misc/ios: add support for running programs on the iOS simulator

Update the README to mention the emulator. Remove reference to gomobile
while here; there are multiple ways to develop for iOS today, including
using the c-archive buildmode directly.

Updates golang#38485

Change-Id: Iccef75e646ea8e1b9bc3fc37419cc2d6bf3dfdf4
Reviewed-on: https://go-review.googlesource.com/c/go/+/255257
Run-TryBot: Elias Naur <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Trust: Elias Naur <[email protected]>
Reviewed-by: Cherry Zhang <[email protected]>

misc/ios/README

@@ -1,13 +1,20 @@
 Go on iOS
 =========
 
-For details on developing Go for iOS on macOS, see the documentation in the mobile
-subrepository:
+To run the standard library tests, run all.bash as usual, but with the compiler
+set to the clang wrapper that invokes clang for iOS. For example, this command runs
+ all.bash on the iOS emulator:
 
-    https://github.com/golang/mobile
+	GOOS=ios GOARCH=amd64 CGO_ENABLED=1 CC_FOR_TARGET=$(pwd)/../misc/ios/clangwrap.sh ./all.bash
 
-It is necessary to set up the environment before running tests or programs directly on a
-device.
+To use the go tool to run individual programs and tests, put $GOROOT/bin into PATH to ensure
+the go_ios_$GOARCH_exec wrapper is found. For example, to run the archive/tar tests:
+
+	export PATH=$GOROOT/bin:$PATH
+	GOOS=ios GOARCH=amd64 CGO_ENABLED=1 go test archive/tar
+
+The go_ios_exec wrapper uses GOARCH to select the emulator (amd64) or the device (arm64).
+However, further setup is required to run tests or programs directly on a device.
 
 First make sure you have a valid developer certificate and have setup your device properly
 to run apps signed by your developer certificate. Then install the libimobiledevice and
@@ -29,18 +36,10 @@ which will output something similar to
 	export GOIOS_TEAM_ID=ZZZZZZZZ
 
 If you have multiple devices connected, specify the device UDID with the GOIOS_DEVICE_ID
-variable. Use `idevice_id -l` to list all available UDIDs.
-
-Finally, to run the standard library tests, run all.bash as usual, but with the compiler
-set to the clang wrapper that invokes clang for iOS. For example,
+variable. Use `idevice_id -l` to list all available UDIDs. Then, setting GOARCH to arm64
+will select the device:
 
-	GOARCH=arm64 CGO_ENABLED=1 CC_FOR_TARGET=$(pwd)/../misc/ios/clangwrap.sh ./all.bash
-
-To use the go tool directly to run programs and tests, put $GOROOT/bin into PATH to ensure
-the go_darwin_$GOARCH_exec wrapper is found. For example, to run the archive/tar tests
-
-	export PATH=$GOROOT/bin:$PATH
-	GOARCH=arm64 CGO_ENABLED=1 go test archive/tar
+	GOOS=ios GOARCH=arm64 CGO_ENABLED=1 CC_FOR_TARGET=$(pwd)/../misc/ios/clangwrap.sh ./all.bash
 
 Note that the go_darwin_$GOARCH_exec wrapper uninstalls any existing app identified by
 the bundle id before installing a new app. If the uninstalled app is the last app by

misc/ios/clangwrap.sh

@@ -2,17 +2,19 @@
 # This uses the latest available iOS SDK, which is recommended.
 # To select a specific SDK, run 'xcodebuild -showsdks'
 # to see the available SDKs and replace iphoneos with one of them.
-SDK=iphoneos
-SDK_PATH=`xcrun --sdk $SDK --show-sdk-path`
-export IPHONEOS_DEPLOYMENT_TARGET=5.1
-# cmd/cgo doesn't support llvm-gcc-4.2, so we have to use clang.
-CLANG=`xcrun --sdk $SDK --find clang`
-
 if [ "$GOARCH" == "arm64" ]; then
+	SDK=iphoneos
+	PLATFORM=ios
 	CLANGARCH="arm64"
 else
-	echo "unknown GOARCH=$GOARCH" >&2
-	exit 1
+	SDK=iphonesimulator
+	PLATFORM=ios-simulator
+	CLANGARCH="x86_64"
 fi
 
-exec "$CLANG" -arch $CLANGARCH -isysroot "$SDK_PATH" -mios-version-min=10.0 "$@"
+SDK_PATH=`xcrun --sdk $SDK --show-sdk-path`
+export IPHONEOS_DEPLOYMENT_TARGET=5.1
+# cmd/cgo doesn't support llvm-gcc-4.2, so we have to use clang.
+CLANG=`xcrun --sdk $SDK --find clang`
+
+exec "$CLANG" -arch $CLANGARCH -isysroot "$SDK_PATH" -m${PLATFORM}-version-min=10.0 "$@"

misc/ios/detect.go

@@ -6,7 +6,7 @@
 
 // detect attempts to autodetect the correct
 // values of the environment variables
-// used by go_darwin_arm_exec.
+// used by go_io_exec.
 // detect shells out to ideviceinfo, a third party program that can
 // be obtained by following the instructions at
 // https://github.com/libimobiledevice/libimobiledevice.