Auto generate module map file for C libs

Author: aciidgh

Fixtures/ClangModules/CLibraryFlat/include/module.modulemap

@@ -0,0 +1,7 @@
+import PackageDescription
+
+let package = Package(
+    name: "ModuleMapGenerationCases",
+    targets: [
+		Target(name: "Baz", dependencies: ["Foo", "Bar", "Jaz"])]
+)

Fixtures/ClangModules/CLibrarySources/Sources/include/module.modulemap

@@ -0,0 +1,8 @@
+#include "include/Bar.h"
+
+int bar() {
+    int a = 6;
+    int b = a;
+    a = b;
+    return a;
+}

Fixtures/ClangModules/CLibraryiquote/Sources/Bar/include/module.modulemap

@@ -0,0 +1 @@
+int bar();

Fixtures/ClangModules/CLibraryiquote/Sources/Foo/include/module.modulemap

@@ -0,0 +1,7 @@
+import Foo
+import Bar
+import Jaz
+
+let _ = foo()
+let _ = bar()
+let _ = jaz()

Fixtures/ClangModules/ModuleMapGenerationCases/Package.swift

@@ -0,0 +1,8 @@
+#include "include/Foo/Foo.h"
+
+int foo() {
+    int a = 5;
+    int b = a;
+    a = b;
+    return a;
+}

Fixtures/ClangModules/ModuleMapGenerationCases/Sources/Bar/Bar.c

@@ -0,0 +1 @@
+int foo();

Fixtures/ClangModules/ModuleMapGenerationCases/Sources/Bar/include/Bar.h

@@ -0,0 +1,8 @@
+#include "include/Jaz/Paz.h"
+
+int jaz() {
+    int a = 6;
+    int b = a;
+    a = b;
+    return a;
+}

Fixtures/ClangModules/ModuleMapGenerationCases/Sources/Baz/main.swift

@@ -0,0 +1 @@
+int jaz();

Fixtures/ClangModules/ModuleMapGenerationCases/Sources/Foo/Foo.c

@@ -0,0 +1,7 @@
+
+int noDir() {
+    int a = 6;
+    int b = a;
+    a = b;
+    return a;
+}

Fixtures/ClangModules/ModuleMapGenerationCases/Sources/Foo/include/Foo/Foo.h

@@ -40,16 +40,10 @@ public func describe(prefix: String, _ conf: Configuration, _ modules: [Module],
             targets.append(compile, for: module)
 
         case let module as ClangModule:
-            //FIXME: Generate modulemaps if possible
-            //Since we're not generating modulemaps currently we'll just emit empty module map file
-            //if it not present
-            if module.type == .Library && !module.moduleMapPath.isFile {
-                try POSIX.mkdir(module.moduleMapPath.parentDirectory)
-                try fopen(module.moduleMapPath, mode: .Write) { fp in
-                    try fputs("\n", fp)
-                }
+            if module.type == .Library {
+                try module.generateModuleMap()
             }
-
+            
             let (compile, mkdir) = Command.compile(clangModule: module, externalModules: externalModules, configuration: conf, prefix: prefix)
             commands.append(compile)
             commands.append(mkdir)

Fixtures/ClangModules/ModuleMapGenerationCases/Sources/Jaz/Jaz.c

@@ -9,6 +9,9 @@
 */
 
 import func POSIX.getenv
+import func POSIX.mkdir
+import func POSIX.fopen
+import func libc.fclose
 import PackageType
 import Utility
 
@@ -32,6 +35,83 @@ extension CModule {
     }
 }
 
+extension ClangModule {
+    
+    public enum ModuleMapError: ErrorProtocol {
+        case UnsupportedIncludeLayoutForModule(String)
+    }
+    
+    public func generateModuleMap() throws {
+        
+        //Return if module map is already present
+        guard !moduleMapPath.isFile else {
+            return
+        }
+        
+        let includeDir = path
+        
+        //Generate empty module map if include dir is not present
+        guard includeDir.isDirectory else {
+            print("warning: No include directory, generating empty module map")
+            try POSIX.mkdir(includeDir)
+            try fopen(moduleMapPath, mode: .Write) { fp in
+                try fputs("\n", fp)
+            }
+            return
+        }
+        
+        let walked = walk(includeDir, recursively: false).map{$0}
+        
+        let files = walked.filter{$0.isFile && $0.hasSuffix(".h")}
+        let dirs = walked.filter{$0.isDirectory}
+        
+        if dirs.isEmpty {
+            guard !files.isEmpty else { throw ModuleMapError.UnsupportedIncludeLayoutForModule(name) }
+            try createModuleMap(.FlatHeaderLayout)
+            return
+        }
+        
+        guard let moduleHeaderDir = dirs.first where moduleHeaderDir.basename == name && files.isEmpty else {
+            throw ModuleMapError.UnsupportedIncludeLayoutForModule(name)
+        }
+        
+        let umbrellaHeader = Path.join(moduleHeaderDir, "\(name).h")
+        if umbrellaHeader.isFile {
+            try createModuleMap(.HeaderFile)
+        } else {
+            try createModuleMap(.ModuleNameDir)
+        }
+    }
+    
+    private enum UmbrellaType {
+        case FlatHeaderLayout
+        case ModuleNameDir
+        case HeaderFile
+    }
+    
+    private func createModuleMap(type: UmbrellaType) throws {
+        let moduleMap = try fopen(moduleMapPath, mode: .Write)
+        defer { fclose(moduleMap) }
+        
+        try fputs("module \(name) {\n", moduleMap)
+        try fputs("    umbrella ", moduleMap)
+        
+        switch type {
+        case .FlatHeaderLayout:
+            try fputs("\".\"\n", moduleMap)
+        case .ModuleNameDir:
+            try fputs("\"\(name)\"\n", moduleMap)
+        case .HeaderFile:
+            try fputs("header \"\(name)/\(name).h\"\n", moduleMap)
+            
+        }
+        
+        try fputs("    link \"\(name)\"\n", moduleMap)
+        try fputs("    export *\n", moduleMap)
+        try fputs("}\n", moduleMap)
+    }
+}
+
 extension Product {
     var Info: (_: Void, plist: String) {
         let bundleExecutable = "Package"

Fixtures/ClangModules/ModuleMapGenerationCases/Sources/Jaz/include/Jaz/Paz.h

@@ -93,7 +93,6 @@ public class ClangModule: CModule {
 
     public init(name: String, sources: Sources) {
         self.sources = sources
-        //TODO: generate module map using swiftpm if layout can support
         super.init(name: name, path: sources.root + "/include")
     }
 }

Fixtures/ClangModules/ModuleMapGenerationCases/Sources/NoIncludeDir/Jaz.c

@@ -73,7 +73,7 @@ class TestClangModulesTestCase: XCTestCase {
             XCTAssertEqual(output, "hello 5")
         }
     }
-
+    
     func testCUsingCDep2() {
         //The C dependency "Foo" has different layout
         fixture(name: "DependencyResolution/External/CUsingCDep2") { prefix in
@@ -82,6 +82,17 @@ class TestClangModulesTestCase: XCTestCase {
             XCTAssertDirectoryExists(prefix, "Bar/Packages/Foo-1.2.3")
         }
     }
+    
+    func testModuleMapGenerationCases() {
+        fixture(name: "ClangModules/ModuleMapGenerationCases") { prefix in
+            XCTAssertBuilds(prefix)
+            XCTAssertFileExists(prefix, ".build", "debug", "libFoo.so")
+            XCTAssertFileExists(prefix, ".build", "debug", "libBar.so")
+            XCTAssertFileExists(prefix, ".build", "debug", "libJaz.so")
+            XCTAssertFileExists(prefix, ".build", "debug", "libNoIncludeDir.so")
+            XCTAssertFileExists(prefix, ".build", "debug", "Baz")
+        }
+    }
 }
 
 
@@ -95,6 +106,7 @@ extension TestClangModulesTestCase {
             ("testiquoteDep", testiquoteDep),
             ("testCUsingCDep", testCUsingCDep),
             ("testCExecutable", testCExecutable),
+            ("testModuleMapGenerationCases", testModuleMapGenerationCases),
         ]
     }
 }