v0.4.0

This release supports compile-time rewriting of source files via toolexec.
Build your package or binary with go build -toolexec errtrace and all packages
that import errtrace will be automatically instrumented with errtrace.

Added

• Add UnwrapFrame function to extract a single frame from an error.
  You can use this to implement your own trace formatting logic.

• Support extracting trace frames from custom errors.
  Any error value that implements TracePC() uintptr will now
  contribute to the trace.

• Add GetCaller function for error helpers to annotate wrapped errors with
  their caller information instead of the helper. Example:

  //go:noinline
  func Wrapf(err error, msg string, args ...any) {
    caller := errtrace.GetCaller()
    err := ...
    return caller.Wrap(err)
  }

• Implement slog.LogValuer so errors logged with log/slog log the full trace.

• cmd/errtrace:
  Add -no-wrapn option to disable wrapping with generic WrapN functions.
  This is only useful for toolexec mode due to tooling limitations.

• cmd/errtrace:
  Experimental support for instrumenting code with errtrace automatically
  as part of the Go build process.
  Try this out with go build -toolexec=errtrace pkg/to/build.
  Automatic instrumentation only rewrites packages that import errtrace.
  The flag -required-packages can be used to specify which packages
  are expected to import errtrace if they require rewrites.
  Example: go build -toolexec="errtrace -required-packages pkg/..." pkg/to/build

Changed

• Update go directive in go.mod to 1.21, and drop compatibility with Go 1.20 and earlier.
• Errors wrapped with errtrace are now compatible with log/slog-based loggers,
  and will report the full error trace when logged.

Fixed

• cmd/errtrace: Don't exit with a non-zero status when -h is used.
• cmd/errtrace: Don't panic on imbalanced assignments inside defer blocks.

v0.3.0

This release adds support to the CLI for using Go package patterns like ./...
to match and transform files.
You can now use errtrace -w ./... to instrument all files in a Go module,
or errtrace -l ./... to list all files that would be changed.

Added

• cmd/errtrace: Support Go package patterns in addition to file paths.
  Use errtrace -w ./... to transform all files under the current package
  and its descendants.

Changed

• cmd/errtrace:
  Print a message when reading from stdin because no arguments were given.
  Use '-' as the file name to read from stdin without a warning.

v0.2.0: CLI improvements

This release contains minor improvements to the errtrace code transformer
allowing it to fit more use cases.

Added

• cmd/errtrace: Add -l flag to print files that would be changed without changing them. You can use this to build a check to verify that your code is instrumented.

• cmd/errtrace: Support opt-out on lines with a //errtrace:skip comment. Optionally, a reason may be specified alongside the comment. The command will print a warning for any unused //errtrace:skip comments.

  if err != nil {
    return io.EOF //errtrace:skip(io.Reader expects io.EOF)
  }

v0.1.1

This release contains minor fix-ups to better consume the project.
Install this with:

go get braces.dev/[email protected]

See the prior release announcement for additional information.

Changed

• Lower go directive in go.mod to 1.20 to allow use with older versions.

Fixed

• Add a README.md to render alongside the API reference.

v0.1.0: Introducing errtrace

Introducing errtrace, an experimental library that provides better stack traces for your errors.

Install the library with:

go get braces.dev/[email protected]

We've also included a tool that will automatically instrument your code with errtrace.
In your project, run:

go install braces.dev/errtrace/cmd/[email protected]
git ls-files -- '*.go' | xargs errtrace -w

See README for more information.