stride3d/stride · warning · LexerException

Warning at

Error message

Warning at {line}:{column}: {msg}

What it means

The C preprocessor emits warnings via Preprocessor.warning(). If a PreprocessorListener is installed, the warning is handed to listener.handleWarning(); if no listener exists, the warning is fatal and thrown as a LexerException. Additionally, if the Warning.ERROR flag is set, warnings are escalated to errors.

Solutions

1. Install a PreprocessorListener (with handleWarning) on the Preprocessor so warnings are reported instead of thrown
2. Remove or fix the offending #warning/construct in the shader source
3. Unset the Warning.ERROR feature flag if warnings should not be fatal
4. Catch LexerException around Preprocessor.process()/token() calls

Example fix

// before
var pp = new Preprocessor();
pp.addInput(new FileLexer(sourceFile));
// after
var pp = new Preprocessor();
pp.setListener(new MyPreprocessorListener());
pp.addInput(new FileLexer(sourceFile));

if (pp.Listener == null) pp.setListener(new DefaultPreprocessorListener());

bool hasListener = preprocessor.getListener() != null;

try { pp.addInput(lexer); pp.process(); } catch (LexerException e) { log.Warn($"Preprocessor warning escalated: {e.Message}"); }

When it happens

Trigger: Preprocessing shader source that triggers a preprocessor warning (e.g. #warning directive or questionable token handling) while no PreprocessorListener is attached to the Preprocessor, or while Warning.ERROR is set.

Common situations: Developers running the SDSL/CppNet preprocessor over shader files directly (console tools) without installing a listener; CI pipelines that enable warnings-as-errors and hit a #warning in shader code.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Warning at
• {msg}
• Cannot read from
• Cannot redefine name 'defined'
• Bad token

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/37ebf196ffd3577e. Report an issue: GitHub.

Appendix: source

Thrown at sources/shaders/Stride.Shaders.Parsers/CppNet/Preprocessor.cs:305

	 * @see #error(int, int, String)
	 */
	protected void error(Token tok, String msg) {
		error(tok.getLine(), tok.getColumn(), msg);
	}

	/**
	 * Handles a warning.
	 *
	 * If a PreprocessorListener is installed, it receives the
	 * warning. Otherwise, an exception is thrown.
	 */
	protected void warning(int line, int column, String msg) {
		if (warnings.HasFlag(Warning.ERROR))
			error(line, column, msg);
		else if (listener != null)
			listener.handleWarning(source, line, column, msg);
		else
			throw new LexerException("Warning at " + line + ":" + column + ": " + msg);
	}

	/**
	 * Handles a warning.
	 *
	 * If a PreprocessorListener is installed, it receives the
	 * warning. Otherwise, an exception is thrown.
	 *
	 * @see #warning(int, int, String)
	 */
	protected void warning(Token tok, String msg) {
		warning(tok.getLine(), tok.getColumn(), msg);
	}

	/**
	 * Adds a Macro to this Preprocessor.
	 *
	 * The given {@link Macro} object encapsulates both the name

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