Lazily check for foreign exes which may not be necessary for the curr…

CHANGES.md

@@ -20,6 +20,7 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 * Bump default `diktat` version to latest `1.1.0` -> `1.2.1` ([#1246](https://github.com/diffplug/spotless/pull/1246))
   * Minimum supported version also bumped to `1.2.1` (diktat is based on ktlint and has the same backward compatibility issues).
 * Bump default `ktfmt` version to latest `0.37` -> `0.39` ([#1240](https://github.com/diffplug/spotless/pull/1240))
+* Clang and Black no longer break the build when the binary is unavailable, if they will not be run during that build ([#1257](https://github.com/diffplug/spotless/pull/1257))
 
 ## [2.26.2] - 2022-06-11
 ### Fixed

lib/src/main/java/com/diffplug/spotless/cpp/ClangFormatStep.java

@@ -21,6 +21,7 @@
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Objects;
 
 import javax.annotation.Nullable;
 
@@ -68,21 +69,20 @@ public FormatterStep create() {
 
 	private State createState() throws IOException, InterruptedException {
 		String howToInstall = "" +
-				"You can download clang-format from https://releases.llvm.org and " +
-				"then point Spotless to it with {@code pathToExe('/path/to/clang-format')} " +
-				"or you can use your platform's package manager:" +
-				"\n  win:   choco install llvm --version {version}  (try dropping version if it fails)" +
-				"\n  mac:   brew install clang-format (TODO: how to specify version?)" +
-				"\n  linux: apt install clang-format  (try clang-format-{version} with dropped minor versions)" +
-				"\n    github issue to handle this better: https://github.com/diffplug/spotless/issues/673";
-		String exeAbsPath = ForeignExe.nameAndVersion("clang-format", version)
-				.pathToExe(pathToExe)
-				.fixCantFind(howToInstall)
-				.fixWrongVersion(
-						"You can tell Spotless to use the version you already have with {@code clangFormat('{versionFound}')}" +
-								"or you can download the currently specified version, {version}.\n" + howToInstall)
-				.confirmVersionAndGetAbsolutePath();
-		return new State(this, exeAbsPath);
+			"You can download clang-format from https://releases.llvm.org and " +
+			"then point Spotless to it with {@code pathToExe('/path/to/clang-format')} " +
+			"or you can use your platform's package manager:" +
+			"\n  win:   choco install llvm --version {version}  (try dropping version if it fails)" +
+			"\n  mac:   brew install clang-format (TODO: how to specify version?)" +
+			"\n  linux: apt install clang-format  (try clang-format-{version} with dropped minor versions)" +
+			"\n    github issue to handle this better: https://github.com/diffplug/spotless/issues/673";
+		final ForeignExe exe =  ForeignExe.nameAndVersion("clang-format", version)
+			.pathToExe(pathToExe)
+			.fixCantFind(howToInstall)
+			.fixWrongVersion(
+					"You can tell Spotless to use the version you already have with {@code clangFormat('{versionFound}')}" +
+							"or you can download the currently specified version, {version}.\n" + howToInstall);
+		return new State(this, exe);
 	}
 
 	@SuppressFBWarnings("SE_TRANSIENT_FIELD_NOT_RESTORED")
@@ -91,24 +91,28 @@ static class State implements Serializable {
 		// used for up-to-date checks and caching
 		final String version;
 		final @Nullable String style;
+		final ForeignExe exe;
 		// used for executing
-		final transient List<String> args;
+		private @Nullable List<String> args;
 
-		State(ClangFormatStep step, String exeAbsPath) {
+		State(ClangFormatStep step, ForeignExe pathToExe) {
 			this.version = step.version;
 			this.style = step.style;
-			args = new ArrayList<>(2);
-			args.add(exeAbsPath);
-			if (style != null) {
-				args.add("--style=" + style);
-			}
+			this.exe = Objects.requireNonNull(pathToExe);
 		}
 
 		String format(ProcessRunner runner, String input, File file) throws IOException, InterruptedException {
-			String[] processArgs = args.toArray(new String[args.size() + 1]);
-			// add an argument to the end
-			processArgs[args.size()] = "--assume-filename=" + file.getName();
-			return runner.exec(input.getBytes(StandardCharsets.UTF_8), processArgs).assertExitZero(StandardCharsets.UTF_8);
+			if (args == null) {
+				final List<String> tmpArgs = new ArrayList<>();
+				tmpArgs.add(exe.confirmVersionAndGetAbsolutePath());
+				if (style != null) {
+					tmpArgs.add("--style="+ style);	
+				}
+				args = tmpArgs;
+			}
+			final String[] processArgs = args.toArray(new String[args.size() + 1]);
+			processArgs[processArgs.length - 1] = "--assume-filename=" + file.getName();
+			return runner.exec(input.getBytes(StandardCharsets.UTF_8), args).assertExitZero(StandardCharsets.UTF_8);
 		}
 
 		FormatterFunc.Closeable toFunc() {

lib/src/main/java/com/diffplug/spotless/python/BlackStep.java

@@ -18,8 +18,7 @@
 import java.io.IOException;
 import java.io.Serializable;
 import java.nio.charset.StandardCharsets;
-import java.util.Arrays;
-import java.util.List;
+import java.util.Objects;
 import java.util.regex.Pattern;
 
 import javax.annotation.Nullable;
@@ -62,12 +61,11 @@ public FormatterStep create() {
 
 	private State createState() throws IOException, InterruptedException {
 		String trackingIssue = "\n  github issue to handle this better: https://github.com/diffplug/spotless/issues/674";
-		String exeAbsPath = ForeignExe.nameAndVersion("black", version)
+		ForeignExe exeAbsPath = ForeignExe.nameAndVersion("black", version)
 				.pathToExe(pathToExe)
 				.versionRegex(Pattern.compile("(?:black, version|black,|version) (\\S*)"))
 				.fixCantFind("Try running {@code pip install black=={version}}, or else tell Spotless where it is with {@code black().pathToExe('path/to/executable')}" + trackingIssue)
-				.fixWrongVersion("Try running {@code pip install --force-reinstall black=={version}}, or else specify {@code black('{versionFound}')} to Spotless" + trackingIssue)
-				.confirmVersionAndGetAbsolutePath();
+				.fixWrongVersion("Try running {@code pip install --force-reinstall black=={version}}, or else specify {@code black('{versionFound}')} to Spotless" + trackingIssue);
 		return new State(this, exeAbsPath);
 	}
 
@@ -76,15 +74,19 @@ static class State implements Serializable {
 		private static final long serialVersionUID = -1825662356883926318L;
 		// used for up-to-date checks and caching
 		final String version;
+		final ForeignExe exe;
 		// used for executing
-		final transient List<String> args;
+		private @Nullable String[] args;
 
-		State(BlackStep step, String exeAbsPath) {
+		State(BlackStep step, ForeignExe exeAbsPath) {
 			this.version = step.version;
-			this.args = Arrays.asList(exeAbsPath, "-");
+			this.exe = Objects.requireNonNull(exeAbsPath);
 		}
 
 		String format(ProcessRunner runner, String input) throws IOException, InterruptedException {
+			if (args == null) {
+				args = new String[] {exe.confirmVersionAndGetAbsolutePath(), "-"};
+			}
 			return runner.exec(input.getBytes(StandardCharsets.UTF_8), args).assertExitZero(StandardCharsets.UTF_8);
 		}