WIP fix for duplicate columns in bun:sql

src/bun.js/bindings/SQLClient.cpp

@@ -1,5 +1,8 @@
+
 #include "root.h"
 
+#include "helpers.h"
+#include "JavaScriptCore/JSObject.h"
 #include "JavaScriptCore/JSGlobalObject.h"
 #include <JavaScriptCore/StructureInlines.h>
 #include <JavaScriptCore/ObjectPrototype.h>
@@ -266,7 +269,20 @@ extern "C" EncodedJSValue JSC__constructObjectFromDataCell(
 extern "C" EncodedJSValue JSC__createStructure(JSC::JSGlobalObject* globalObject, JSC::JSCell* owner, unsigned int inlineCapacity, BunString* names)
 {
     auto& vm = globalObject->vm();
-    Structure* structure = globalObject->structureCache().emptyObjectStructureForPrototype(globalObject, globalObject->objectPrototype(), inlineCapacity);
+    PropertyNameArray propertyNames(vm, PropertyNameMode::Strings, PrivateSymbolMode::Exclude);
+    unsigned int totalCount = inlineCapacity;
+    for (unsigned i = 0; i < totalCount; i++) {
+        auto initialCount = propertyNames.size();
+        propertyNames.add(Identifier::fromString(vm, names[i].toWTFString()));
+
+        // Handle duplicates
+        if (UNLIKELY(propertyNames.size() == initialCount)) {
+            names[i].deref();
+            names[i] = BunStringEmpty;
+        }
+    }
+
+    Structure* structure = globalObject->structureCache().emptyObjectStructureForPrototype(globalObject, globalObject->objectPrototype(), std::min(static_cast<unsigned>(propertyNames.size()), JSFinalObject::maxInlineCapacity));
     if (owner) {
         vm.writeBarrier(owner, structure);
     } else {
@@ -274,14 +290,10 @@ extern "C" EncodedJSValue JSC__createStructure(JSC::JSGlobalObject* globalObject
     }
     ensureStillAliveHere(structure);
 
-    PropertyNameArray propertyNames(vm, PropertyNameMode::Strings, PrivateSymbolMode::Exclude);
-    for (unsigned i = 0; i < inlineCapacity; i++) {
-        propertyNames.add(Identifier::fromString(vm, names[i].toWTFString()));
-    }
-
     PropertyOffset offset = 0;
-    for (unsigned i = 0; i < inlineCapacity; i++) {
-        structure = structure->addPropertyTransition(vm, structure, propertyNames[i], 0, offset);
+
+    for (const auto& name : propertyNames) {
+        structure = structure->addPropertyTransition(vm, structure, name, 0, offset);
     }
 
     return JSValue::encode(structure);

src/sql/postgres.zig

@@ -930,6 +930,7 @@ pub const protocol = struct {
         table_oid: int4 = 0,
         column_index: short = 0,
         type_oid: int4 = 0,
+        is_duplicate_column: bool = false,
 
         pub fn typeTag(this: @This()) types.Tag {
             return @enumFromInt(@as(short, @truncate(this.type_oid)));
@@ -969,10 +970,10 @@ pub const protocol = struct {
     };
 
     pub const RowDescription = struct {
-        fields: []const FieldDescription = &[_]FieldDescription{},
+        fields: []FieldDescription = &[_]FieldDescription{},
         pub fn deinit(this: *@This()) void {
             for (this.fields) |*field| {
-                @constCast(field).deinit();
+                field.deinit();
             }
 
             bun.default_allocator.free(this.fields);
@@ -4062,7 +4063,7 @@ pub const PostgresSQLConnection = struct {
 pub const PostgresSQLStatement = struct {
     cached_structure: JSC.Strong = .{},
     ref_count: u32 = 1,
-    fields: []const protocol.FieldDescription = &[_]protocol.FieldDescription{},
+    fields: []protocol.FieldDescription = &[_]protocol.FieldDescription{},
     parameters: []const int4 = &[_]int4{},
     signature: Signature,
     status: Status = Status.parsing,
@@ -4107,7 +4108,10 @@ pub const PostgresSQLStatement = struct {
         return this.cached_structure.get() orelse {
             const names = bun.default_allocator.alloc(bun.String, this.fields.len) catch return .undefined;
             defer {
-                for (names) |*name| {
+                for (names, this.fields) |*name, *field| {
+                    if (name.isEmpty()) {
+                        field.is_duplicate_column = true;
+                    }
                     name.deref();
                 }
                 bun.default_allocator.free(names);
@@ -4121,6 +4125,7 @@ pub const PostgresSQLStatement = struct {
                 @truncate(this.fields.len),
                 names.ptr,
             );
+
             this.cached_structure.set(globalObject, structure_);
             return structure_;
         };

test/js/sql/sql.test.ts

@@ -88,6 +88,11 @@ if (!isCI) {
     await sql`drop table test`;
   });
 
+  test("Duplicate columns", async () => {
+    const [{ x }] = await sql`select 1 as x, 2 as x`;
+    expect(x).toBe(1);
+  });
+
   test("Drop table", async () => {
     await sql`create table test(int int)`;
     await sql`drop table test`;