[migrator] Migrate UIApplicationMain

In Swift 4.2 the second parameter of UIApplicationMain exactly matches the type
of CommandLine.unsafeArgv so it can be called as below:

UIApplicationMain(CommandLine.argc, CommandLine.unsafeArgv, ...)

This is how it was intended to be in Swift 4 as well, but the types had
optionality differences, so callers instead had to do something like the below
example from the Firefox-iOS project:

let pointer = UnsafeMutableRawPointer(CommandLine.unsafeArgv).bindMemory(
    to: UnsafeMutablePointer<Int8>.self, capacity: Int(CommandLine.argc))
UIApplicationMain(CommandLine.argc, pointer, ...)

This migration simply replaces the the second argument with
CommandLine.unsafeArgv if the first argument is CommandLine.argc.

There is an open issue for providing a deprecated version with the old type so
we simply leave as is any callers that don't pass argc for the first argument.

Resolves rdar://problem/40045693.

Author: Nathan Hawes

include/swift/IDE/DigesterEnums.def

@@ -172,6 +172,7 @@ SPECIAL_CASE_ID(StaticAbsToSwiftAbs)
 SPECIAL_CASE_ID(NSOpenGLGetVersion)
 SPECIAL_CASE_ID(ToIntMax)
 SPECIAL_CASE_ID(ToUIntMax)
+SPECIAL_CASE_ID(UIApplicationMain)
 
 #undef SPECIAL_CASE_ID
 #undef DIFF_ITEM_KEY_KIND_INT

lib/Migrator/APIDiffMigratorPass.cpp

@@ -675,6 +675,23 @@ struct APIDiffMigratorPass : public ASTMigratorPass, public SourceEntityWalker {
       }
       return false;
     }
+    case SpecialCaseId::UIApplicationMain: {
+      // If the first argument is CommandLine.argc, replace the second argument
+      // with CommandLine.unsafeArgv
+      CallArgInfo &FirstArg = AllArgs[0];
+      // handle whitespace/line splits around the first arg when matching
+      auto FirstArgSplit =
+        SM.extractText(FirstArg.getEntireCharRange(SM)).rsplit('.');
+      if (!FirstArgSplit.second.empty() &&
+          FirstArgSplit.first.trim() == "CommandLine" &&
+          FirstArgSplit.second.trim() == "argc") {
+        CallArgInfo &SecondArg = AllArgs[1];
+        Editor.replace(SecondArg.getEntireCharRange(SM),
+                       "CommandLine.unsafeArgv");
+        return true;
+      }
+      return false;
+    }
     }
   }
 

lib/Migrator/overlay3.json

@@ -1316,4 +1316,9 @@
     "RightComment": "compactMap",
     "ModuleName": "Swift"
   },
+  {
+    "DiffItemKind": "SpecialCaseDiffItem",
+    "Usr": "c:@F@UIApplicationMain",
+    "SpecialCaseId": "UIApplicationMain"
+  }
 ]

lib/Migrator/overlay4.json

@@ -1316,4 +1316,9 @@
     "RightComment": "compactMap",
     "ModuleName": "Swift"
   },
+  {
+    "DiffItemKind": "SpecialCaseDiffItem",
+    "Usr": "c:@F@UIApplicationMain",
+    "SpecialCaseId": "UIApplicationMain"
+  }
 ]

test/Migrator/Inputs/MyAppKit.swift

@@ -2,3 +2,4 @@
 public class NSOpenGLOption {}
 public func NSOpenGLGetOption(_ c : NSOpenGLOption, _ p :UnsafePointer<Int>) {}
 public func NSOpenGLSetOption(_ c : NSOpenGLOption, _ p : Int) {}
+public func UIApplicationMain(_ a: Int32, _ b: UnsafeMutablePointer<UnsafeMutablePointer<Int8>>, _ c: String?, _ d: String?) -> Int32 { return 0 }

test/Migrator/Inputs/SpecialCaseAPI.json

@@ -13,5 +13,10 @@
     "DiffItemKind": "SpecialCaseDiffItem",
     "Usr": "s:7MySwift0A6DoubleV3absyS2dFZ",
     "SpecialCaseId": "StaticAbsToSwiftAbs"
+  },
+  {
+    "DiffItemKind": "SpecialCaseDiffItem",
+    "Usr": "s:8MyAppKit17UIApplicationMainys5Int32VAD_SpySpys4Int8VGGSSSgAItF",
+    "SpecialCaseId": "UIApplicationMain"
   }
 ]

test/Migrator/api-special-cases.swift

@@ -8,10 +8,16 @@
 import MyAppKit
 import MySwift
 
-func foo(_ Opt: NSOpenGLOption) {
+func foo(_ Opt: NSOpenGLOption, _ pointer: UnsafeMutablePointer<UnsafeMutablePointer<Int8>>) {
   var Value = 1
   NSOpenGLSetOption(Opt, 1)
   NSOpenGLGetOption(Opt, &Value)
+  UIApplicationMain(CommandLine.argc, pointer, "", "")
+  UIApplicationMain(
+    CommandLine.argc, pointer, "", "")
+  UIApplicationMain( CommandLine . 
+    argc, pointer, "", "")
+  UIApplicationMain(10, pointer, "", "")
 }
 
 do {

test/Migrator/api-special-cases.swift.expected

@@ -8,10 +8,16 @@
 import MyAppKit
 import MySwift
 
-func foo(_ Opt: NSOpenGLOption) {
+func foo(_ Opt: NSOpenGLOption, _ pointer: UnsafeMutablePointer<UnsafeMutablePointer<Int8>>) {
   var Value = 1
   Opt.globalValue = 1
   Value = Opt.globalValue
+  UIApplicationMain(CommandLine.argc, CommandLine.unsafeArgv, "", "")
+  UIApplicationMain(
+    CommandLine.argc, CommandLine.unsafeArgv, "", "")
+  UIApplicationMain( CommandLine . 
+    argc, CommandLine.unsafeArgv, "", "")
+  UIApplicationMain(10, pointer, "", "")
 }
 
 do {

test/Migrator/ui-application-main.swift

@@ -0,0 +1,14 @@
+// RUN: %empty-directory(%t) && %target-swift-frontend -c -update-code -primary-file %s -emit-migrated-file-path %t/ui-application-main.swift.result -emit-remap-file-path %t/ui-application-main.swift.remap -o /dev/null -swift-version 3
+// RUN: diff -u %S/ui-application-main.swift.expected %t/ui-application-main.swift.result
+// RUN: %empty-directory(%t) && %target-swift-frontend -c -update-code -primary-file %s -emit-migrated-file-path %t/ui-application-main.swift.result -emit-remap-file-path %t/ui-application-main.swift.remap -o /dev/null -swift-version 4
+// RUN: diff -u %S/ui-application-main.swift.expected %t/ui-application-main.swift.result
+
+// REQUIRES: OS=ios
+// REQUIRES: objc_interop
+
+import UIKit
+
+func foo(pointer: UnsafeMutablePointer<UnsafeMutablePointer<Int8>>) {
+	UIApplicationMain(CommandLine.argc, pointer, "", "")
+	UIApplicationMain(2, pointer, "", "")
+}

test/Migrator/ui-application-main.swift.expected

@@ -0,0 +1,14 @@
+// RUN: %empty-directory(%t) && %target-swift-frontend -c -update-code -primary-file %s -emit-migrated-file-path %t/ui-application-main.swift.result -emit-remap-file-path %t/ui-application-main.swift.remap -o /dev/null -swift-version 3
+// RUN: diff -u %S/ui-application-main.swift.expected %t/ui-application-main.swift.result
+// RUN: %empty-directory(%t) && %target-swift-frontend -c -update-code -primary-file %s -emit-migrated-file-path %t/ui-application-main.swift.result -emit-remap-file-path %t/ui-application-main.swift.remap -o /dev/null -swift-version 4
+// RUN: diff -u %S/ui-application-main.swift.expected %t/ui-application-main.swift.result
+
+// REQUIRES: OS=ios
+// REQUIRES: objc_interop
+
+import UIKit
+
+func foo(pointer: UnsafeMutablePointer<UnsafeMutablePointer<Int8>>) {
+	UIApplicationMain(CommandLine.argc, CommandLine.unsafeArgv, "", "")
+	UIApplicationMain(2, pointer, "", "")
+}