pkg: clean up builtin errors

- delete dead code and unused fields
- remove unused arguments
- dedup errors
- use OpContext-based error methods (for positions)

Fixes #902
Issue #52

Change-Id: Idf96e569400a6a5230a8783b0881a895026a41ae
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/9449
Reviewed-by: CUE cueckoo <cueckoo@gmail.com>
Reviewed-by: Paul Jolly <paul@myitcv.org.uk>

cue/testdata/comprehensions/fields.txtar

@@ -25,7 +25,8 @@ user: {
   #User: (#struct){
     tags_str: (string){ string }
     tags_map: (_|_){
-      // [incomplete] error in call to strings.Split: non-concrete value string
+      // [incomplete] error in call to strings.Split: non-concrete value string:
+      //     ./in.cue:6:22
       "{a}": (string){ string }
     }
   }

cue/testdata/cycle/compbottomnofinal.txtar

@@ -359,7 +359,6 @@ large: {
 }
 -- out/eval --
 Errors:
-error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax
 large.p1.Y: cycle: new field port inserted by if clause that was previously evaluated by another if clause
 large.p2.#Y: cycle: field userinfo was added after an if clause evaluated it
 large.p2.Y: cycle: new field port inserted by if clause that was previously evaluated by another if clause
@@ -372,6 +371,16 @@ medium.p3.Y: cycle: new field port inserted by if clause that was previously eva
 medium.p4.Y: cycle: new field port inserted by if clause that was previously evaluated by another if clause
 minimal.b: cycle: new field port inserted by if clause that was previously evaluated by another if clause
 small.p1.#Y: cycle: field port was added after an if clause evaluated it
+error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax:
+    ./in.cue:104:23
+error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax:
+    ./in.cue:126:23
+error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax:
+    ./in.cue:228:23
+error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax:
+    ./in.cue:269:23
+error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax:
+    ./in.cue:310:23
 
 Result:
 (_|_){
@@ -441,7 +450,8 @@ Result:
       Y: (_|_){
         // [eval] medium.p3.Y: cycle: new field port inserted by if clause that was previously evaluated by another if clause
         port: (_|_){
-          // [eval] error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax
+          // [eval] error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax:
+          //     ./in.cue:104:23
         }
       }
       #Y: (#struct){
@@ -456,7 +466,8 @@ Result:
       Y: (_|_){
         // [eval] medium.p4.Y: cycle: new field port inserted by if clause that was previously evaluated by another if clause
         port: (_|_){
-          // [eval] error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax
+          // [eval] error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax:
+          //     ./in.cue:126:23
         }
       }
       #X: (#struct){
@@ -501,7 +512,8 @@ Result:
         userinfo: (string){ "user" }
         host: (string){ "example.com" }
         port: (_|_){
-          // [eval] error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax
+          // [eval] error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax:
+          //     ./in.cue:228:23
         }
       }
       X: (string){ "user@example.com" }
@@ -524,7 +536,8 @@ Result:
         userinfo: (string){ "user" }
         host: (string){ "example.com" }
         port: (_|_){
-          // [eval] error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax
+          // [eval] error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax:
+          //     ./in.cue:269:23
         }
       }
       #X: (#struct){
@@ -552,7 +565,8 @@ Result:
         userinfo: (string){ "user" }
         host: (string){ "example.com" }
         port: (_|_){
-          // [eval] error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax
+          // [eval] error in call to strconv.Atoi: strconv.Atoi: parsing "": invalid syntax:
+          //     ./in.cue:310:23
         }
       }
       #Y: (_|_){

cue/testdata/fulleval/026_dont_convert_incomplete_errors_to_non-incomplete.txtar

@@ -92,7 +92,8 @@ s3:  strings.ContainsAny(str, "dd")
   }
   s2: (string){ strings.ContainsAny("dd") }
   s3: (_|_){
-    // [incomplete] error in call to strings.ContainsAny: non-concrete value string
+    // [incomplete] error in call to strings.ContainsAny: non-concrete value string:
+    //     ./in.cue:15:5
   }
   str: (string){ string }
   num: (number){ <4 }

cue/testdata/fulleval/044_Issue_#178.txtar

@@ -27,12 +27,14 @@ bar:  hex.EncodedLen(len)
 -- out/eval --
 (struct){
   foo: (_|_){
-    // [incomplete] error in call to encoding/csv.Decode: non-concrete value bytes
+    // [incomplete] error in call to encoding/csv.Decode: non-concrete value bytes:
+    //     ./in.cue:5:7
   }
   data: (bytes){ bytes }
   len: (int){ int }
   bar: (_|_){
-    // [incomplete] error in call to encoding/hex.EncodedLen: non-concrete value int
+    // [incomplete] error in call to encoding/hex.EncodedLen: non-concrete value int:
+    //     ./in.cue:9:6
   }
 }
 -- out/compile --

cue/testdata/fulleval/056_issue314.txtar

@@ -84,7 +84,8 @@ x:
   #T: (#struct){
     s: (string){ string }
     out: (_|_){
-      // [incomplete] error in call to text/template.Execute: cannot convert incomplete value "string" to JSON
+      // [incomplete] error in call to text/template.Execute: cannot convert incomplete value "string" to JSON:
+      //     ./in.cue:14:7
     }
   }
   #V: (#struct){

cue/testdata/resolve/048_builtins.txtar

@@ -99,12 +99,14 @@ a3.a: invalid value "bar" (out of bound =~"oo"):
 a3.a: invalid value "bar" (out of bound =~"fo"):
     ./in.cue:9:5
     ./in.cue:12:14
-stringListErrors.b.result: invalid type element 0 (int) of string list argument 0:
+stringListErrors.b.result: invalid list element 0 in argument 0 to call: cannot use value int (int) as string:
     ./in.cue:31:17
+    ./in.cue:30:13
 stringListErrors.c.result: cannot use int (type int) as string in argument 2 to strings.Join:
     ./in.cue:36:33
-decimalListErrors.a.result: invalid type element 0 (string) of number list argument 0:
+decimalListErrors.a.result: invalid list element 0 in argument 0 to call: cannot use value string (string) as number:
     ./in.cue:43:17
+    ./in.cue:42:13
 
 Result:
 (_|_){
@@ -167,8 +169,9 @@ Result:
         0: (string){ string }
       }
       result: (_|_){
-        // [incomplete] stringListErrors.a.result: non-concrete string value for element 0 of string list argument 0:
+        // [incomplete] stringListErrors.a.result: non-concrete value string for element 0 of string list argument 0:
         //     ./in.cue:26:17
+        //     ./in.cue:25:13
       }
     }
     b: (_|_){
@@ -177,8 +180,9 @@ Result:
         0: (int){ int }
       }
       result: (_|_){
-        // [eval] stringListErrors.b.result: invalid type element 0 (int) of string list argument 0:
+        // [eval] stringListErrors.b.result: invalid list element 0 in argument 0 to call: cannot use value int (int) as string:
         //     ./in.cue:31:17
+        //     ./in.cue:30:13
       }
     }
     c: (_|_){
@@ -199,17 +203,19 @@ Result:
         0: (string){ string }
       }
       result: (_|_){
-        // [eval] decimalListErrors.a.result: invalid type element 0 (string) of number list argument 0:
+        // [eval] decimalListErrors.a.result: invalid list element 0 in argument 0 to call: cannot use value string (string) as number:
         //     ./in.cue:43:17
+        //     ./in.cue:42:13
       }
     }
     b: (struct){
       x: (list){
         0: (int){ int }
       }
       result: (_|_){
-        // [incomplete] decimalListErrors.b.result: non-concrete number value for element 0 of number list argument 0:
+        // [incomplete] decimalListErrors.b.result: non-concrete value int for element 0 of number list argument 0:
         //     ./in.cue:48:17
+        //     ./in.cue:47:13
       }
     }
   }

internal/core/adt/context.go

@@ -585,8 +585,7 @@ func (c *OpContext) evalState(v Expr, state VertexStatus) (result Value) {
 		if b, ok := result.(*Bottom); ok {
 			if c.src != nil &&
 				b.Code == CycleError &&
-				b.Err.Position() == token.NoPos &&
-				len(b.Err.InputPositions()) == 0 {
+				len(errors.Positions(b.Err)) == 0 {
 				bb := *b
 				bb.Err = errors.Wrapf(b.Err, c.src.Pos(), "")
 				result = &bb

internal/core/adt/expr.go

@@ -1398,6 +1398,7 @@ func (x *Builtin) call(c *OpContext, p token.Pos, args []Value) Expr {
 				c.addErrf(0, pos(a),
 					"cannot use %s as %s in argument %d to %s",
 					a, v, i+1, fun)
+				return nil
 			}
 			args[i] = n
 		}

pkg/encoding/base64/manual.go

@@ -17,17 +17,18 @@ package base64
 
 import (
 	"encoding/base64"
-	"fmt"
 
 	"cuelang.org/go/cue"
+	"cuelang.org/go/cue/errors"
+	"cuelang.org/go/cue/token"
 )
 
 // EncodedLen returns the length in bytes of the base64 encoding
 // of an input buffer of length n. Encoding needs to be set to null
 // as only StdEncoding is supported for now.
 func EncodedLen(encoding cue.Value, n int) (int, error) {
 	if err := encoding.Null(); err != nil {
-		return 0, fmt.Errorf("base64: unsupported encoding: %v", err)
+		return 0, errors.Wrapf(err, token.NoPos, "base64: unsupported encoding")
 	}
 	return base64.StdEncoding.EncodedLen(n), nil
 }
@@ -37,7 +38,7 @@ func EncodedLen(encoding cue.Value, n int) (int, error) {
 // null as only StdEncoding is supported for now.
 func DecodedLen(encoding cue.Value, x int) (int, error) {
 	if err := encoding.Null(); err != nil {
-		return 0, fmt.Errorf("base64: unsupported encoding: %v", err)
+		return 0, errors.Wrapf(err, token.NoPos, "base64: unsupported encoding")
 	}
 	return base64.StdEncoding.DecodedLen(x), nil
 }
@@ -46,7 +47,7 @@ func DecodedLen(encoding cue.Value, x int) (int, error) {
 // as only StdEncoding is supported for now.
 func Encode(encoding cue.Value, src []byte) (string, error) {
 	if err := encoding.Null(); err != nil {
-		return "", fmt.Errorf("base64: unsupported encoding: %v", err)
+		return "", errors.Wrapf(err, token.NoPos, "base64: unsupported encoding")
 	}
 	return base64.StdEncoding.EncodeToString(src), nil
 }
@@ -55,7 +56,7 @@ func Encode(encoding cue.Value, src []byte) (string, error) {
 // to be set to null as only StdEncoding is supported for now.
 func Decode(encoding cue.Value, s string) ([]byte, error) {
 	if err := encoding.Null(); err != nil {
-		return nil, fmt.Errorf("base64: unsupported encoding: %v", err)
+		return nil, errors.Wrapf(err, token.NoPos, "base64: unsupported encoding")
 	}
 	return base64.StdEncoding.DecodeString(s)
 }

pkg/encoding/base64/testdata/gen.txtar

@@ -9,8 +9,10 @@ t3: base64.Decode(null, "foo")
 t4: base64.Decode({}, "foo")
 -- out/base64 --
 Errors:
-error in call to encoding/base64.Decode: base64: unsupported encoding: cannot use value {} (type struct) as null
-error in call to encoding/base64.Decode: illegal base64 data at input byte 0
+error in call to encoding/base64.Decode: illegal base64 data at input byte 0:
+    ./in.cue:5:5
+error in call to encoding/base64.Decode: base64: unsupported encoding: cannot use value {} (type struct) as null:
+    ./in.cue:6:5
 
 Result:
 t1: "Zm9v"

pkg/encoding/hex/testdata/gen.txtar

@@ -9,7 +9,8 @@ t3: hex.Decode("foo")
 t4: hex.Dump('foo')
 -- out/hex --
 Errors:
-error in call to encoding/hex.Decode: encoding/hex: invalid byte: U+006F 'o'
+error in call to encoding/hex.Decode: encoding/hex: invalid byte: U+006F 'o':
+    ./in.cue:5:5
 
 Result:
 t1: "666f6f"

pkg/encoding/json/manual.go

@@ -21,7 +21,9 @@ import (
 
 	"cuelang.org/go/cue"
 	"cuelang.org/go/cue/ast"
+	"cuelang.org/go/cue/errors"
 	"cuelang.org/go/cue/parser"
+	"cuelang.org/go/cue/token"
 	"cuelang.org/go/internal"
 )
 
@@ -98,7 +100,7 @@ func Unmarshal(b []byte) (ast.Expr, error) {
 	expr, err := parser.ParseExpr("json", b)
 	if err != nil {
 		// NOTE: should never happen.
-		return nil, fmt.Errorf("json: could not parse JSON: %v", err)
+		return nil, errors.Wrapf(err, token.NoPos, "json: could not parse JSON")
 	}
 	return expr, nil
 }

pkg/encoding/json/testdata/gen.txtar

@@ -18,6 +18,7 @@ t9: json.MarshalStream([{a: 1}, {b: int | *2}])
 -- out/json --
 Errors:
 a: error in call to encoding/json.Validate: invalid value 10 (out of bound <3):
+    ./in.cue:4:5
     ./in.cue:4:36
     json.Validate:1:6
 

pkg/encoding/yaml/testdata/gen.txtar

@@ -14,11 +14,14 @@ t8: yaml.Marshal({b: int | *2})
 t9: yaml.MarshalStream([{a: 1}, {b: int | *2}])
 -- out/yaml --
 Errors:
-b: error in call to encoding/yaml.Validate: incomplete value int
 a: error in call to encoding/yaml.Validate: invalid value 4 (out of bound <3):
+    ./in.cue:3:5
     ./in.cue:3:41
     yaml.Validate:3:5
+b: error in call to encoding/yaml.Validate: incomplete value int:
+    ./in.cue:5:5
 a: error in call to encoding/yaml.ValidatePartial: invalid value 4 (out of bound <3):
+    ./in.cue:6:5
     ./in.cue:6:48
     yaml.ValidatePartial:3:5
 

pkg/internal/builtin.go

@@ -20,7 +20,6 @@ import (
 
 	"cuelang.org/go/cue/errors"
 	"cuelang.org/go/cue/parser"
-	"cuelang.org/go/cue/token"
 	"cuelang.org/go/internal"
 	"cuelang.org/go/internal/core/adt"
 	"cuelang.org/go/internal/core/compile"
@@ -126,7 +125,6 @@ func toBuiltin(ctx *adt.OpContext, b *Builtin) *adt.Builtin {
 	x.Func = func(ctx *adt.OpContext, args []adt.Value) (ret adt.Expr) {
 		// call, _ := ctx.Source().(*ast.CallExpr)
 		c := &CallCtxt{
-			// src:  call,
 			ctx:     ctx,
 			args:    args,
 			builtin: b,
@@ -181,17 +179,6 @@ func mustParseConstBuiltin(ctx adt.Runtime, name, val string) adt.Expr {
 
 }
 
-func pos(n adt.Node) (p token.Pos) {
-	if n == nil {
-		return
-	}
-	src := n.Source()
-	if src == nil {
-		return
-	}
-	return src.Pos()
-}
-
 func (x *Builtin) name(ctx *adt.OpContext) string {
 	if x.Pkg == 0 {
 		return x.Name