cmd/compile: do branch/label checks only once
The previous change implemented the missing fallthrough checking
in the parser. Therefore we can now disable the duplicate check
in the type checker:
- rename (types2.Config.)IngoreLabels to IgnoreBranches to more
accurately reflect its functionality
- now also ignore break/continue/fallthroughs, not just labels
The IgnoreBranches flag only exists for types2, for use with
the compiler. There's no need to port this code to go/types.
Note: An alternative (and perhaps better) approach would be
to not use the the parser's CheckBranches mode and instead
enable (i.e. not disable) the branch/label checking in the
type checker. However, this requires a bit more work because
the type checker's error messages about goto's jumping over
variables don't have access to the variable names, which are
desired in the error messages.
Fixes #51456.
Change-Id: Ib2e71e811d4e84e4895b729646e879fd43b12dcd
Reviewed-on: https://go-review.googlesource.com/c/go/+/414135
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
diff --git a/src/cmd/compile/internal/noder/irgen.go b/src/cmd/compile/internal/noder/irgen.go
index 628c0f5..e45a204 100644
--- a/src/cmd/compile/internal/noder/irgen.go
+++ b/src/cmd/compile/internal/noder/irgen.go
@@ -41,7 +41,7 @@
conf := types2.Config{
Context: ctxt,
GoVersion: base.Flag.Lang,
- IgnoreLabels: true, // parser already checked via syntax.CheckBranches mode
+ IgnoreBranchErrors: true, // parser already checked via syntax.CheckBranches mode
CompilerErrorMessages: true, // use error strings matching existing compiler errors
Error: func(err error) {
terr := err.(types2.Error)
diff --git a/src/cmd/compile/internal/noder/noder.go b/src/cmd/compile/internal/noder/noder.go
index c4c2db5..15b1bf7 100644
--- a/src/cmd/compile/internal/noder/noder.go
+++ b/src/cmd/compile/internal/noder/noder.go
@@ -27,8 +27,6 @@
func LoadPackage(filenames []string) {
base.Timer.Start("fe", "parse")
- mode := syntax.CheckBranches
-
// Limit the number of simultaneously open files.
sem := make(chan struct{}, runtime.GOMAXPROCS(0)+10)
@@ -58,7 +56,7 @@
}
defer f.Close()
- p.file, _ = syntax.Parse(fbase, f, p.error, p.pragma, mode) // errors are tracked via p.error
+ p.file, _ = syntax.Parse(fbase, f, p.error, p.pragma, syntax.CheckBranches) // errors are tracked via p.error
}()
}
}()
diff --git a/src/cmd/compile/internal/types2/api.go b/src/cmd/compile/internal/types2/api.go
index a739b11..a22ea5d 100644
--- a/src/cmd/compile/internal/types2/api.go
+++ b/src/cmd/compile/internal/types2/api.go
@@ -128,9 +128,8 @@
// Do not use casually!
FakeImportC bool
- // If IgnoreLabels is set, correct label use is not checked.
- // TODO(gri) Consolidate label checking and remove this flag.
- IgnoreLabels bool
+ // If IgnoreBranchErrors is set, branch/label errors are ignored.
+ IgnoreBranchErrors bool
// If CompilerErrorMessages is set, errors are reported using
// cmd/compile error strings to match $GOROOT/test errors.
diff --git a/src/cmd/compile/internal/types2/stmt.go b/src/cmd/compile/internal/types2/stmt.go
index e00f73c..74d4164 100644
--- a/src/cmd/compile/internal/types2/stmt.go
+++ b/src/cmd/compile/internal/types2/stmt.go
@@ -41,7 +41,7 @@
check.stmtList(0, body.List)
- if check.hasLabel && !check.conf.IgnoreLabels {
+ if check.hasLabel && !check.conf.IgnoreBranchErrors {
check.labels(body)
}
@@ -504,22 +504,17 @@
check.hasLabel = true
break // checked in 2nd pass (check.labels)
}
+ if check.conf.IgnoreBranchErrors {
+ break
+ }
switch s.Tok {
case syntax.Break:
if ctxt&breakOk == 0 {
- if check.conf.CompilerErrorMessages {
- check.error(s, "break is not in a loop, switch, or select statement")
- } else {
- check.error(s, "break not in for, switch, or select statement")
- }
+ check.error(s, "break not in for, switch, or select statement")
}
case syntax.Continue:
if ctxt&continueOk == 0 {
- if check.conf.CompilerErrorMessages {
- check.error(s, "continue is not in a loop")
- } else {
- check.error(s, "continue not in for statement")
- }
+ check.error(s, "continue not in for statement")
}
case syntax.Fallthrough:
if ctxt&fallthroughOk == 0 {
