From 6752ace624c60ca0ee4a251d1001766acad9b4cb Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Tue, 30 Jun 2026 20:56:33 +0100
Subject: Support Rust type paths with generic args

---
 .../compiler/output/lang/rust/RustWriter.java      | 10 +++++++++
 .../output/lang/rust/ast/RustTypePath.java         | 26 ++++++++++++++++++----
 .../output/lang/rust/ast/RustTypePathSegment.java  | 26 +++++++++++++++++-----
 3 files changed, 52 insertions(+), 10 deletions(-)

(limited to 'src/main/java')

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriter.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriter.java
index 9153d83..6cd67c6 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriter.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriter.java
@@ -110,6 +110,16 @@ public class RustWriter implements AutoCloseable {
 
     private void writeTypePathSegment(RustTypePathSegment segment) throws IOException {
         writePathIdentSegment(segment.pathIdentSegment());
+
+        if (segment.args().isPresent()) {
+            this.writer.write("<");
+            writeWithSeparator(
+                segment.args().get(),
+                this::writeType,
+                () -> this.writer.write(", ")
+            );
+            this.writer.write(">");
+        }
     }
 
     private void writePathIdentSegment(RustPathIdentSegment pathIdentSegment) throws IOException {
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustTypePath.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustTypePath.java
index c55b53d..9b44334 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustTypePath.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustTypePath.java
@@ -3,8 +3,10 @@
 package org.zwobble.hobgoblin.compiler.output.lang.rust.ast;
 
 // Custom area start: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePath imports
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Optional;
 // Custom area end: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePath imports
 
 public record RustTypePath(java.util.List<org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment> segments) implements org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustType {
@@ -28,22 +30,38 @@ public record RustTypePath(java.util.List<org.zwobble.hobgoblin.compiler.output.
     // Custom area start: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePath body
     public static RustTypePath primitive(String name) {
         return new RustTypePath(List.of(
-            new RustTypePathSegment(new RustPathIdentSegmentIdentifier(new RustIdentifier(name)))
+            new RustTypePathSegment(
+                new RustPathIdentSegmentIdentifier(new RustIdentifier(name)),
+                Optional.empty()
+            )
         ));
     }
 
-    public static RustType of(String... names) {
+    public static RustTypePath of(String... names) {
         var segments = Arrays.stream(names)
-            .map(name -> new RustTypePathSegment(new RustPathIdentSegmentIdentifier(new RustIdentifier(name))))
+            .map(name -> new RustTypePathSegment(
+                new RustPathIdentSegmentIdentifier(new RustIdentifier(name)),
+                Optional.empty()
+            ))
             .toList();
         return new RustTypePath(segments);
     }
 
     public static RustType of(RustIdentifier... names) {
         var segments = Arrays.stream(names)
-            .map(name -> new RustTypePathSegment(new RustPathIdentSegmentIdentifier(name)))
+            .map(name -> new RustTypePathSegment(
+                new RustPathIdentSegmentIdentifier(name),
+                Optional.empty()
+            ))
             .toList();
         return new RustTypePath(segments);
     }
+
+    public RustType withArgs(List<RustType> args) {
+        var segments = new ArrayList<>(this.segments);
+        var lastSegment = segments.removeLast().withArgs(args);
+        segments.add(lastSegment);
+        return new RustTypePath(segments);
+    }
     // Custom area end: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePath body
 }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustTypePathSegment.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustTypePathSegment.java
index cbd1c69..4473aa3 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustTypePathSegment.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustTypePathSegment.java
@@ -5,22 +5,29 @@ package org.zwobble.hobgoblin.compiler.output.lang.rust.ast;
 // Custom area start: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment imports
 // Custom area end: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment imports
 
-public record RustTypePathSegment(org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustPathIdentSegment pathIdentSegment) {
+import java.util.List;
+import java.util.Optional;
+
+public record RustTypePathSegment(org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustPathIdentSegment pathIdentSegment, java.util.Optional<java.util.List<org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustType>> args) {
     public static org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment.Builder arbitrary() {
-        return new org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment.Builder(org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustPathIdentSegmentIdentifier.arbitrary().build());
+        return new org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment.Builder(org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustPathIdentSegmentIdentifier.arbitrary().build(), java.util.Optional.empty());
     }
 
-    public record Builder(org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustPathIdentSegment pathIdentSegment) {
+    public record Builder(org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustPathIdentSegment pathIdentSegment, java.util.Optional<java.util.List<org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustType>> args) {
         public org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment build() {
-            return new org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment(pathIdentSegment);
+            return new org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment(pathIdentSegment, args);
         }
 
         public org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment.Builder withPathIdentSegment(org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustPathIdentSegment pathIdentSegment) {
-            return new org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment.Builder(pathIdentSegment);
+            return new org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment.Builder(pathIdentSegment, args);
         }
 
         public org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment.Builder withPathIdentSegment(org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustPathIdentSegment.Builder pathIdentSegment) {
-            return new org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment.Builder(pathIdentSegment.build());
+            return new org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment.Builder(pathIdentSegment.build(), args);
+        }
+
+        public org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment.Builder withArgs(java.util.Optional<java.util.List<org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustType>> args) {
+            return new org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment.Builder(pathIdentSegment, args);
         }
 
         // Custom area start: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment.Builder body
@@ -28,5 +35,12 @@ public record RustTypePathSegment(org.zwobble.hobgoblin.compiler.output.lang.rus
     }
 
     // Custom area start: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment body
+    public RustTypePathSegment withArgs(List<RustType> args) {
+        if (this.args.isPresent()) {
+            throw new IllegalArgumentException("Type path segment already has args");
+        }
+
+        return new RustTypePathSegment(this.pathIdentSegment, Optional.of(args));
+    }
     // Custom area end: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustTypePathSegment body
 }
-- 
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