Fix swift-symbolgraph-extract search paths

Fixes and architecture and implementation bug where the include paths
for swift symbolgraph extract were being determined inside build plan
instead of by the target build description. This bug resulted in the
wrong set of paths being determined.

The new code moves the path determination logic into the proper target
build descriptions and releverages the already computed include paths.
The result of this is symbol graphs can be generated for Swift and C
targets properly now without duplicate module in the search paths and
with correct `-fmodule` usage.

Author: rauhul

Sources/Build/BuildDescription/ClangTargetBuildDescription.swift

@@ -211,13 +211,17 @@ public final class ClangTargetBuildDescription {
     /// this module.
     public func symbolGraphExtractArguments() throws -> [String] {
         var args = [String]()
-
         if self.clangTarget.isCXX {
             args += ["-cxx-interoperability-mode=default"]
         }
         if let cxxLanguageStandard = self.clangTarget.cxxLanguageStandard {
             args += ["-Xcc", "-std=\(cxxLanguageStandard)"]
         }
+        args += ["-I", self.clangTarget.includeDir.pathString]
+        args += self.additionalFlags
+        // Unconditionally use clang modules with swift tools.
+        args += try self.clangModuleArguments().asSwiftcCCompilerFlags()
+        args += try self.currentModuleMapFileArguments().asSwiftcCCompilerFlags()
         return args
     }
 
@@ -253,7 +257,6 @@ public final class ClangTargetBuildDescription {
             args += self.buildParameters.indexStoreArguments(for: target)
         }
 
-        // Enable Clang module flags, if appropriate.
         let triple = self.buildParameters.triple
         // Swift is able to use modules on non-Darwin platforms because it injects its own module maps
         // via vfs. However, nothing does that for C based compilation, and so non-Darwin platforms can't
@@ -263,7 +266,7 @@ public final class ClangTargetBuildDescription {
         // clang modules aren't fully supported in C++ mode in the current Darwin SDKs.
         let enableModules = triple.isDarwin() && !isCXX
         if enableModules {
-            args += ["-fmodules", "-fmodule-name=" + target.c99name]
+            args += try self.clangModuleArguments()
         }
 
         // Only add the build path to the framework search path if there are binary frameworks to link against.
@@ -273,9 +276,7 @@ public final class ClangTargetBuildDescription {
 
         args += ["-I", clangTarget.includeDir.pathString]
         args += additionalFlags
-        if enableModules {
-            args += try moduleCacheArgs
-        }
+
         args += buildParameters.sanitizers.compileCFlags()
 
         // Add arguments from declared build settings.
@@ -433,11 +434,22 @@ public final class ClangTargetBuildDescription {
         return compilationConditions
     }
 
-    /// Module cache arguments.
-    private var moduleCacheArgs: [String] {
-        get throws {
-            try ["-fmodules-cache-path=\(buildParameters.moduleCache.pathString)"]
+    /// Enable Clang module flags.
+    private func clangModuleArguments() throws -> [String] {
+        let cachePath = try self.buildParameters.moduleCache.pathString
+        return [
+            "-fmodules",
+            "-fmodule-name=\(self.target.c99name)",
+            "-fmodules-cache-path=\(cachePath)",
+        ]
+    }
+    
+    private func currentModuleMapFileArguments() throws -> [String] {
+        // Pass the path to the current module's module map if present.
+        if let moduleMap = self.moduleMap {
+            return ["-fmodule-map-file=\(moduleMap.pathString)"]
         }
+        return []
     }
 
     /// Generate the resource bundle accessor, if appropriate.

Sources/Build/BuildDescription/SwiftTargetBuildDescription.swift

@@ -633,6 +633,7 @@ public final class SwiftTargetBuildDescription {
         var args = [String]()
         args += try self.cxxInteroperabilityModeArguments(
             propagateFromCurrentModuleOtherSwiftFlags: true)
+        args += try self.createAPIToolCommonArgs(includeLibrarySearchPaths: true)
         return args
     }
 

Sources/Build/BuildPlan/BuildPlan.swift

@@ -648,6 +648,8 @@ public class BuildPlan: SPMBuildCore.BuildPlan {
         }
     }
 
+    /// Determines the arguments needed to run `swift-symbolgraph-extract` for
+    /// a particular module.
     public func symbolGraphExtractArguments(for module: ResolvedModule) throws -> [String] {
         guard let description = self.targetMap[module.id] else {
             throw InternalError("Expected description for module \(module)")

Sources/Commands/Utilities/SymbolGraphExtract.swift

@@ -70,7 +70,6 @@ public struct SymbolGraphExtract {
         // FIXME: everything here should be in symbolGraphExtractArguments
         commandLine += ["-module-name", module.c99name]
         commandLine += try buildParameters.tripleArgs(for: module)
-        commandLine += try buildPlan.createAPIToolCommonArgs(includeLibrarySearchPaths: true)
         commandLine += ["-module-cache-path", try buildParameters.moduleCache.pathString]
         if verboseOutput {
             commandLine += ["-v"]

Sources/SPMBuildCore/BuildSystem/BuildSystem.swift

@@ -91,6 +91,8 @@ public protocol BuildPlan {
     func createAPIToolCommonArgs(includeLibrarySearchPaths: Bool) throws -> [String]
     func createREPLArguments() throws -> [String]
 
+    /// Determines the arguments needed to run `swift-symbolgraph-extract` for
+    /// a particular module.
     func symbolGraphExtractArguments(for module: ResolvedModule) throws -> [String]
 }
 

Tests/BuildTests/BuildPlanTests.swift

@@ -1410,13 +1410,13 @@ final class BuildPlanTests: XCTestCase {
         args += ["-O0", "-DSWIFT_PACKAGE=1", "-DDEBUG=1"]
         args += ["-fblocks"]
         #if os(macOS) // FIXME(5473) - support modules on non-Apple platforms
-        args += ["-fmodules", "-fmodule-name=extlib"]
+        args += [
+            "-fmodules",
+            "-fmodule-name=extlib",
+            "-fmodules-cache-path=\(buildPath.appending(components: "ModuleCache"))",
+        ]
         #endif
         args += ["-I", ExtPkg.appending(components: "Sources", "extlib", "include").pathString]
-        #if os(macOS) // FIXME(5473) - support modules on non-Apple platforms
-        args += ["-fmodules-cache-path=\(buildPath.appending(components: "ModuleCache"))"]
-        #endif
-
         args += [hostTriple.isWindows() ? "-gdwarf" : "-g"]
 
         if hostTriple.isLinux() {
@@ -1439,7 +1439,11 @@ final class BuildPlanTests: XCTestCase {
         args += ["-O0", "-DSWIFT_PACKAGE=1", "-DDEBUG=1"]
         args += ["-fblocks"]
         #if os(macOS) // FIXME(5473) - support modules on non-Apple platforms
-        args += ["-fmodules", "-fmodule-name=exe"]
+        args += [
+            "-fmodules",
+            "-fmodule-name=exe",
+            "-fmodules-cache-path=\(buildPath.appending(components: "ModuleCache"))",
+        ]
         #endif
         args += [
             "-I", Pkg.appending(components: "Sources", "exe", "include").pathString,
@@ -1448,9 +1452,6 @@ final class BuildPlanTests: XCTestCase {
             "-I", ExtPkg.appending(components: "Sources", "extlib", "include").pathString,
             "-fmodule-map-file=\(buildPath.appending(components: "extlib.build", "module.modulemap"))",
         ]
-        #if os(macOS) // FIXME(5473) - support modules on non-Apple platforms
-        args += ["-fmodules-cache-path=\(buildPath.appending(components: "ModuleCache"))"]
-        #endif
         args += [hostTriple.isWindows() ? "-gdwarf" : "-g"]
 
         if hostTriple.isLinux() {
@@ -1796,12 +1797,13 @@ final class BuildPlanTests: XCTestCase {
         args += ["-O0", "-DSWIFT_PACKAGE=1", "-DDEBUG=1"]
         args += ["-fblocks"]
         #if os(macOS) // FIXME(5473) - support modules on non-Apple platforms
-        args += ["-fmodules", "-fmodule-name=lib"]
+        args += [
+            "-fmodules",
+            "-fmodule-name=lib",
+            "-fmodules-cache-path=\(buildPath.appending(components: "ModuleCache"))",
+        ]
         #endif
         args += ["-I", Pkg.appending(components: "Sources", "lib", "include").pathString]
-        #if os(macOS) // FIXME(5473) - support modules on non-Apple platforms
-        args += ["-fmodules-cache-path=\(buildPath.appending(components: "ModuleCache"))"]
-        #endif
         args += [hostTriple.isWindows() ? "-gdwarf" : "-g"]
 
         if hostTriple.isLinux() {
@@ -3035,12 +3037,13 @@ final class BuildPlanTests: XCTestCase {
         expectedExeBasicArgs += ["-target", defaultTargetTriple]
         expectedExeBasicArgs += ["-O0", "-DSWIFT_PACKAGE=1", "-DDEBUG=1", "-fblocks"]
         #if os(macOS) // FIXME(5473) - support modules on non-Apple platforms
-        expectedExeBasicArgs += ["-fmodules", "-fmodule-name=exe"]
+        expectedExeBasicArgs += [
+            "-fmodules",
+            "-fmodule-name=exe",
+            "-fmodules-cache-path=\(buildPath.appending(components: "ModuleCache"))"
+        ]
         #endif
         expectedExeBasicArgs += ["-I", Pkg.appending(components: "Sources", "exe", "include").pathString]
-        #if os(macOS) // FIXME(5473) - support modules on non-Apple platforms
-        expectedExeBasicArgs += ["-fmodules-cache-path=\(buildPath.appending(components: "ModuleCache"))"]
-        #endif
 
         expectedExeBasicArgs += [triple.isWindows() ? "-gdwarf" : "-g"]