From 5f40a1bf751459341b61de757a4eee203eb04172 Mon Sep 17 00:00:00 2001
From: Jan Kassens <jkassens@meta.com>
Date: Mon, 14 Nov 2022 11:35:47 -0500
Subject: [PATCH] [bug] fix codegen for LVals with memberPath (#772)

---
 compiler/forget/src/HIR/Codegen.ts                     | 10 +++++++++-
 .../fixtures/hir/assignment-variations.expect.md       |  4 ++--
 .../hir/mutable-lifetime-with-aliasing.expect.md       |  2 +-
 .../fixtures/hir/property-assignment.expect.md         |  2 +-
 .../src/__tests__/fixtures/hir/ssa-property.expect.md  |  2 +-
 5 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/compiler/forget/src/HIR/Codegen.ts b/compiler/forget/src/HIR/Codegen.ts
index 16b6a95de6..7249f65102 100644
--- a/compiler/forget/src/HIR/Codegen.ts
+++ b/compiler/forget/src/HIR/Codegen.ts
@@ -745,7 +745,15 @@ function codegenJsxElement(
 }
 
 function codegenLVal(lval: LValue): t.LVal {
-  return convertIdentifier(lval.place.identifier);
+  const expr = convertIdentifier(lval.place.identifier);
+  const memberPath = lval.place.memberPath;
+  return memberPath == null
+    ? expr
+    : memberPath.reduceRight(
+        (path: t.Identifier | t.MemberExpression, member) =>
+          t.memberExpression(path, t.identifier(member)),
+        expr
+      );
 }
 
 function codegenValue(
diff --git a/compiler/forget/src/__tests__/fixtures/hir/assignment-variations.expect.md b/compiler/forget/src/__tests__/fixtures/hir/assignment-variations.expect.md
index 2817fd9b69..b5baec5f97 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/assignment-variations.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/assignment-variations.expect.md
@@ -98,8 +98,8 @@ flowchart TB
 
 ```javascript
 function g$0(a$4) {
-  a$4 = a$4.b.c + 1;
-  a$4 = a$4.b.c * 2;
+  a$4.c.b = a$4.b.c + 1;
+  a$4.c.b = a$4.b.c * 2;
   return;
 }
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-with-aliasing.expect.md b/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-with-aliasing.expect.md
index 180b99ba2e..e2c8ea2be1 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-with-aliasing.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-with-aliasing.expect.md
@@ -156,7 +156,7 @@ function Component$0(props$10) {
     c: c$13,
   };
   const x$15 = {};
-  x$15 = b$12;
+  x$15.b = b$12;
   const y$16 = mutate$8(x$15, d$14);
   a$11;
   b$12;
diff --git a/compiler/forget/src/__tests__/fixtures/hir/property-assignment.expect.md b/compiler/forget/src/__tests__/fixtures/hir/property-assignment.expect.md
index 1f534c8745..bb39788d38 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/property-assignment.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/property-assignment.expect.md
@@ -53,7 +53,7 @@ flowchart TB
 function Component$0(props$6) {
   const x$7 = {};
   const y$8 = [];
-  x$7 = y$8;
+  x$7.y = y$8;
   const child$9 = <Component$0 data={y$8}></Component$0>;
   x$7.y.push(props$6.p0);
   return <Component$0 data={x$7}>{child$9}</Component$0>;
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-property.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-property.expect.md
index 2f2802774b..9d5f790b60 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-property.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-property.expect.md
@@ -45,7 +45,7 @@ flowchart TB
 function foo$0() {
   const x$3 = [];
   const y$4 = {};
-  y$4 = x$3;
+  y$4.x = x$3;
   return y$4;
 }