1// Copyright 2012 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// This file implements various error reporters.
6
7package types
8
9import (
10	"errors"
11	"fmt"
12	"go/ast"
13	"go/token"
14	"strconv"
15	"strings"
16)
17
18func assert(p bool) {
19	if !p {
20		panic("assertion failed")
21	}
22}
23
24func unreachable() {
25	panic("unreachable")
26}
27
28func (check *Checker) qualifier(pkg *Package) string {
29	// Qualify the package unless it's the package being type-checked.
30	if pkg != check.pkg {
31		// If the same package name was used by multiple packages, display the full path.
32		if check.pkgCnt[pkg.name] > 1 {
33			return strconv.Quote(pkg.path)
34		}
35		return pkg.name
36	}
37	return ""
38}
39
40func (check *Checker) sprintf(format string, args ...interface{}) string {
41	for i, arg := range args {
42		switch a := arg.(type) {
43		case nil:
44			arg = "<nil>"
45		case operand:
46			panic("internal error: should always pass *operand")
47		case *operand:
48			arg = operandString(a, check.qualifier)
49		case token.Pos:
50			arg = check.fset.Position(a).String()
51		case ast.Expr:
52			arg = ExprString(a)
53		case Object:
54			arg = ObjectString(a, check.qualifier)
55		case Type:
56			arg = TypeString(a, check.qualifier)
57		}
58		args[i] = arg
59	}
60	return fmt.Sprintf(format, args...)
61}
62
63func (check *Checker) trace(pos token.Pos, format string, args ...interface{}) {
64	fmt.Printf("%s:\t%s%s\n",
65		check.fset.Position(pos),
66		strings.Repeat(".  ", check.indent),
67		check.sprintf(format, args...),
68	)
69}
70
71// dump is only needed for debugging
72func (check *Checker) dump(format string, args ...interface{}) {
73	fmt.Println(check.sprintf(format, args...))
74}
75
76func (check *Checker) err(err error) {
77	if err == nil {
78		return
79	}
80	var e Error
81	isInternal := errors.As(err, &e)
82	// Cheap trick: Don't report errors with messages containing
83	// "invalid operand" or "invalid type" as those tend to be
84	// follow-on errors which don't add useful information. Only
85	// exclude them if these strings are not at the beginning,
86	// and only if we have at least one error already reported.
87	isInvalidErr := isInternal && (strings.Index(e.Msg, "invalid operand") > 0 || strings.Index(e.Msg, "invalid type") > 0)
88	if check.firstErr != nil && isInvalidErr {
89		return
90	}
91
92	if check.errpos != nil && isInternal {
93		// If we have an internal error and the errpos override is set, use it to
94		// augment our error positioning.
95		// TODO(rFindley) we may also want to augment the error message and refer
96		// to the position (pos) in the original expression.
97		span := spanOf(check.errpos)
98		e.Pos = span.pos
99		e.go116start = span.start
100		e.go116end = span.end
101		err = e
102	}
103
104	if check.firstErr == nil {
105		check.firstErr = err
106	}
107
108	if trace {
109		pos := e.Pos
110		msg := e.Msg
111		if !isInternal {
112			msg = err.Error()
113			pos = token.NoPos
114		}
115		check.trace(pos, "ERROR: %s", msg)
116	}
117
118	f := check.conf.Error
119	if f == nil {
120		panic(bailout{}) // report only first error
121	}
122	f(err)
123}
124
125func (check *Checker) newError(at positioner, code errorCode, soft bool, msg string) error {
126	span := spanOf(at)
127	return Error{
128		Fset:       check.fset,
129		Pos:        span.pos,
130		Msg:        msg,
131		Soft:       soft,
132		go116code:  code,
133		go116start: span.start,
134		go116end:   span.end,
135	}
136}
137
138// newErrorf creates a new Error, but does not handle it.
139func (check *Checker) newErrorf(at positioner, code errorCode, soft bool, format string, args ...interface{}) error {
140	msg := check.sprintf(format, args...)
141	return check.newError(at, code, soft, msg)
142}
143
144func (check *Checker) error(at positioner, code errorCode, msg string) {
145	check.err(check.newError(at, code, false, msg))
146}
147
148func (check *Checker) errorf(at positioner, code errorCode, format string, args ...interface{}) {
149	check.error(at, code, check.sprintf(format, args...))
150}
151
152func (check *Checker) softErrorf(at positioner, code errorCode, format string, args ...interface{}) {
153	check.err(check.newErrorf(at, code, true, format, args...))
154}
155
156func (check *Checker) invalidAST(at positioner, format string, args ...interface{}) {
157	check.errorf(at, 0, "invalid AST: "+format, args...)
158}
159
160func (check *Checker) invalidArg(at positioner, code errorCode, format string, args ...interface{}) {
161	check.errorf(at, code, "invalid argument: "+format, args...)
162}
163
164func (check *Checker) invalidOp(at positioner, code errorCode, format string, args ...interface{}) {
165	check.errorf(at, code, "invalid operation: "+format, args...)
166}
167
168// The positioner interface is used to extract the position of type-checker
169// errors.
170type positioner interface {
171	Pos() token.Pos
172}
173
174// posSpan holds a position range along with a highlighted position within that
175// range. This is used for positioning errors, with pos by convention being the
176// first position in the source where the error is known to exist, and start
177// and end defining the full span of syntax being considered when the error was
178// detected. Invariant: start <= pos < end || start == pos == end.
179type posSpan struct {
180	start, pos, end token.Pos
181}
182
183func (e posSpan) Pos() token.Pos {
184	return e.pos
185}
186
187// inNode creates a posSpan for the given node.
188// Invariant: node.Pos() <= pos < node.End() (node.End() is the position of the
189// first byte after node within the source).
190func inNode(node ast.Node, pos token.Pos) posSpan {
191	start, end := node.Pos(), node.End()
192	if debug {
193		assert(start <= pos && pos < end)
194	}
195	return posSpan{start, pos, end}
196}
197
198// atPos wraps a token.Pos to implement the positioner interface.
199type atPos token.Pos
200
201func (s atPos) Pos() token.Pos {
202	return token.Pos(s)
203}
204
205// spanOf extracts an error span from the given positioner. By default this is
206// the trivial span starting and ending at pos, but this span is expanded when
207// the argument naturally corresponds to a span of source code.
208func spanOf(at positioner) posSpan {
209	switch x := at.(type) {
210	case nil:
211		panic("internal error: nil")
212	case posSpan:
213		return x
214	case ast.Node:
215		pos := x.Pos()
216		return posSpan{pos, pos, x.End()}
217	case *operand:
218		if x.expr != nil {
219			pos := x.Pos()
220			return posSpan{pos, pos, x.expr.End()}
221		}
222		return posSpan{token.NoPos, token.NoPos, token.NoPos}
223	default:
224		pos := at.Pos()
225		return posSpan{pos, pos, pos}
226	}
227}
228