[swift-stdlib-tool] Add support for back deployed concurrency

This tool was mostly already compatible with copying
`libswift_Concurrency.dylib` based on whether or not the executables it
was scanning linked it. The only thing missing was that it can now end
up copying from different source directories, the older `swift-5.0`
directory, and the new `swift-5.5` directory.

This change allows users to pass `--source-libraries` multiple times
(or picks a default with both) in order to have it scan both directories
for any libraries the app links. The biggest part of this change is
instead of storing just the library name throughout this logic we now
store the actual discovered path, so that we don't have to loop through
all potential source directories each time we need to find the library,
only the first time.

Author: keith

tools/swift-stdlib-tool/swift-stdlib-tool.mm

@@ -803,22 +803,22 @@ void copyAndStripBitcode(NSString *src, NSString *dst)
 }
 
 
-void copyLibraries(NSString *src_dir, NSString *dst_dir, 
+void copyLibraries(NSString *dst_dir,
                    NSMutableDictionary *libs, bool stripBitcode)
 {
     NSFileManager *fm = NSFileManager.defaultManager;
 
     [fm createDirectoryAtPath: dst_dir withIntermediateDirectories:YES 
      attributes:nil error:nil];
 
-    for (NSString *lib in libs) @autoreleasepool {
-        NSString *src = [src_dir stringByAppendingPathComponent:lib]; 
-        NSString *dst = [dst_dir stringByAppendingPathComponent:lib];
-        
+    for (NSString *src in libs) @autoreleasepool {
+        NSString *dst = [
+            dst_dir stringByAppendingPathComponent:src.lastPathComponent];
+
         // Compare UUIDs of src and dst and don't copy if they're the same.
         // Do not use mod times for this task: the dst copy gets code-signed 
         // and bitcode-stripped so it can look newer than it really is.
-        NSSet *srcUUIDs = libs[lib];
+        NSSet *srcUUIDs = libs[src];
         NSMutableSet *dstUUIDs = [NSMutableSet set];
         process(dst, nil, ^(NSUUID *uuid) {
             [dstUUIDs addObject:uuid];
@@ -831,15 +831,14 @@ void copyLibraries(NSString *src_dir, NSString *dst_dir,
 
         if ([srcUUIDs isEqualToSet:dstUUIDs]) {
             log_v("%s is up to date at %s", 
-                  lib.fileSystemRepresentation, dst.fileSystemRepresentation);
+                  src.fileSystemRepresentation, dst.fileSystemRepresentation);
             continue;
         }
 
         // Perform the copy.
-        
-        log_v("Copying %s from %s to %s", 
-              lib.fileSystemRepresentation, 
-              src_dir.fileSystemRepresentation, 
+
+        log_v("Copying %s to %s",
+              src.fileSystemRepresentation,
               dst_dir.fileSystemRepresentation);
 
         [fm removeItemAtPath:dst error:nil];  // fixme report this err?
@@ -899,7 +898,7 @@ int main(int argc, const char *argv[])
         // Copy source.
         // --source-libraries
         // or /path/to/swift-stdlib-tool/../../lib/swift/<--platform>
-        NSString *src_dir = nil;
+        NSMutableArray<NSString *> *src_dirs = [NSMutableArray array];
 
         // Copy destinations, signed and unsigned.
         // --destination and --unsigned-destination
@@ -939,7 +938,7 @@ int main(int argc, const char *argv[])
                 [embedDirs addObject:[NSString stringWithUTF8String:argv[++i]]];
             }
             if (0 == strcmp(argv[i], "--source-libraries")) {
-                src_dir = [NSString stringWithUTF8String:argv[++i]];
+                [src_dirs addObject:[NSString stringWithUTF8String:argv[++i]]];
             }
             if (0 == strcmp(argv[i], "--platform")) {
                 platform = [NSString stringWithUTF8String:argv[++i]];
@@ -976,22 +975,24 @@ int main(int argc, const char *argv[])
         }
 
         // Fix up src_dir and platform values.
-        if (!src_dir && !platform) {
-            // Neither src_dir nor platform is set. Die.
+        if (![src_dirs count] && !platform) {
+            // Neither src_dirs nor platform is set. Die.
             fail_usage("At least one of --source-libraries and --platform "
                        "must be set.");
         }
-        else if (!src_dir) {
-            // platform is set but src_dir is not. 
-            // Use platform to set src_dir relative to us.
-            src_dir = [[[self_executable stringByDeletingLastPathComponent]
-                        stringByDeletingLastPathComponent]
-                       sst_stringByAppendingPathComponents:
-                       @[ @"lib", @"swift-5.0", platform ]];
+        else if (![src_dirs count]) {
+            // platform is set but src_dirs is not.
+            // Use platform to set src_dirs relative to us.
+            NSString *root_path = [[self_executable stringByDeletingLastPathComponent]
+                                    stringByDeletingLastPathComponent];
+            src_dirs = [@[
+                [root_path sst_stringByAppendingPathComponents: @[ @"lib", @"swift-5.0", platform ]],
+                [root_path sst_stringByAppendingPathComponents: @[ @"lib", @"swift-5.5", platform ]],
+            ] mutableCopy];
         } else if (!platform) {
-            // src_dir is set but platform is not. 
-            // Pick platform from src_dir's name.
-            platform = src_dir.lastPathComponent;
+            // src_dirs is set but platform is not.
+            // Pick platform from any src_dirs' name.
+            platform = src_dirs[0].lastPathComponent;
         }
 
         // Add the platform to unsigned_dst_dir if it is not already present.
@@ -1037,10 +1038,13 @@ int main(int argc, const char *argv[])
             process(path, 
                ^(NSString *linkedLib) { 
                     @autoreleasepool {
-                        NSString *linkedSrc =
-                            [src_dir stringByAppendingPathComponent:linkedLib];
-                        if ([fm fileExistsAtPath:linkedSrc]) {
-                            swiftLibs[linkedLib] = [NSMutableSet set]; 
+                        for (NSString *src_dir in src_dirs) {
+                            NSString *linkedSrc =
+                                [src_dir stringByAppendingPathComponent:linkedLib];
+                            if ([fm fileExistsAtPath:linkedSrc]) {
+                                swiftLibs[linkedSrc] = [NSMutableSet set];
+                                break;
+                            }
                         }
                     }
                 }, 
@@ -1051,24 +1055,26 @@ int main(int argc, const char *argv[])
         // Also collect the Swift libraries' UUIDs.
         NSMutableArray *worklist = [swiftLibs.allKeys mutableCopy];
         while (worklist.count) @autoreleasepool {
-            NSString *lib = [worklist lastObject];
+            NSString *path = [worklist lastObject];
             [worklist removeLastObject];
-            NSString *path = [src_dir stringByAppendingPathComponent:lib];
             process(path, 
                 ^(NSString *linkedLib) {
                     @autoreleasepool {
-                        NSString *linkedSrc = 
-                            [src_dir stringByAppendingPathComponent:linkedLib];
-                        if (!swiftLibs[linkedLib]  &&  
-                            [fm fileExistsAtPath:linkedSrc]) 
-                        {
-                            swiftLibs[linkedLib] = [NSMutableSet set];
-                            [worklist addObject:linkedLib];
+                        for (NSString *src_dir in src_dirs) {
+                            NSString *linkedSrc =
+                                [src_dir stringByAppendingPathComponent:linkedLib];
+                            if (!swiftLibs[linkedSrc] &&
+                                [fm fileExistsAtPath:linkedSrc])
+                            {
+                                swiftLibs[linkedSrc] = [NSMutableSet set];
+                                [worklist addObject:linkedSrc];
+                                break;
+                            }
                         }
                     }
                 }, 
                 ^(NSUUID *uuid) {
-                    NSMutableSet *uuids = swiftLibs[lib];
+                    NSMutableSet *uuids = swiftLibs[path];
                     [uuids addObject:uuid];
                 });
         }
@@ -1078,31 +1084,36 @@ int main(int argc, const char *argv[])
         // with --resource-library.
         NSMutableDictionary *swiftLibsForResources = [NSMutableDictionary new];
         for (NSString *lib in resourceLibraries) @autoreleasepool {
-            NSString *libSrc = [src_dir stringByAppendingPathComponent:lib];
-            if ([fm fileExistsAtPath:libSrc]) {
-                swiftLibsForResources[lib] = [NSMutableSet set];
+            for (NSString *src_dir in src_dirs) {
+                NSString *libSrc = [src_dir stringByAppendingPathComponent:lib];
+                if ([fm fileExistsAtPath:libSrc]) {
+                    swiftLibsForResources[libSrc] = [NSMutableSet set];
+                    break;
+                }
             }
         }
 
         // Collect dependencies of --resource-library libs.
         worklist = [swiftLibsForResources.allKeys mutableCopy];
         while (worklist.count) @autoreleasepool {
-            NSString *lib = [worklist lastObject];
+            NSString *path = [worklist lastObject];
             [worklist removeLastObject];
-            NSString *path = [src_dir stringByAppendingPathComponent:lib];
             process(path,
                 ^(NSString *linkedLib) {
-                    NSString *linkedSrc =
-                        [src_dir stringByAppendingPathComponent:linkedLib];
-                    if (!swiftLibsForResources[linkedLib] &&
-                        [fm fileExistsAtPath:linkedSrc])
-                    {
-                        swiftLibsForResources[linkedLib] = [NSMutableSet set];
-                        [worklist addObject:linkedLib];
+                    for (NSString *src_dir in src_dirs) {
+                        NSString *linkedSrc =
+                            [src_dir stringByAppendingPathComponent:linkedLib];
+                        if (!swiftLibsForResources[linkedSrc] &&
+                            [fm fileExistsAtPath:linkedSrc])
+                        {
+                            swiftLibsForResources[linkedSrc] = [NSMutableSet set];
+                            [worklist addObject:linkedSrc];
+                            break;
+                        }
                     }
                 },
                 ^(NSUUID *uuid) {
-                    NSMutableSet *uuids = swiftLibsForResources[lib];
+                    NSMutableSet *uuids = swiftLibsForResources[path];
                     [uuids addObject:uuid];
                 });
         }
@@ -1111,26 +1122,25 @@ int main(int argc, const char *argv[])
         // Print the Swift libraries (full path to toolchain's copy)
         if (print) {
             for (NSString *lib in swiftLibs) {
-                printf("%s\n", [[src_dir stringByAppendingPathComponent:lib] 
-                                fileSystemRepresentation]);
+                printf("%s\n", lib.fileSystemRepresentation);
             }
         }
 
         // Copy the Swift libraries to $build_dir/$frameworks
         // and $build_dir/$unsigned_frameworks
         if (copy) {
-            copyLibraries(src_dir, dst_dir, swiftLibs, stripBitcode);
+            copyLibraries(dst_dir, swiftLibs, stripBitcode);
             if (unsigned_dst_dir) {
                 // Never strip bitcode from the unsigned libraries. 
                 // Their existing signatures must be preserved.
-                copyLibraries(src_dir, unsigned_dst_dir, swiftLibs, false);
+                copyLibraries(unsigned_dst_dir, swiftLibs, false);
             }
 
             if (resource_dst_dir) {
                 // Never strip bitcode from resources libraries, for
                 // the same reason as the libraries copied to
                 // unsigned_dst_dir.
-                copyLibraries(src_dir, resource_dst_dir, swiftLibsForResources, false);
+                copyLibraries(resource_dst_dir, swiftLibsForResources, false);
             }
         }