// type parameter. Otherwise the result is nil. Errors are reported through the err parameter.
// Note: infer may fail (return nil) due to invalid args operands without reporting additional errors.
func (check *Checker) infer(posn positioner, tparams []*TypeParam, targs []Type, params *Tuple, args []*operand, reverse bool, err *error_) (inferred []Type) {
	// Don't verify result conditions if there's no error handler installed:

	var x operand
	if init != nil {
		if inherited {
			// The initialization expression is inherited from a previous
			// constant declaration, and (error) positions refer to that
			// expression and not the current constant declaration. Use
			// the constant identifier position for any errors during
			// init expression evaluation since that is all we have
			// (see issues go.dev/issue/42991, go.dev/issue/42992).

func (s *FileSet) PositionFor(p Pos, adjusted bool) (pos Position) {
	if p != NoPos {
		if f := s.file(p); f != nil {
			return f.position(p, adjusted)
		}
	}
	return
}

// Position converts a [Pos] p in the fileset into a Position value.
// Calling s.Position(p) is equivalent to calling s.PositionFor(p, true).
func (s *FileSet) Position(p Pos) (pos Position) {
	return s.PositionFor(p, true)
}

		return
	}

	if !Identical(x.typ, y.typ) {
		// only report an error if we have valid types
		// (otherwise we had an error reported elsewhere already)
		if isValid(x.typ) && isValid(y.typ) {
			var posn positioner = x
			if e != nil {
				posn = e
			}
			if e != nil {
				check.errorf(posn, MismatchedTypes, invalidOp+"%s (mismatched types %s and %s)", e, x.typ, y.typ)
			} else {

			return n.Pos()
		}
	}
}

// EndPos returns the approximate end position of n in the source.
// For some nodes (*Name, *BasicLit) it returns the position immediately
// following the node; for others (*BlockStmt, *SwitchStmt, etc.) it
// returns the position of the closing '}'; and for some (*ParenExpr)
// the returned position is the end position of the last enclosed
// expression.

//
// The position base is used to determine the "relative" position, that is the
// filename and line number relative to the position base. If the base refers
// to the current file, there is no difference between absolute and relative
// positions. If it refers to a //line directive, a relative position is relative
// to that directive. A position base in turn contains the position at which it
// was introduced in the current file.
type Pos struct {

	f.SetLinesForContent(src)

	// verify position info
	for i, offs := range f.lines {
		got1 := f.PositionFor(f.Pos(offs), false)
		got2 := f.PositionFor(f.Pos(offs), true)
		got3 := f.Position(f.Pos(offs))
		want := Position{filename, offs, i + 1, 1}
		checkPos(t, "1. PositionFor unadjusted", got1, want)
		checkPos(t, "1. PositionFor adjusted", got2, want)
		checkPos(t, "1. Position", got3, want)
	}

		if fdecl, ok := decl.(*ast.FuncDecl); ok {
			ast.Walk(&Visitor{expectation, fset, t}, fdecl.Body)
		}
	}
	for ident, positions := range expectation {
		for _, position := range positions {
			if !position.Visited {
				t.Errorf("Position %d:%d missed for %s ident", position.Line, position.Column, ident)
			}
		}
	}

		// Get the filename, line, and column back via the file set.
		// We get both the relative and absolute position.
		// The relative position is relative to the last line directive.
		// The absolute position is the exact position in the source.
		pos := decl.Pos()
		relPosition := fset.Position(pos)
		absPosition := fset.PositionFor(pos, false)

		// Either a FuncDecl or GenDecl, since we exit on error.
		kind := "func"

func (p position_) String() string {
	if p.line == 0 {
		if p.filename == "" {
			return "<unknown position>"
		}
		return p.filename
	}
	if p.col == 0 {
		return fmt.Sprintf("%s:%d", p.filename, p.line)
	}
	return fmt.Sprintf("%s:%d:%d", p.filename, p.line, p.col)
}

// A PosBase represents the base for relative position information:
// At position pos, the relative position is filename:line:col.