cmd/link: remove importcycles function

The importcycles method has not been useful since April 2016 when a large code deletion was performed.

The compiler itself provides some protection against import cycles, and the linker does import cycle detection in linksetup -> postorder.

For #57400

Change-Id: I3095bdb3f16a82ba25681bf4a20ceaa3c9613921
GitHub-Last-Rev: 87a46153b136db67675874ffe46e5881b9c756ce
GitHub-Pull-Request: golang/go#57462
Reviewed-on: https://go-review.googlesource.com/c/go/+/459475
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>

2 files changed, 0 insertions, 47 deletions

diff --git a/src/cmd/link/internal/ld/go.go b/src/cmd/link/internal/ld/go.go
index 9dfb0f756e..ef73924914 100644
--- a/src/cmd/link/internal/ld/go.go
+++ b/src/cmd/link/internal/ld/go.go
@@ -452,48 +452,3 @@ func (ctxt *Link) addexport() {
 		adddynlib(ctxt, lib)
 	}
 }
-
-type Pkg struct {
-	mark    bool
-	checked bool
-	path    string
-	impby   []*Pkg
-}
-
-var pkgall []*Pkg
-
-func (p *Pkg) cycle() *Pkg {
-	if p.checked {
-		return nil
-	}
-
-	if p.mark {
-		nerrors++
-		fmt.Printf("import cycle:\n")
-		fmt.Printf("\t%s\n", p.path)
-		return p
-	}
-
-	p.mark = true
-	for _, q := range p.impby {
-		if bad := q.cycle(); bad != nil {
-			p.mark = false
-			p.checked = true
-			fmt.Printf("\timports %s\n", p.path)
-			if bad == p {
-				return nil
-			}
-			return bad
-		}
-	}
-
-	p.checked = true
-	p.mark = false
-	return nil
-}
-
-func importcycles() {
-	for _, p := range pkgall {
-		p.cycle()
-	}
-}
diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index c0730179db..22c764ada5 100644
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -646,8 +646,6 @@ func (ctxt *Link) loadlib() {
 	// We've loaded all the code now.
 	ctxt.Loaded = true
 
-	importcycles()
-
 	strictDupMsgCount = ctxt.loader.NStrictDupMsgs()
 }