     [Fact]
     public Task Arithmetic() => DoTest(@"int main(void)
 {

Cesium.CodeGen.Tests/CodeGenTypeTests.cs

@@ -48,4 +48,8 @@ int bar(void)
 
     [Fact]
     public Task SingleFieldStructDefinition() => DoTest("typedef struct { int x; } foo;");
+
+    [Fact]
+    public Task TypeDefStructUsage() => DoTest(@"typedef struct { int x; } foo;
+int main(void) { foo x; return 0; }");
 }

Cesium.Parser.Tests/ParserTests/FullParserTests.cs

@@ -124,4 +124,8 @@ public Task PrefixIncrementTest() => DoTest(@"int main()
 
     [Fact]
     public Task DoubleTypeDef() => DoTest(@"typedef struct { int x; } foo, bar;");
+
+    [Fact]
+    public Task TypeDefStructUsage() => DoTest(@"typedef struct { int x; } foo;
+int main(void) { foo x; return 0; }");
 }

Cesium.Parser/CParser.cs

@@ -177,7 +177,19 @@ private static Expression MakeAssignmentExpression(
     private static Declaration MakeDeclaration(
         DeclarationSpecifiers specifiers,
         InitDeclaratorList? initDeclarators,
-        IToken _) => new(specifiers, initDeclarators);
+        IToken _)
+    {
+        var firstInitDeclarator = initDeclarators?.FirstOrDefault();
+        if (firstInitDeclarator != null)
+        {
+            var firstDeclarator = firstInitDeclarator.Declarator;
+            (specifiers, firstDeclarator) = TypeDefNameIdentifierHack(specifiers, firstDeclarator);
+            firstInitDeclarator = firstInitDeclarator with { Declarator = firstDeclarator };
+            initDeclarators = initDeclarators!.Value.RemoveAt(0).Insert(0, firstInitDeclarator);
+        }
+
+        return new(specifiers, initDeclarators);
+    }
 
     [Rule("declaration_specifiers: storage_class_specifier declaration_specifiers?")]
     [Rule("declaration_specifiers: type_specifier declaration_specifiers?")]
@@ -238,7 +250,10 @@ private static ITypeSpecifier MakeComplexTypeSpecifier(StructOrUnionSpecifier st
         structOrUnionSpecifier;
 
     // TODO: [Rule("type_specifier: enum_specifier")]
-    // TODO: [Rule("type_specifier: typedef_name")]
+
+    [Rule("type_specifier: typedef_name")]
+    private static ITypeSpecifier MakeNamedTypeSpecifier(IToken typeDefName) =>
+        new NamedTypeSpecifier(typeDefName.Text);
 
     // 6.7.2.1 Structure and union specifiers
 
@@ -315,9 +330,9 @@ private static StructDeclaratorList MakeStructDeclaratorList(
     private static Declarator MakeDeclarator(Pointer? pointer, IDirectDeclarator directDeclarator) =>
         new(pointer, directDeclarator);
 
-    [Rule("direct_declarator: Identifier")]
-    private static IDirectDeclarator MakeDirectDeclarator(ICToken identifier) =>
-        new IdentifierDirectDeclarator(identifier.Text);
+    [Rule("direct_declarator: Identifier?")]
+    private static IDirectDeclarator MakeDirectDeclarator(ICToken? identifier) =>
+        new IdentifierDirectDeclarator(identifier?.Text);
 
     // TODO: direct_declarator: ( declarator )
 
@@ -378,7 +393,11 @@ private static ParameterList MakeParameterList(ParameterList prev, ICToken _, Pa
     [Rule("parameter_declaration: declaration_specifiers declarator")]
     private static ParameterDeclaration MakeParameterTypeList(
         DeclarationSpecifiers specifiers,
-        Declarator declarator) => new(specifiers, declarator);
+        Declarator declarator)
+    {
+        (specifiers, declarator) = TypeDefNameIdentifierHack(specifiers, declarator);
+        return new(specifiers, declarator);
+    }
 
     [Rule("parameter_declaration: declaration_specifiers abstract_declarator?")]
     private static ParameterDeclaration MakeParameterTypeList(
@@ -442,7 +461,9 @@ private static IDirectAbstractDeclarator MakeDirectAbstractDeclarator(
     //     direct-abstract-declarator? [ * ]
     //     direct-abstract-declarator? ( parameter-type-list? )
 
-    // TODO: 6.7.8 Type definitions
+    // 6.7.8 Type definitions
+    [Rule("typedef_name: Identifier")]
+    private static IToken MakeTypeDefName(IToken identifier) => identifier;
 
     // 6.7.9 Initialization
 
@@ -533,7 +554,11 @@ private static FunctionDefinition MakeFunctionDefinition(
         DeclarationSpecifiers specifiers,
         Declarator declarator,
         ImmutableArray<Declaration>? declarationList,
-        CompoundStatement statement) => new(specifiers, declarator, declarationList, statement);
+        CompoundStatement statement)
+    {
+        (specifiers, declarator) = TypeDefNameIdentifierHack(specifiers, declarator);
+        return new(specifiers, declarator, declarationList, statement);
+    }
 
     [Rule("declaration_list: declaration")]
     private static ImmutableArray<Declaration> MakeDeclarationList(Declaration declaration) =>
@@ -608,4 +633,37 @@ private static ImmutableArray<Declaration> MakeDeclarationList(
     // TODO: 6.10.7 Null directive
     // TODO: 6.10.8 Predefined macro names
     // TODO: 6.10.9 Pragma operator
+
+    // HACK: The existence of this method is caused caused by an issue https://github.com/LanguageDev/Yoakke/issues/138
+    // As no simple workaround exist, we have to do ugly manipulations in parser and AST to support this.
+    // TODO: Eventually, I hope we'll get rid of that.
+    private static (DeclarationSpecifiers, Declarator) TypeDefNameIdentifierHack(
+        DeclarationSpecifiers specifiers,
+        Declarator declarator)
+    {
+        var directDeclarator = declarator.DirectDeclarator;
+        IdentifierDirectDeclarator? identifierDeclarator = null;
+        while (directDeclarator != null && identifierDeclarator == null)
+        {
+            identifierDeclarator = directDeclarator as IdentifierDirectDeclarator;
+            directDeclarator = directDeclarator.Base;
+        }
+
+        if (identifierDeclarator is { Identifier: null })
+        {
+            var lastSpecifier = specifiers.LastOrDefault();
+            if (lastSpecifier is NamedTypeSpecifier { TypeDefName: var tn })
+            {
+                specifiers = specifiers.RemoveAt(specifiers.Length - 1);
+                identifierDeclarator.Identifier = tn;
+            }
+        }
+
+        if (identifierDeclarator is { Identifier: null })
+            throw new NotSupportedException(
+                "THIS IS A BUG! It is caused by a hack in parsing for the sake of `typedef_name`." +
+                $" Please report to the Cesium maintainers: [{string.Join(",", specifiers)}] {declarator}.");
+
+        return (specifiers, declarator);
+    }
 }