[dev.typeparams] cmd/compile: fixing import of comm clauses/closures in generic functions

Improvements:
 - Fix export/import of the default case of a select statement (was not
   dealing with nil Comm case)
 - Set properly the name of closure functions in imported generic
   functions

Added new test exporting/importing a reasonably large channel package,
chansimp.go.

Change-Id: If2ee12bd749e5df415f48ec4b629a2fa68a79dcb
Reviewed-on: https://go-review.googlesource.com/c/go/+/321734
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Trust: Dan Scales <danscales@google.com>

1 files changed, 13 insertions, 1 deletions

diff --git a/src/cmd/compile/internal/typecheck/iimport.go b/src/cmd/compile/internal/typecheck/iimport.go
index 39b5ab09da..966e865630 100644
--- a/src/cmd/compile/internal/typecheck/iimport.go
+++ b/src/cmd/compile/internal/typecheck/iimport.go
@@ -1121,7 +1121,13 @@ func (r *importReader) caseList(switchExpr ir.Node) []*ir.CaseClause {
 func (r *importReader) commList() []*ir.CommClause {
 	cases := make([]*ir.CommClause, r.uint64())
 	for i := range cases {
-		cases[i] = ir.NewCommStmt(r.pos(), r.node(), r.stmtList())
+		pos := r.pos()
+		defaultCase := r.bool()
+		var comm ir.Node
+		if !defaultCase {
+			comm = r.node()
+		}
+		cases[i] = ir.NewCommStmt(pos, comm, r.stmtList())
 	}
 	return cases
 }
@@ -1257,6 +1263,12 @@ func (r *importReader) node() ir.Node {
 		if go117ExportTypes {
 			clo.SetType(typ)
 		}
+		if r.curfn.Type().HasTParam() {
+			// Generic functions aren't inlined, so give the closure a
+			// function name now, which is then available for use
+			// (after appending the type args) for each stenciling.
+			fn.Nname.SetSym(ClosureName(r.curfn))
+		}
 
 		return clo