From 6563c99c4937d31478b62601fb02479ac8f830cf Mon Sep 17 00:00:00 2001
From: Nicola Corti <ncor@fb.com>
Date: Mon, 25 Apr 2022 12:15:41 -0700
Subject: [PATCH] Honor the REACT_NATIVE_OVERRIDE_HERMES_DIR variable when
 searching for `hermesc`

Summary:
When searching for the `hermesc` path, we should also honor the `REACT_NATIVE_OVERRIDE_HERMES_DIR` variable.

Changelog:
[Internal] [Changed] - Honor the REACT_NATIVE_OVERRIDE_HERMES_DIR variable when searching for `hermesc`

Reviewed By: neildhar

Differential Revision: D35903601

fbshipit-source-id: 31e1255a558eece8cd84669861328db72e9ed17b
---
 .../com/facebook/react/utils/PathUtils.kt      | 18 +++++++++++++++++-
 .../com/facebook/react/utils/PathUtilsTest.kt  | 14 ++++++++++++++
 react.gradle                                   |  5 ++++-
 3 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/packages/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/utils/PathUtils.kt b/packages/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/utils/PathUtils.kt
index 594bc267d2a..6915cc679c1 100644
--- a/packages/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/utils/PathUtils.kt
+++ b/packages/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/utils/PathUtils.kt
@@ -129,7 +129,8 @@ internal fun detectOSAwareHermesCommand(projectRoot: File, hermesCommand: String
   }
 
   // 2. If the project is building hermes-engine from source, use hermesc from there
-  val builtHermesc = File(projectRoot, HERMESC_BUILT_FROM_SOURCE_PATH)
+  val builtHermesc =
+      getBuiltHermescFile(projectRoot, System.getenv("REACT_NATIVE_OVERRIDE_HERMES_DIR"))
   if (builtHermesc.exists()) {
     return builtHermesc.absolutePath
   }
@@ -151,6 +152,21 @@ internal fun detectOSAwareHermesCommand(projectRoot: File, hermesCommand: String
           "node_modules/react-native/sdks/hermesc/%OS-BIN%/hermesc")
 }
 
+/**
+ * Gets the location where Hermesc should be. If nothing is specified, built hermesc is assumed to
+ * be inside [HERMESC_BUILT_FROM_SOURCE_PATH]. Otherwise user can specify an override with
+ * [pathOverride], which is assumed to be an absolute path where Hermes source code is
+ * provided/built.
+ *
+ * @param projectRoot The root of the Project.
+ */
+internal fun getBuiltHermescFile(projectRoot: File, pathOverride: String?) =
+    if (!pathOverride.isNullOrBlank()) {
+      File(pathOverride, "build/bin/hermesc")
+    } else {
+      File(projectRoot, HERMESC_BUILT_FROM_SOURCE_PATH)
+    }
+
 internal fun getHermesOSBin(): String {
   if (Os.isWindows()) return "win64-bin"
   if (Os.isMac()) return "osx-bin"
diff --git a/packages/react-native-gradle-plugin/src/test/kotlin/com/facebook/react/utils/PathUtilsTest.kt b/packages/react-native-gradle-plugin/src/test/kotlin/com/facebook/react/utils/PathUtilsTest.kt
index fafc7ceda4b..34e10cb4cb9 100644
--- a/packages/react-native-gradle-plugin/src/test/kotlin/com/facebook/react/utils/PathUtilsTest.kt
+++ b/packages/react-native-gradle-plugin/src/test/kotlin/com/facebook/react/utils/PathUtilsTest.kt
@@ -231,4 +231,18 @@ class PathUtilsTest {
 
     assertEquals(expected.toString(), detectOSAwareHermesCommand(tempFolder.root, ""))
   }
+
+  @Test
+  fun getBuiltHermescFile_withoutOverride() {
+    assertEquals(
+        File(tempFolder.root, "node_modules/react-native/sdks/hermes/build/bin/hermesc"),
+        getBuiltHermescFile(tempFolder.root, ""))
+  }
+
+  @Test
+  fun getBuiltHermescFile_withOverride() {
+    assertEquals(
+        File("/home/circleci/hermes/build/bin/hermesc"),
+        getBuiltHermescFile(tempFolder.root, "/home/circleci/hermes"))
+  }
 }
diff --git a/react.gradle b/react.gradle
index f3c098fdc86..c7ad3db8936 100644
--- a/react.gradle
+++ b/react.gradle
@@ -103,7 +103,10 @@ def getHermesCommand = {
     }
 
     // 2. If the project is building hermes-engine from source, use hermesc from there
-    def builtHermesc = new File(reactRoot, "node_modules/react-native/sdks/hermes/build/bin/hermesc")
+    // Also note that user can override the hermes source location with
+    // the `REACT_NATIVE_OVERRIDE_HERMES_DIR` env variable.
+    def hermesOverrideDir = System.getenv("REACT_NATIVE_OVERRIDE_HERMES_DIR")
+    def builtHermesc = hermesOverrideDir ? new File(hermesOverrideDir, "build/bin/hermesc") : new File(reactRoot, "node_modules/react-native/sdks/hermes/build/bin/hermesc")
     if (builtHermesc.exists()) {
         return builtHermesc.getAbsolutePath()
     }