Add backtraces to error starlark command output

drone/starlark/starlark.go

@@ -24,6 +24,9 @@ var Command = cli.Command{
 	ArgsUsage: "[path/to/.drone.star]",
 	Action: func(c *cli.Context) {
 		if err := generate(c); err != nil {
+			if err, ok := err.(*starlark.EvalError); ok {
+				log.Fatalf("starlark evaluation error:\n%s", err.Backtrace())
+			}
 			log.Fatalln(err)
 		}
 	},

go.mod

@@ -34,11 +34,11 @@ require (
 	github.com/pkg/errors v0.8.0
 	github.com/urfave/cli v1.20.0
 	github.com/vinzenz/yaml v0.0.0-20170920082545-91409cdd725d
-	go.starlark.net v0.0.0-20190219202100-4eb76950c5f0
+	go.starlark.net v0.0.0-20200306205701-8dd3e2ee1dd5
 	golang.org/x/net v0.0.0-20181005035420-146acd28ed58
 	golang.org/x/oauth2 v0.0.0-20181203162652-d668ce993890
 	golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f
-	golang.org/x/sys v0.0.0-20181005133103-4497e2df6f9e
+	golang.org/x/sys v0.0.0-20191002063906-3421d5a6bb1c
 	google.golang.org/appengine v1.3.0
 	gopkg.in/yaml.v2 v2.2.2
 )

go.sum

@@ -10,6 +10,9 @@ github.com/bmatcuk/doublestar v1.1.1/go.mod h1:UD6OnuiIn0yFxxA2le/rnRU1G4RaI4UvF
 github.com/buildkite/yaml v0.0.0-20181016232759-0caa5f0796e3/go.mod h1:5hCug3EZaHXU3FdCA3gJm0YTNi+V+ooA2qNTiVpky4A=
 github.com/buildkite/yaml v2.1.0+incompatible h1:xirI+ql5GzfikVNDmt+yeiXpf/v1Gt03qXTtT5WXdr8=
 github.com/buildkite/yaml v2.1.0+incompatible/go.mod h1:UoU8vbcwu1+vjZq01+KrpSeLBgQQIjL/H7Y6KwikUrI=
+github.com/chzyer/logex v1.1.10/go.mod h1:+Ywpsq7O8HXn0nuIou7OrIPyXbp3wmkHB+jjWRnGsAI=
+github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e/go.mod h1:nSuG5e5PlCu98SY8svDHJxuZscDgtXS6KTTbou5AhLI=
+github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1/go.mod h1:Q3SI9o4m/ZMnBNeIyt5eFwwo7qiLfzFZmjNmxjkiQlU=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/docker/distribution v0.0.0-20170726174610-edc3ab29cdff/go.mod h1:J2gT2udsDAN96Uj4KfcMRqY0/ypR+oyYUYmja8H+y+w=
@@ -99,6 +102,8 @@ github.com/vinzenz/yaml v0.0.0-20170920082545-91409cdd725d h1:3wDi6J5APMqaHBVPuV
 github.com/vinzenz/yaml v0.0.0-20170920082545-91409cdd725d/go.mod h1:mb5taDqMnJiZNRQ3+02W2IFG+oEz1+dTuCXkp4jpkfo=
 go.starlark.net v0.0.0-20190219202100-4eb76950c5f0 h1:3QD1YY1gYmY6Jb/Lsra7ct+T7FewBaX3k9YXqpziB08=
 go.starlark.net v0.0.0-20190219202100-4eb76950c5f0/go.mod h1:c1/X6cHgvdXj6pUlmWKMkuqRnW4K8x2vwt6JAaaircg=
+go.starlark.net v0.0.0-20200306205701-8dd3e2ee1dd5 h1:+FNtrFTmVw0YZGpBGX56XDee331t6JAXeK2bcyhLOOc=
+go.starlark.net v0.0.0-20200306205701-8dd3e2ee1dd5/go.mod h1:nmDLcffg48OtT/PSW0Hg7FvpRQsQh5OSqIylirxKC7o=
 golang.org/x/crypto v0.0.0-20181203042331-505ab145d0a9/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20181005035420-146acd28ed58 h1:otZG8yDCO4LVps5+9bxOeNiCvgmOyt96J3roHTYs7oE=
@@ -109,6 +114,7 @@ golang.org/x/oauth2 v0.0.0-20181203162652-d668ce993890/go.mod h1:N/0e6XlmueqKjAG
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f h1:wMNYb4v58l5UBM7MYRLPG6ZhfOqbKu7X5eyFl8ZhKvA=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20181005133103-4497e2df6f9e/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20191002063906-3421d5a6bb1c/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/time v0.0.0-20181108054448-85acf8d2951c/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 google.golang.org/appengine v1.2.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=