Avoid clean on running xcodebuild if New Build System is used.

[norio-nomura]

Since Xcode’s New Build System uses llbuild, compiler arguments for Module can be retrieved from manifest of llbuild instead of parsing xcodebuild’s output. Until this changes, the clean action was used for xcodebuild to ensure compiler arguments, but it is not necessary when using the New Build System.

[jpsim]

This is promising, thank you! Although there's one slight problem: -showBuildSettings doesn't generate the manifest file, so if derived data is empty, it will still run a full build.

However, @keith recently discovered that even though xcodebuild -dry-run isn't technically supported with the llbuild-based build system, and running the command returns a non-zero exit code, the manifest file is still correctly generated.

So we could solve this by running -dry-run and ignore the result before continuing with checkNewBuildSystem.

But we still need a full build afterwards, because otherwise we get some types that resolve as <<error type>>, so we'd need to revert 4f130be.

 internal func checkNewBuildSystem(xcodeBuildArguments: [String],
                                   moduleName: String? = nil,
                                   inPath path: String) -> [String]? {
-    // Check `PROJECT_TEMP_ROOT`
+    // `-dry-run` generates the manifest file when using the new build system.
+    _ = XcodeBuild.run(arguments: xcodeBuildArguments + ["-dry-run"], inPath: path)
+
+    // Extract `PROJECT_TEMP_ROOT`
     fputs("Checking xcodebuild -showBuildSettings\n", stderr)
     guard let output = XcodeBuild.run(arguments: xcodeBuildArguments + ["-showBuildSettings"], inPath: path),
         let match = regexForProjectTempRoot.firstMatch(in: output, range: NSRange(output.startIndex..<output.endIndex, in: output)),
@@ -254,7 +257,8 @@ internal func checkNewBuildSystem(xcodeBuildArguments: [String],
         }.first.map { filter(arguments: $0) }
 
         if result != nil {
-            fputs("Assuming New Build System is used.\n", stderr)
+            fputs("Assuming New Build System is used.\nRunning xcodebuild\n", stderr)
+            _ = XcodeBuild.run(arguments: xcodeBuildArguments, inPath: path)
         }

[norio-nomura]

If we still need to build after -dry-run, I think that it is better to examine the manifest after building it normally. 🤔

[norio-nomura]

If we still need to build after -dry-run, I think that it is better to examine the manifest after building it normally. 🤔

As below without reverting 4f130be:

diff --git a/Source/SourceKittenFramework/Xcode.swift b/Source/SourceKittenFramework/Xcode.swift
index 78b22ac..b74090d 100644
--- a/Source/SourceKittenFramework/Xcode.swift
+++ b/Source/SourceKittenFramework/Xcode.swift
@@ -215,7 +215,11 @@ ${PROJECT_TEMP_ROOT}
 internal func checkNewBuildSystem(xcodeBuildArguments: [String],
                                   moduleName: String? = nil,
                                   inPath path: String) -> [String]? {
-    // Check `PROJECT_TEMP_ROOT`
+    // generates the manifest file when using the new build system.
+    fputs("Running xcodebuild\n", stderr)
+    _ = XcodeBuild.run(arguments: xcodeBuildArguments, inPath: path)
+
+    // Extract `PROJECT_TEMP_ROOT`
     fputs("Checking xcodebuild -showBuildSettings\n", stderr)
     guard let output = XcodeBuild.run(arguments: xcodeBuildArguments + ["-showBuildSettings"], inPath: path),
         let match = regexForProjectTempRoot.firstMatch(in: output, range: NSRange(output.startIndex..<output.endIndex, in: output)),

[jpsim]

Yes, you're totally right. 👍

[jpsim]

Can you get PROJECT_TEMP_ROOT from the xcodebuild log?

[norio-nomura]

The minimum xcodebuild log is as follows:

# Xcode 10
$ xcodebuild -workspace Carthage/Checkouts/Commandant/Commandant.xcworkspace/ -scheme Commandant build -verbose
note: Using new build system
note: Planning build
note: Constructing build description

** BUILD SUCCEEDED ** [0.731 sec]

# Xcode 9
$ DEVELOPER_DIR=/Applications/Xcode.app xcodebuild -workspace Carthage/Checkouts/Commandant/Commandant.xcworkspace/ -scheme Commandant build -verbose
=== BUILD TARGET Result-Mac OF PROJECT Result WITH CONFIGURATION Debug ===

Check dependencies

=== BUILD TARGET Commandant OF PROJECT Commandant WITH CONFIGURATION Debug ===

Check dependencies

** BUILD SUCCEEDED **

So using -showBuildSettings is required to getting PROJECT_TEMP_ROOT.

[norio-nomura]

Rewrote and rebased.

[jpsim]

Hmm, I think projects that don’t use the new build system will now be built twice 😬. It would still be worthwhile if most projects use the new build system.

What do you think?

[norio-nomura]

projects that don’t use the new build system will now be built twice

That will be the worst case. If the target module is not updated by the first build, second build with clean action will be required. In such case, I expect that the first build will be done in a short time.

[jpsim]

In such case, I expect that the first build will be done in a short time.

For CI jobs that run jazzy for example (which relies on this functionality), the first build will build from scratch, then the second clean build will also build from scratch, doubling the time spent building the project.

[norio-nomura]

In that case, it should return after the first build.

[norio-nomura]

In that case, it should return after the first build.

Sorry, I should mention that I also added parseCompilerArguments() to first build.

[jpsim]

Ah I missed that! Let me take another look.

[jpsim]

🎉

[norio-nomura]

Thanks! 🙏