From 33177f7ce84e8e4163d99a45a1df1959b8ea857c Mon Sep 17 00:00:00 2001
From: Xi Ge <xi_ge@apple.com>
Date: Wed, 11 Aug 2021 11:12:32 -0700
Subject: [PATCH] Put default interface verifier behind an env var

Without setting this variable, we won't enable module interface verifier unless
explicitly asked to.
---
 Sources/SwiftDriver/Jobs/Planning.swift       |  6 +++++
 Tests/SwiftDriverTests/SwiftDriverTests.swift | 22 ++++++++++++++-----
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/Sources/SwiftDriver/Jobs/Planning.swift b/Sources/SwiftDriver/Jobs/Planning.swift
index 652b035c9..48b2d4a08 100644
--- a/Sources/SwiftDriver/Jobs/Planning.swift
+++ b/Sources/SwiftDriver/Jobs/Planning.swift
@@ -439,6 +439,12 @@ extension Driver {
                               default: false)
     else { return }
 
+    // FIXME: remove this when we are confident to enable interface verification
+    // by default.
+    if env["ENABLE_DEFAULT_INTERFACE_VERIFIER"] == nil &&
+        !parsedOptions.hasArgument(.verifyEmittedModuleInterface) {
+      return
+    }
     func addVerifyJob(forPrivate: Bool) throws {
       let isNeeded =
         forPrivate
diff --git a/Tests/SwiftDriverTests/SwiftDriverTests.swift b/Tests/SwiftDriverTests/SwiftDriverTests.swift
index e2c96233b..2a7b30e3c 100644
--- a/Tests/SwiftDriverTests/SwiftDriverTests.swift
+++ b/Tests/SwiftDriverTests/SwiftDriverTests.swift
@@ -3940,6 +3940,8 @@ final class SwiftDriverTests: XCTestCase {
 
   func testVerifyEmittedInterfaceJob() throws {
     // Evolution enabled
+    var envVars = ProcessEnv.vars
+    envVars["ENABLE_DEFAULT_INTERFACE_VERIFIER"] = "YES"
     do {
       var driver = try Driver(args: ["swiftc", "foo.swift", "-emit-module", "-module-name",
                                      "foo", "-emit-module-interface",
@@ -3965,7 +3967,7 @@ final class SwiftDriverTests: XCTestCase {
     // No Evolution
     do {
       var driver = try Driver(args: ["swiftc", "foo.swift", "-emit-module", "-module-name",
-                                     "foo", "-emit-module-interface", "-verify-emitted-module-interface"])
+                                     "foo", "-emit-module-interface", "-verify-emitted-module-interface"], env: envVars)
       let plannedJobs = try driver.planBuild()
       XCTAssertEqual(plannedJobs.count, 2)
     }
@@ -3975,7 +3977,7 @@ final class SwiftDriverTests: XCTestCase {
       var driver = try Driver(args: ["swiftc", "foo.swift", "-emit-module", "-module-name",
                                      "foo", "-emit-module-interface",
                                      "-enable-library-evolution",
-                                     "-no-verify-emitted-module-interface"])
+                                     "-no-verify-emitted-module-interface"], env: envVars)
       let plannedJobs = try driver.planBuild()
       XCTAssertEqual(plannedJobs.count, 2)
     }
@@ -3985,18 +3987,28 @@ final class SwiftDriverTests: XCTestCase {
       var driver = try Driver(args: ["swiftc", "foo.swift", "-emit-module", "-module-name",
                                      "foo", "-emit-module-interface",
                                      "-enable-library-evolution",
-                                     "-no-emit-module-separately"])
+                                     "-no-emit-module-separately"], env: envVars)
       let plannedJobs = try driver.planBuild()
       XCTAssertEqual(plannedJobs.count, 2)
     }
 
-    // Emit-module separately
+    // Disabled when no "ENABLE_DEFAULT_INTERFACE_VERIFIER" found in the environment
     do {
       var driver = try Driver(args: ["swiftc", "foo.swift", "-emit-module", "-module-name",
                                      "foo", "-emit-module-interface",
                                      "-enable-library-evolution",
                                      "-experimental-emit-module-separately"])
       let plannedJobs = try driver.planBuild()
+      XCTAssertEqual(plannedJobs.count, 1)
+    }
+
+    // Emit-module separately
+    do {
+      var driver = try Driver(args: ["swiftc", "foo.swift", "-emit-module", "-module-name",
+                                     "foo", "-emit-module-interface",
+                                     "-enable-library-evolution",
+                                     "-experimental-emit-module-separately"], env: envVars)
+      let plannedJobs = try driver.planBuild()
       XCTAssertEqual(plannedJobs.count, 2)
       let emitJob = plannedJobs[0]
       let verifyJob = plannedJobs[1]
@@ -4015,7 +4027,7 @@ final class SwiftDriverTests: XCTestCase {
       var driver = try Driver(args: ["swiftc", "foo.swift", "-emit-module", "-module-name",
                                      "foo", "-emit-module-interface",
                                      "-enable-library-evolution",
-                                     "-whole-module-optimization"])
+                                     "-whole-module-optimization"], env: envVars)
       let plannedJobs = try driver.planBuild()
       XCTAssertEqual(plannedJobs.count, 2)
       let emitJob = plannedJobs[0]