From 140c82e012af2f8204b5828cf0c5d023d467df96 Mon Sep 17 00:00:00 2001
From: Jake Bailey <5341706+jakebailey@users.noreply.github.com>
Date: Mon, 27 Apr 2026 18:55:18 -0700
Subject: [PATCH] compiler: disambiguate generic instance link names with local
 type args

---
 compiler/goroutine.go   |  4 ++--
 compiler/symbol.go      | 26 ++++++++++++++++++++++++++
 testdata/localtypes.txt |  6 +++---
 3 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/compiler/goroutine.go b/compiler/goroutine.go
index 30c8ef242..6b1a19edd 100644
--- a/compiler/goroutine.go
+++ b/compiler/goroutine.go
@@ -97,7 +97,7 @@ func (b *builder) createGo(instr *ssa.Go) {
 		funcType = b.getLLVMFunctionType(instr.Call.Value.Type().Underlying().(*types.Signature))
 		params = append(params, context, funcPtr)
 		hasContext = true
-		prefix = b.fn.RelString(nil)
+		prefix = b.getFunctionInfo(b.fn).linkName
 	}
 
 	paramBundle := b.emitPointerPack(params)
@@ -139,7 +139,7 @@ func (b *builder) createWasmExport() {
 	// Declare the exported function.
 	paramTypes := b.llvmFnType.ParamTypes()
 	exportedFnType := llvm.FunctionType(b.llvmFnType.ReturnType(), paramTypes[:len(paramTypes)-1], false)
-	exportedFn := llvm.AddFunction(b.mod, b.fn.RelString(nil)+suffix, exportedFnType)
+	exportedFn := llvm.AddFunction(b.mod, b.getFunctionInfo(b.fn).linkName+suffix, exportedFnType)
 	b.addStandardAttributes(exportedFn)
 	llvmutil.AppendToGlobal(b.mod, "llvm.used", exportedFn)
 	exportedFn.AddFunctionAttr(b.ctx.CreateStringAttribute("wasm-export-name", b.info.wasmExport))
diff --git a/compiler/symbol.go b/compiler/symbol.go
index 9076e870d..d6f680c3f 100644
--- a/compiler/symbol.go
+++ b/compiler/symbol.go
@@ -323,6 +323,12 @@ func (c *compilerContext) getFunctionInfo(f *ssa.Function) functionInfo {
 		linkName: f.RelString(nil),
 	}
 
+	// RelString is not unique for local type arguments, so add a suffix
+	// when needed.
+	if suffix := c.localTypeArgsSuffix(f); suffix != "" {
+		info.linkName += suffix
+	}
+
 	// Check for a few runtime functions that are treated specially.
 	if info.linkName == "runtime.wasmEntryReactor" && c.BuildMode == "c-shared" {
 		info.linkName = "_initialize"
@@ -347,6 +353,26 @@ func (c *compilerContext) getFunctionInfo(f *ssa.Function) functionInfo {
 	return info
 }
 
+func (c *compilerContext) localTypeArgsSuffix(f *ssa.Function) string {
+	typeArgs := f.TypeArgs()
+	if len(typeArgs) == 0 {
+		return ""
+	}
+	var hasLocal bool
+	parts := make([]string, len(typeArgs))
+	for i, ta := range typeArgs {
+		name, isLocal := c.getTypeCodeName(ta)
+		if isLocal {
+			hasLocal = true
+		}
+		parts[i] = name
+	}
+	if !hasLocal {
+		return ""
+	}
+	return "$localtype:" + strings.Join(parts, ",")
+}
+
 // parsePragmas is used by getFunctionInfo to parse function pragmas such as
 // //export or //go:noinline.
 func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
diff --git a/testdata/localtypes.txt b/testdata/localtypes.txt
index f42fafad6..dd5d72ddd 100644
--- a/testdata/localtypes.txt
+++ b/testdata/localtypes.txt
@@ -42,8 +42,8 @@ ok: doublyNestedInGeneric[string].Y accepts own
 ok: doublyNestedInGeneric[int].Y rejects [string].Y
 ok: doublyNestedInGeneric[string].Y rejects [int].Y
 issue4931A labels: 0
-issue4931B labels: 1
+issue4931B labels: 0
 issue4931PairA labels: 0
-issue4931PairB labels: 1
+issue4931PairB labels: 0
 issue4931MethodA labels: 0
-issue4931MethodB labels: 1
+issue4931MethodB labels: 0