Fix error handling for dump symbol graph

We were ignoring exit codes and output here, making the corresponding tests impossible to debug (and probably also making the command hard to use).

Author: neonichu

Sources/Commands/PackageTools/DumpCommands.swift

@@ -69,12 +69,22 @@ struct DumpSymbolGraph: SwiftCommand {
         let targets = try buildSystem.getPackageGraph().rootPackages.flatMap{ $0.targets }.filter{ $0.type == .library }
         for target in targets {
             print("-- Emitting symbol graph for", target.name)
-            try symbolGraphExtractor.extractSymbolGraph(
+            let result = try symbolGraphExtractor.extractSymbolGraph(
                 target: target,
                 buildPlan: buildPlan,
+                outputRedirection: .collect(redirectStderr: true),
                 outputDirectory: symbolGraphDirectory,
                 verboseOutput: swiftTool.logLevel <= .info
             )
+
+            if result.exitStatus != .terminated(code: 0) {
+                switch result.output {
+                case .success(let value):
+                    swiftTool.observabilityScope.emit(error: "Failed to emit symbol graph for '\(target.c99name)': \(String(decoding: value, as: UTF8.self))")
+                case .failure(let error):
+                    swiftTool.observabilityScope.emit(error: "Internal error while emitting symbol graph for '\(target.c99name)': \(error)")
+                }
+            }
         }
 
         print("Files written to", symbolGraphDirectory.pathString)

Sources/Commands/Utilities/SymbolGraphExtract.swift

@@ -23,6 +23,7 @@ import DriverSupport
 #endif
 
 import class TSCBasic.Process
+import struct TSCBasic.ProcessResult
 
 /// A wrapper for swift-symbolgraph-extract tool.
 public struct SymbolGraphExtract {
@@ -56,7 +57,7 @@ public struct SymbolGraphExtract {
         outputRedirection: TSCBasic.Process.OutputRedirection = .none,
         outputDirectory: AbsolutePath,
         verboseOutput: Bool
-    ) throws {
+    ) throws -> ProcessResult {
         let buildParameters = buildPlan.buildParameters
         try self.fileSystem.createDirectory(outputDirectory, recursive: true)
 
@@ -101,6 +102,6 @@ public struct SymbolGraphExtract {
             outputRedirection: outputRedirection
         )
         try process.launch()
-        try process.waitUntilExit()
+        return try process.waitUntilExit()
     }
 }

Tests/CommandsTests/PackageToolTests.swift

@@ -497,7 +497,7 @@ final class PackageToolTests: CommandsTestCase {
 
         let arguments = withPrettyPrinting ? ["dump-symbol-graph", "--pretty-print"] : ["dump-symbol-graph"]
 
-        _ = try SwiftPM.Package.execute(arguments, packagePath: path, env: ["SWIFT_SYMBOLGRAPH_EXTRACT": symbolGraphExtractorPath.pathString])
+        let result = try SwiftPM.Package.execute(arguments, packagePath: path, env: ["SWIFT_SYMBOLGRAPH_EXTRACT": symbolGraphExtractorPath.pathString])
         let enumerator = try XCTUnwrap(FileManager.default.enumerator(at: URL(fileURLWithPath: path.pathString), includingPropertiesForKeys: nil), file: file, line: line)
 
         var symbolGraphURL: URL?
@@ -506,7 +506,13 @@ final class PackageToolTests: CommandsTestCase {
             break
         }
 
-        let symbolGraphData = try Data(contentsOf: XCTUnwrap(symbolGraphURL, file: file, line: line))
+        let symbolGraphData: Data
+        if let symbolGraphURL {
+            symbolGraphData = try Data(contentsOf: symbolGraphURL)
+        } else {
+            XCTFail("Failed to extract symbol graph: \(result.stdout)\n\(result.stderr)")
+            return nil
+        }
 
         // Double check that it's a valid JSON
         XCTAssertNoThrow(try JSONSerialization.jsonObject(with: symbolGraphData), file: file, line: line)