cmd/compile: resolve dictionaries/shape methods in markInlBody, if needed

Issue #50552 is due to a problem with my recent improvement in the
interaction between generics and inlining. In markInlBody(), we now mark
dictionaries and shape methods for export, so they will be available for
any package that inlines the current inlineable function. But we need to
make sure that the dictionary and method symbols have actually been
resolved into Nodes (looked up in the import data), if they are not
already defined, so we can then mark them for export.

Improved header comment on Resolve().

Fixes #50552

Change-Id: I89e52d39d3b9894591d2ad6eb3a8ed3bb5f1e0a0
Reviewed-on: https://go-review.googlesource.com/c/go/+/377714
Reviewed-by: Keith Randall <khr@golang.org>
Trust: Dan Scales <danscales@google.com>

1 files changed, 15 insertions, 5 deletions

diff --git a/src/cmd/compile/internal/typecheck/crawler.go b/src/cmd/compile/internal/typecheck/crawler.go
index cdb1c46509..87dc5165fd 100644
--- a/src/cmd/compile/internal/typecheck/crawler.go
+++ b/src/cmd/compile/internal/typecheck/crawler.go
@@ -8,6 +8,7 @@ import (
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/types"
+	"cmd/internal/src"
 )
 
 // crawlExports crawls the type/object graph rooted at the given list of exported
@@ -241,11 +242,12 @@ func (p *crawler) markInlBody(n *ir.Name) {
 			if t.IsFullyInstantiated() && !t.HasShape() && !t.IsInterface() && t.Methods().Len() > 0 {
 				// For any fully-instantiated type, the relevant
 				// dictionaries and shape instantiations will have
-				// already been created. Make sure that they are
-				// exported, so that any other package that inlines
-				// this function will have them available for import,
-				// and so will not need another round of method and
-				// dictionary instantiation after inlining.
+				// already been created or are in the import data.
+				// Make sure that they are exported, so that any
+				// other package that inlines this function will have
+				// them available for import, and so will not need
+				// another round of method and dictionary
+				// instantiation after inlining.
 				baseType := t.OrigSym().Def.(*ir.Name).Type()
 				shapes := make([]*types.Type, len(t.RParams()))
 				for i, t1 := range t.RParams() {
@@ -254,8 +256,16 @@ func (p *crawler) markInlBody(n *ir.Name) {
 				for j := range t.Methods().Slice() {
 					baseNname := baseType.Methods().Slice()[j].Nname.(*ir.Name)
 					dictsym := MakeDictSym(baseNname.Sym(), t.RParams(), true)
+					if dictsym.Def == nil {
+						in := Resolve(ir.NewIdent(src.NoXPos, dictsym))
+						dictsym = in.Sym()
+					}
 					Export(dictsym.Def.(*ir.Name))
 					methsym := MakeFuncInstSym(baseNname.Sym(), shapes, false, true)
+					if methsym.Def == nil {
+						in := Resolve(ir.NewIdent(src.NoXPos, methsym))
+						methsym = in.Sym()
+					}
 					methNode := methsym.Def.(*ir.Name)
 					Export(methNode)
 					if HaveInlineBody(methNode.Func) {