Made the build script report failed builds through its exit code (#1067)

app/Build/Commands/UpdateMetadataCommands.cs

@@ -2,6 +2,8 @@ using System.Diagnostics;
 using System.Globalization;
 using System.Text.RegularExpressions;
 
+using Build.Tools;
+
 using SharedTools;
 
 namespace Build.Commands;
@@ -20,26 +22,27 @@ public sealed partial class UpdateMetadataCommands
         [Option("offline", Description = "Skip downloads and use locally available build dependencies")] bool offline = false)
     {
         if(!Environment.IsWorkingDirectoryValid())
-            return;
+            throw new CommandExitedException(1);
 
         // Validate parameters: either action or version must be specified, but not both:
         if (action == PrepareAction.NONE && string.IsNullOrWhiteSpace(version))
         {
             Console.WriteLine("- Error: You must specify either --action (-a) or --version (-v).");
-            return;
+            throw new CommandExitedException(1);
         }
 
         if (action != PrepareAction.NONE && !string.IsNullOrWhiteSpace(version))
         {
             Console.WriteLine("- Error: You cannot specify both --action and --version. Please use only one.");
-            return;
+            throw new CommandExitedException(1);
         }
 
         // If version is specified, use SET action:
         if (!string.IsNullOrWhiteSpace(version))
             action = PrepareAction.SET;
 
-        // Prepare the metadata for the next release:
+        // Prepare the metadata for the next release. When this fails, it ends the
+        // whole command, so that nothing is built from half-prepared metadata:
         await this.PerformPrepare(action, true, version);
 
         await this.BuildPreparedRelease(offline);
@@ -50,7 +53,7 @@ public sealed partial class UpdateMetadataCommands
         [Option("offline", Description = "Skip downloads and use locally available build dependencies")] bool offline = false)
     {
         if(!Environment.IsWorkingDirectoryValid())
-            return;
+            throw new CommandExitedException(1);
 
         Console.WriteLine("==============================");
         Console.WriteLine("- Prepare a new build of the current release ...");
@@ -63,7 +66,7 @@ public sealed partial class UpdateMetadataCommands
         catch (InvalidOperationException exception)
         {
             Console.WriteLine($"- Error: {exception.Message}");
-            return;
+            throw new CommandExitedException(1);
         }
 
         await this.ApplyRebuildReleaseState(releaseState, DateTime.UtcNow);
@@ -76,7 +79,8 @@ public sealed partial class UpdateMetadataCommands
     private async Task BuildPreparedRelease(bool offline)
     {
         // Build once to allow the Rust compiler to read the changed metadata
-        // and to update all .NET artifacts:
+        // and to update all .NET artifacts. When this build fails, it ends the
+        // whole command; nothing below runs on top of its broken artifacts:
         await this.Build(offline);
         
         // Now, we update the web assets (which may were updated by the first build):
@@ -187,18 +191,20 @@ public sealed partial class UpdateMetadataCommands
 
         Console.WriteLine("- Prepare the metadata for the next release ...");
 
-        var appVersion = await this.UpdateAppVersion(action, version);
+        var appVersion = await this.DetermineNextAppVersion(action, version);
         if (!string.IsNullOrWhiteSpace(appVersion.VersionText))
         {
             // The changelog is the source for the AppStream description. Check it before we write
-            // any further metadata, so that a missing changelog cannot leave a half-prepared release:
+            // any metadata, the version included, so that a missing changelog cannot leave a
+            // half-prepared release:
             var changelogPath = GetChangelogPath(appVersion.VersionText);
             if (!File.Exists(changelogPath))
             {
                 Console.WriteLine($"- Error: The changelog file '{Path.GetFileName(changelogPath)}' does not exist.");
-                return;
+                throw new CommandExitedException(1);
             }
 
+            await this.UpdateAppVersion(appVersion);
             var buildNumber = await this.IncreaseBuildNumber();
             var buildTime = await this.UpdateBuildTime();
             await this.UpdateChangelog(buildNumber, appVersion.VersionText, buildTime);
@@ -227,7 +233,7 @@ public sealed partial class UpdateMetadataCommands
         [Option("skip-verify", Description = "Skip the quality gate which otherwise runs before anything is built")] bool skipVerify = false)
     {
         if(!Environment.IsWorkingDirectoryValid())
-            return;
+            throw new CommandExitedException(1);
 
         //
         // The gate runs before anything is built, and the build stops when it does not pass. That
@@ -255,7 +261,7 @@ public sealed partial class UpdateMetadataCommands
         Console.Write($"- Start .NET build for {rid.ToUserFriendlyName()} ...");
         await this.ReadCommandOutput(pathApp, "dotnet", $"clean --configuration release --runtime {rid.AsMicrosoftRid()}");
         var dotnetBuildOutput = await this.ReadCommandOutput(pathApp, "dotnet", $"publish --configuration release --runtime {rid.AsMicrosoftRid()} --disable-build-servers --force");
-        var dotnetBuildOutputLines = dotnetBuildOutput.Split([global::System.Environment.NewLine], StringSplitOptions.RemoveEmptyEntries);
+        var dotnetBuildOutputLines = dotnetBuildOutput.Text.Split([global::System.Environment.NewLine], StringSplitOptions.RemoveEmptyEntries);
         var foundIssue = false;
         foreach (var buildOutputLine in dotnetBuildOutputLines)
         {
@@ -275,10 +281,23 @@ public sealed partial class UpdateMetadataCommands
         
         if(foundIssue)
             Console.WriteLine();
-        else
+        else if(dotnetBuildOutput.ExitCode is 0)
         {
             Console.WriteLine(" completed successfully.");
         }
+        else
+        {
+            // Unlike the Rust build, this one ran silently. When none of its lines looks like a
+            // diagnostic, its whole output is the only thing left to go on:
+            Console.WriteLine(" failed:");
+            Console.WriteLine(dotnetBuildOutput.Text);
+        }
+
+        if(dotnetBuildOutput.ExitCode is not 0)
+        {
+            Console.WriteLine($"- Error: The .NET build failed with exit code {dotnetBuildOutput.ExitCode}.");
+            throw new CommandExitedException(1);
+        }
 
         //
         // Prepare the .NET artifact to be used by Tauri as sidecar:
@@ -301,7 +320,7 @@ public sealed partial class UpdateMetadataCommands
         if (string.IsNullOrWhiteSpace(tauriSidecarArtifactName))
         {
             Console.WriteLine($"- Error: Unsupported rid '{rid.AsMicrosoftRid()}'.");
-            return;
+            throw new CommandExitedException(1);
         }
     
         var dotnetArtifactPath = Path.Combine(pathApp, "bin", "dist");
@@ -322,7 +341,7 @@ public sealed partial class UpdateMetadataCommands
         else
         {
             Console.WriteLine($"- Error: Published .NET artifact not found: '{dotnetPublishedPath}'.");
-            return;
+            throw new CommandExitedException(1);
         }
 
         Console.Write($"- Move the .NET artifact to the Tauri sidecar destination ...");
@@ -333,8 +352,11 @@ public sealed partial class UpdateMetadataCommands
         }
         catch (Exception e)
         {
+            // Building on would not fail: Tauri would quietly take whichever sidecar an earlier build
+            // left in its place, and the result would contain an outdated .NET app:
             Console.WriteLine(" failed.");
             Console.WriteLine($"   - Error: {e.Message}");
+            throw new CommandExitedException(1);
         }
         
         //
@@ -344,7 +366,7 @@ public sealed partial class UpdateMetadataCommands
         
         var pathRuntime = Environment.GetRustRuntimeDirectory();
         var rustBuildOutput = await this.ReadCommandOutput(pathRuntime, "cargo", "tauri build --no-bundle", true);
-        var rustBuildOutputLines = rustBuildOutput.Split([global::System.Environment.NewLine], StringSplitOptions.RemoveEmptyEntries);
+        var rustBuildOutputLines = rustBuildOutput.Text.Split([global::System.Environment.NewLine], StringSplitOptions.RemoveEmptyEntries);
         var foundRustIssue = false;
         foreach (var buildOutputLine in rustBuildOutputLines)
         {
@@ -362,11 +384,15 @@ public sealed partial class UpdateMetadataCommands
             }
         }
         
-        if(foundRustIssue)
         Console.WriteLine();
-        else
+        if(rustBuildOutput.ExitCode is not 0)
+        {
+            Console.WriteLine($"- Error: The Rust build failed with exit code {rustBuildOutput.ExitCode}.");
+            throw new CommandExitedException(1);
+        }
+
+        if(!foundRustIssue)
         {
-            Console.WriteLine();
             Console.WriteLine("- Compilation completed successfully.");
             Console.WriteLine();
         }
@@ -555,7 +581,7 @@ public sealed partial class UpdateMetadataCommands
         if (!ReleasesStartRegex().IsMatch(await File.ReadAllTextAsync(metainfoPath, Encoding.UTF8)))
             throw new InvalidOperationException("The AppStream metainfo does not contain a <releases> element.");
 
-        var headCommitHash = (await this.ReadCommandOutput(Environment.GetAIStudioDirectory(), "git", "rev-parse HEAD")).Trim();
+        var headCommitHash = (await this.ReadCommandOutput(Environment.GetAIStudioDirectory(), "git", "rev-parse HEAD")).Text.Trim();
         if (!GitCommitHashRegex().IsMatch(headCommitHash))
             throw new InvalidOperationException("The current Git commit hash could not be determined.");
 
@@ -850,7 +876,7 @@ public sealed partial class UpdateMetadataCommands
         var pathMetadata = Environment.GetMetadataPath();
         var lines = await File.ReadAllLinesAsync(pathMetadata, Encoding.UTF8);
         var currentCommitHash = lines[COMMIT_HASH_INDEX].Trim();
-        var headCommitHash = await this.ReadCommandOutput(Environment.GetAIStudioDirectory(), "git", "rev-parse HEAD");
+        var headCommitHash = (await this.ReadCommandOutput(Environment.GetAIStudioDirectory(), "git", "rev-parse HEAD")).Text;
         var first10Chars = headCommitHash[..11];
         var updatedCommitHash = $"{first10Chars}, release";
 
@@ -860,7 +886,7 @@ public sealed partial class UpdateMetadataCommands
         await WriteMetadataLinesAsync(pathMetadata, lines);
     }
 
-    private async Task<AppVersion> UpdateAppVersion(PrepareAction action, string? version = null)
+    private async Task<AppVersion> DetermineNextAppVersion(PrepareAction action, string? version = null)
     {
         const int APP_VERSION_INDEX = 0;
 
@@ -882,7 +908,7 @@ public sealed partial class UpdateMetadataCommands
             if (!versionMatch.Success)
             {
                 Console.WriteLine($"- Error: Invalid version format '{version}'. Expected format: major.minor.patch (e.g., 26.1.2)");
-                return new(string.Empty, 0, 0, 0);
+                throw new CommandExitedException(1);
             }
 
             newMajor = int.Parse(versionMatch.Groups["major"].Value);
@@ -916,13 +942,19 @@ public sealed partial class UpdateMetadataCommands
             }
         }
 
-        var updatedAppVersion = $"{newMajor}.{newMinor}.{newPatch}";
+        return new($"{newMajor}.{newMinor}.{newPatch}", newMajor, newMinor, newPatch);
-        Console.WriteLine($"- Updating app version from '{currentAppVersionLine}' to '{updatedAppVersion}'.");
+    }
 
-        lines[APP_VERSION_INDEX] = updatedAppVersion;
+    private async Task UpdateAppVersion(AppVersion appVersion)
+    {
+        const int APP_VERSION_INDEX = 0;
+
+        var pathMetadata = Environment.GetMetadataPath();
+        var lines = await File.ReadAllLinesAsync(pathMetadata, Encoding.UTF8);
+        Console.WriteLine($"- Updating app version from '{lines[APP_VERSION_INDEX].Trim()}' to '{appVersion.VersionText}'.");
+
+        lines[APP_VERSION_INDEX] = appVersion.VersionText;
         await WriteMetadataLinesAsync(pathMetadata, lines);
-
-        return new(updatedAppVersion, newMajor, newMinor, newPatch);
     }
 
     private async Task UpdateLicenceYear(string licenceFilePath)
@@ -1116,7 +1148,7 @@ public sealed partial class UpdateMetadataCommands
         return matches;
     }
     
-    private async Task<string> ReadCommandOutput(string workingDirectory, string program, string command, bool showLiveOutput = false)
+    private async Task<CommandOutput> ReadCommandOutput(string workingDirectory, string program, string command, bool showLiveOutput = false)
     {
         var processInfo = new ProcessStartInfo
         {
@@ -1129,35 +1161,36 @@ public sealed partial class UpdateMetadataCommands
             CreateNoWindow = true,
         };
 
+        //
+        // Both streams deliver their lines on threads of their own, so the lines are collected under
+        // a lock. The handlers are in place before reading starts; otherwise, the first lines may get
+        // lost, and with them the diagnostic which says why a build failed:
+        //
         var sb = new StringBuilder();
+        var sbLock = new Lock();
+        void CollectLine(string? line)
+        {
+            if(string.IsNullOrWhiteSpace(line))
+                return;
+
+            lock (sbLock)
+            {
+                if(showLiveOutput)
+                    Console.WriteLine(line);
+                sb.AppendLine(line);
+            }
+        }
+
         using var process = new Process();
         process.StartInfo = processInfo;
+        process.OutputDataReceived += (_, args) => CollectLine(args.Data);
+        process.ErrorDataReceived += (_, args) => CollectLine(args.Data);
         process.Start();
         process.BeginOutputReadLine();
         process.BeginErrorReadLine();
 
-        process.OutputDataReceived += (_, args) =>
-        {
-            if(!string.IsNullOrWhiteSpace(args.Data))
-            {
-                if(showLiveOutput)
-                    Console.WriteLine(args.Data);
-                sb.AppendLine(args.Data);
-            }
-        };
-        
-        process.ErrorDataReceived += (_, args) =>
-        {
-            if(!string.IsNullOrWhiteSpace(args.Data))
-            {
-                if(showLiveOutput)
-                    Console.WriteLine(args.Data);
-                sb.AppendLine(args.Data);
-            }
-        };
-        
         await process.WaitForExitAsync();
-        return sb.ToString();
+        return new(sb.ToString(), process.ExitCode);
     }
     
     private async Task<int> IncreaseBuildNumber()

app/Build/Tools/CommandOutput.cs

@@ -0,0 +1,12 @@
+namespace Build.Tools;
+
+/// <summary>
+/// What an external tool wrote, and how it ended.
+/// </summary>
+/// <remarks>
+/// The text alone cannot tell whether a tool failed: a build may stop on a diagnostic which no filter
+/// recognizes, or without writing any at all. Only the exit code answers that question reliably.
+/// </remarks>
+/// <param name="Text">Everything the tool wrote to its standard output and its standard error, line by line.</param>
+/// <param name="ExitCode">The exit code of the tool, where anything but zero is a failure.</param>
+public readonly record struct CommandOutput(string Text, int ExitCode);