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cmd/compile/internal/types2: review of stmt.go

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The changes between (equivalent, and reviewed) go/types/stmt.go
and stmt.go can be seen by comparing patchset 1 and 2. The actual
changes are removing the "// UNREVIEWED" marker, and minor adjustments
to get the code slightly closer to go/types/stmt.go.

The primary differences compared to go/types are:
- use of syntax rather than go/ast package, with significant
  differences in the representation of switch and select statements,
  range clauses of for statements, and inc/dec statements.
- no reporting of error codes
- use or error_ for collecting addition error information

Change-Id: I4409f62ecafd0653e4c8ef087c2580d8f0544efc
Reviewed-on: https://go-review.googlesource.com/c/go/+/305576
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
This commit is contained in:
Robert Griesemer 2021-03-29 13:36:53 -07:00
parent a1e4657d5a
commit 93dcaba119
1 changed files with 13 additions and 12 deletions
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25
src/cmd/compile/internal/types2/stmt.go
View file

@ -1,4 +1,3 @@
// UNREVIEWED
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
@ -265,7 +264,7 @@ L:
}
}
func (check *Checker) caseTypes(x *operand, xtyp *Interface, types []syntax.Expr, seen map[Type]syntax.Pos) (T Type) {
func (check *Checker) caseTypes(x *operand, xtyp *Interface, types []syntax.Expr, seen map[Type]syntax.Expr) (T Type) {
L:
for _, e := range types {
T = check.typOrNil(e)
@ -277,7 +276,7 @@ L:
}
// look for duplicate types
// (quadratic algorithm, but type switches tend to be reasonably small)
for t, pos := range seen {
for t, other := range seen {
if T == nil && t == nil || T != nil && t != nil && check.identical(T, t) {
// talk about "case" rather than "type" because of nil case
Ts := "nil"
@ -286,12 +285,12 @@ L:
}
var err error_
err.errorf(e, "duplicate case %s in type switch", Ts)
err.errorf(pos, "previous case")
err.errorf(other, "previous case")
check.report(&err)
continue L
}
}
seen[T] = e.Pos()
seen[T] = e
if T != nil {
check.typeAssertion(e.Pos(), x, xtyp, T)
}
@ -409,11 +408,6 @@ func (check *Checker) stmt(ctxt stmtContext, s syntax.Stmt) {
check.binary(&x, nil, lhs[0], rhs[0], s.Op)
check.assignVar(lhs[0], &x)
// case *syntax.GoStmt:
// check.suspendedCall("go", s.Call)
// case *syntax.DeferStmt:
// check.suspendedCall("defer", s.Call)
case *syntax.CallStmt:
// TODO(gri) get rid of this conversion to string
kind := "go"
@ -686,6 +680,10 @@ func (check *Checker) typeSwitchStmt(inner stmtContext, s *syntax.SwitchStmt, gu
if x.mode == invalid {
return
}
// Caution: We're not using asInterface here because we don't want
// to switch on a suitably constrained type parameter (for
// now).
// TODO(gri) Need to revisit this.
xtyp, _ := under(x.typ).(*Interface)
if xtyp == nil {
check.errorf(&x, "%s is not an interface type", &x)
@ -695,8 +693,8 @@ func (check *Checker) typeSwitchStmt(inner stmtContext, s *syntax.SwitchStmt, gu
check.multipleSwitchDefaults(s.Body)
var lhsVars []*Var // list of implicitly declared lhs variables
seen := make(map[Type]syntax.Pos) // map of seen types to positions
var lhsVars []*Var // list of implicitly declared lhs variables
seen := make(map[Type]syntax.Expr) // map of seen types to positions
for i, clause := range s.Body {
if clause == nil {
check.error(s, invalidAST+"incorrect type switch case")
@ -739,6 +737,9 @@ func (check *Checker) typeSwitchStmt(inner stmtContext, s *syntax.SwitchStmt, gu
}
// If lhs exists, we must have at least one lhs variable that was used.
// (We can't use check.usage because that only looks at one scope; and
// we don't want to use the same variable for all scopes and change the
// variable type underfoot.)
if lhs != nil {
var used bool
for _, v := range lhsVars {