cmd/compile/internal/types2: use []*TypeParam rather than []*TypeName for type param lists

This is a port of CL 343932 from go/types, with the necessary adjustments
to the compiler.

This change improves type safety slightly, avoids many internal type
assertions, and simplifies some code paths.

Change-Id: Ie9c4734814f49cd248927152d7b3264d3578428c
Reviewed-on: https://go-review.googlesource.com/c/go/+/344614
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Dan Scales <danscales@google.com>

5 files changed, 14 insertions, 14 deletions

diff --git a/src/cmd/compile/internal/noder/decl.go b/src/cmd/compile/internal/noder/decl.go
index 6b55ce1453..ffcfc103a6 100644
--- a/src/cmd/compile/internal/noder/decl.go
+++ b/src/cmd/compile/internal/noder/decl.go
@@ -191,7 +191,7 @@ func (g *irgen) typeDecl(out *ir.Nodes, decl *syntax.TypeDecl) {
 	if n := tparams.Len(); n > 0 {
 		rparams := make([]*types.Type, n)
 		for i := range rparams {
-			rparams[i] = g.typ(tparams.At(i).Type())
+			rparams[i] = g.typ(tparams.At(i))
 		}
 		// This will set hasTParam flag if any rparams are not concrete types.
 		ntyp.SetRParams(rparams)
diff --git a/src/cmd/compile/internal/noder/reader2.go b/src/cmd/compile/internal/noder/reader2.go
index e72a6737ed..8f3f0a50e9 100644
--- a/src/cmd/compile/internal/noder/reader2.go
+++ b/src/cmd/compile/internal/noder/reader2.go
@@ -396,7 +396,7 @@ func (pr *pkgReader2) objIdx(idx int) (*types2.Package, string) {
 		case objType:
 			pos := r.pos()
 
-			return types2.NewTypeNameLazy(pos, objPkg, objName, func(named *types2.Named) (tparams []*types2.TypeName, underlying types2.Type, methods []*types2.Func) {
+			return types2.NewTypeNameLazy(pos, objPkg, objName, func(named *types2.Named) (tparams []*types2.TypeParam, underlying types2.Type, methods []*types2.Func) {
 				tparams = r.typeParamNames()
 
 				// TODO(mdempsky): Rewrite receiver types to underlying is an
@@ -453,7 +453,7 @@ func (pr *pkgReader2) objDictIdx(idx int) *reader2Dict {
 	return &dict
 }
 
-func (r *reader2) typeParamNames() []*types2.TypeName {
+func (r *reader2) typeParamNames() []*types2.TypeParam {
 	r.sync(syncTypeParamNames)
 
 	// Note: This code assumes it only processes objects without
@@ -470,21 +470,20 @@ func (r *reader2) typeParamNames() []*types2.TypeName {
 	// create all the TypeNames and TypeParams, then we construct and
 	// set the bound type.
 
-	names := make([]*types2.TypeName, len(r.dict.bounds))
 	r.dict.tparams = make([]*types2.TypeParam, len(r.dict.bounds))
 	for i := range r.dict.bounds {
 		pos := r.pos()
 		pkg, name := r.localIdent()
 
-		names[i] = types2.NewTypeName(pos, pkg, name, nil)
-		r.dict.tparams[i] = r.p.check.NewTypeParam(names[i], nil)
+		tname := types2.NewTypeName(pos, pkg, name, nil)
+		r.dict.tparams[i] = r.p.check.NewTypeParam(tname, nil)
 	}
 
 	for i, bound := range r.dict.bounds {
 		r.dict.tparams[i].SetConstraint(r.p.typIdx(bound, r.dict))
 	}
 
-	return names
+	return r.dict.tparams
 }
 
 func (r *reader2) method() *types2.Func {
diff --git a/src/cmd/compile/internal/noder/syncmarker_string.go b/src/cmd/compile/internal/noder/syncmarker_string.go
index 14747b7c10..655cafc950 100644
--- a/src/cmd/compile/internal/noder/syncmarker_string.go
+++ b/src/cmd/compile/internal/noder/syncmarker_string.go
@@ -140,11 +140,12 @@ func _() {
 	_ = x[syncTypeParamNames-130]
 	_ = x[syncTypeParamBounds-131]
 	_ = x[syncImplicitTypes-132]
+	_ = x[syncObjectName-133]
 }
 
-const _syncMarker_name = "NodeBoolInt64Uint64StringPosPkgSymSelectorKindTypeTypePkgSignatureParamOpObjectExprStmtDeclConstDeclFuncDeclTypeDeclVarDeclPragmaValueEOFMethodFuncBodyUseUseObjObjectIdxTypeIdxBOFEntryOpenScopeCloseScopeGlobalLocalDefineDefLocalUseLocalDefGlobalUseGlobalTypeParamsUseLabelDefLabelFuncLitCommonFuncBodyRefLinksymExtHackSetlinenoNameImportDeclDeclNamesDeclNameExprListExprsWrapnameTypeExprTypeExprOrNilChanDirParamsCloseAnotherScopeSumUnOpBinOpStructTypeInterfaceTypePacknameEmbeddedStmtsStmtsFallStmtFallBlockStmtIfStmtForStmtSwitchStmtRangeStmtCaseClauseCommClauseSelectStmtDeclsLabeledStmtCompLit1234NDefImplicitUseNameUseObjLocalAddLocalBothSignatureSetUnderlyingLinknameStmt1StmtsEndDeclareTopDeclsTopConstDeclTopFuncDeclTopTypeDeclTopVarDeclObject1AddBodyLabelFuncExtMethExtOptLabelScalarStmtDeclsDeclLocalObjLocalObjLocal1DeclareLocalPublicPrivateRelocsRelocUseRelocVarExtPkgDefTypeExtValCodeObjPosBaseLocalIdentTypeParamNamesTypeParamBoundsImplicitTypes"
+const _syncMarker_name = "NodeBoolInt64Uint64StringPosPkgSymSelectorKindTypeTypePkgSignatureParamOpObjectExprStmtDeclConstDeclFuncDeclTypeDeclVarDeclPragmaValueEOFMethodFuncBodyUseUseObjObjectIdxTypeIdxBOFEntryOpenScopeCloseScopeGlobalLocalDefineDefLocalUseLocalDefGlobalUseGlobalTypeParamsUseLabelDefLabelFuncLitCommonFuncBodyRefLinksymExtHackSetlinenoNameImportDeclDeclNamesDeclNameExprListExprsWrapnameTypeExprTypeExprOrNilChanDirParamsCloseAnotherScopeSumUnOpBinOpStructTypeInterfaceTypePacknameEmbeddedStmtsStmtsFallStmtFallBlockStmtIfStmtForStmtSwitchStmtRangeStmtCaseClauseCommClauseSelectStmtDeclsLabeledStmtCompLit1234NDefImplicitUseNameUseObjLocalAddLocalBothSignatureSetUnderlyingLinknameStmt1StmtsEndDeclareTopDeclsTopConstDeclTopFuncDeclTopTypeDeclTopVarDeclObject1AddBodyLabelFuncExtMethExtOptLabelScalarStmtDeclsDeclLocalObjLocalObjLocal1DeclareLocalPublicPrivateRelocsRelocUseRelocVarExtPkgDefTypeExtValCodeObjPosBaseLocalIdentTypeParamNamesTypeParamBoundsImplicitTypesObjectName"
 
-var _syncMarker_index = [...]uint16{0, 4, 8, 13, 19, 25, 28, 31, 34, 42, 46, 50, 57, 66, 71, 73, 79, 83, 87, 91, 100, 108, 116, 123, 129, 134, 137, 143, 151, 154, 160, 169, 176, 179, 184, 193, 203, 209, 214, 220, 228, 236, 245, 254, 264, 272, 280, 287, 297, 304, 314, 318, 327, 331, 341, 350, 358, 366, 371, 379, 387, 400, 407, 413, 430, 433, 437, 442, 452, 465, 473, 481, 486, 495, 503, 512, 518, 525, 535, 544, 554, 564, 574, 579, 590, 597, 598, 599, 600, 601, 602, 613, 620, 631, 639, 652, 665, 673, 678, 686, 693, 701, 713, 724, 735, 745, 752, 759, 764, 771, 778, 786, 792, 801, 810, 818, 827, 839, 845, 852, 858, 863, 871, 877, 883, 890, 893, 900, 907, 917, 931, 946, 959}
+var _syncMarker_index = [...]uint16{0, 4, 8, 13, 19, 25, 28, 31, 34, 42, 46, 50, 57, 66, 71, 73, 79, 83, 87, 91, 100, 108, 116, 123, 129, 134, 137, 143, 151, 154, 160, 169, 176, 179, 184, 193, 203, 209, 214, 220, 228, 236, 245, 254, 264, 272, 280, 287, 297, 304, 314, 318, 327, 331, 341, 350, 358, 366, 371, 379, 387, 400, 407, 413, 430, 433, 437, 442, 452, 465, 473, 481, 486, 495, 503, 512, 518, 525, 535, 544, 554, 564, 574, 579, 590, 597, 598, 599, 600, 601, 602, 613, 620, 631, 639, 652, 665, 673, 678, 686, 693, 701, 713, 724, 735, 745, 752, 759, 764, 771, 778, 786, 792, 801, 810, 818, 827, 839, 845, 852, 858, 863, 871, 877, 883, 890, 893, 900, 907, 917, 931, 946, 959, 969}
 
 func (i syncMarker) String() string {
 	i -= 1
diff --git a/src/cmd/compile/internal/noder/types.go b/src/cmd/compile/internal/noder/types.go
index 8d596e599e..dd1fdcf96b 100644
--- a/src/cmd/compile/internal/noder/types.go
+++ b/src/cmd/compile/internal/noder/types.go
@@ -306,7 +306,7 @@ func (g *irgen) fillinMethods(typ *types2.Named, ntyp *types.Type) {
 					rparams := types2.AsSignature(m.Type()).RParams()
 					tparams := make([]*types.Type, rparams.Len())
 					for i := range tparams {
-						tparams[i] = g.typ1(rparams.At(i).Type())
+						tparams[i] = g.typ1(rparams.At(i))
 					}
 					assert(len(tparams) == len(targs))
 					ts := typecheck.Tsubster{
@@ -338,7 +338,7 @@ func (g *irgen) signature(recv *types.Field, sig *types2.Signature) *types.Type
 	tparams2 := sig.TParams()
 	tparams := make([]*types.Field, tparams2.Len())
 	for i := range tparams {
-		tp := tparams2.At(i)
+		tp := tparams2.At(i).Obj()
 		tparams[i] = types.NewField(g.pos(tp), g.sym(tp), g.typ1(tp.Type()))
 	}
 
diff --git a/src/cmd/compile/internal/noder/writer.go b/src/cmd/compile/internal/noder/writer.go
index a33b24e50c..02df9a43de 100644
--- a/src/cmd/compile/internal/noder/writer.go
+++ b/src/cmd/compile/internal/noder/writer.go
@@ -618,7 +618,7 @@ func (w *writer) objDict(obj types2.Object, dict *writerDict) {
 	ntparams := tparams.Len()
 	w.len(ntparams)
 	for i := 0; i < ntparams; i++ {
-		w.typ(tparams.At(i).Type().(*types2.TypeParam).Constraint())
+		w.typ(tparams.At(i).Constraint())
 	}
 
 	nderived := len(dict.derived)
@@ -647,7 +647,7 @@ func (w *writer) typeParamNames(tparams *types2.TParamList) {
 
 	ntparams := tparams.Len()
 	for i := 0; i < ntparams; i++ {
-		tparam := tparams.At(i)
+		tparam := tparams.At(i).Obj()
 		w.pos(tparam)
 		w.localIdent(tparam)
 	}
@@ -1479,7 +1479,7 @@ func (c *declCollector) withTParams(obj types2.Object) *declCollector {
 	copy := *c
 	copy.implicits = copy.implicits[:len(copy.implicits):len(copy.implicits)]
 	for i := 0; i < n; i++ {
-		copy.implicits = append(copy.implicits, tparams.At(i))
+		copy.implicits = append(copy.implicits, tparams.At(i).Obj())
 	}
 	return &copy
 }