Go: Track whether a type parameter type was declared as part of a receiver by jketema · Pull Request #22178 · github/codeql

jketema · 2026-07-13T10:38:10Z

This is needed for Go 1.27, as generic methods will have type parameter types that are both defined in receivers and on the methods themselves. Tracking this as part of the keyset avoids the dataset check errors that would otherwise occur.

All the needed data is there already in Go 1.26, so target main and not the upgrade branch.

Copilot

Pull request overview

This PR updates the Go extractor + schema to track whether a typeparam row originated from receiver type parameters, avoiding keyset collisions expected with Go 1.27’s generic methods (receiver + method type parameters).

Changes:

Extend the typeparam relation keyset with a new boolean is_from_recv column and plumb it through extractor emission and the QL library API (TypeParamType.isFromReceiver()).
Update the Go extractor’s type-parameter parent tracking to record whether a type parameter came from the receiver vs the method/type declaration.
Add corresponding upgrade/downgrade steps and update the regression test output to include the new column.

Show a summary per file

File	Description
go/ql/test/library-tests/semmle/go/Function/TypeParamType.ql	Test query updated to select `isFromReceiver()` output.
go/ql/test/library-tests/semmle/go/Function/TypeParamType.expected	Expected results updated to include receiver-origin boolean.
go/ql/lib/upgrades/b1341734d6870b105e5c9d168ce7dec25d7f72d0/upgrade.properties	Adds upgrade step for `typeparam` relation.
go/ql/lib/upgrades/b1341734d6870b105e5c9d168ce7dec25d7f72d0/typeparam.ql	Upgrade query populates new boolean column (defaulting to `false`).
go/ql/lib/upgrades/b1341734d6870b105e5c9d168ce7dec25d7f72d0/old.dbscheme	Upgrade metadata: old schema snapshot for this upgrade step.
go/ql/lib/upgrades/b1341734d6870b105e5c9d168ce7dec25d7f72d0/go.dbscheme	Upgrade metadata: new schema snapshot for this upgrade step.
go/ql/lib/semmle/go/Types.qll	QL API updated to expose `isFromReceiver()` from the underlying relation.
go/ql/lib/go.dbscheme.stats	Schema stats updated for the new column.
go/ql/lib/go.dbscheme	`typeparam` relation updated with `is_from_recv` and extended keyset.
go/extractor/trap/trapwriter.go	Adds boolean emission support for TRAP tuples.
go/extractor/extractor.go	Tracks receiver-origin for type parameters; includes it in label + emitted `typeparam` rows.
go/extractor/dbscheme/tables.go	Adds boolean column + keyset change to `TypeParamTable`.
go/extractor/dbscheme/dbscheme.go	Adds `BooleanColumn` helper to define boolean columns.
go/downgrades/5ff5325d274ae4f86defa195577bc7c1370b72fa/upgrade.properties	Adds downgrade step for `typeparam` relation.
go/downgrades/5ff5325d274ae4f86defa195577bc7c1370b72fa/typeparam.ql	Downgrade query drops the new boolean column.
go/downgrades/5ff5325d274ae4f86defa195577bc7c1370b72fa/old.dbscheme	Downgrade metadata: old schema snapshot for this downgrade step.
go/downgrades/5ff5325d274ae4f86defa195577bc7c1370b72fa/go.dbscheme	Downgrade metadata: new schema snapshot for this downgrade step.

Review details

Files reviewed: 17/17 changed files
Comments generated: 2
Review effort level: Low

jketema · 2026-07-13T10:53:12Z

+		for tparam := range typeparams.TypeParams() {
+			setTypeParamParent(tparam, parent, isFromReceiver)
 		}


The VSCode Go extension begs to differ.

I believe that this syntax works correctly in newer versions of go. There would be a compilation error otherwise.

jketema · 2026-07-13T10:53:48Z

+  /** Holds if this type parameter type is declared as part of a receiver */
+  boolean isFromReceiver() { typeparam(this, _, _, _, _, result) }


Update to predicate instead of boolean, which is what I intended to do.

owen-mc

Looks pretty good. Just a few minor comments.

owen-mc · 2026-07-13T20:27:09Z

+	recvTypeParams := funcObj.Type().(*types.Signature).RecvTypeParams()
+	populateTypeParamParents(recvTypeParams, funcObj, true)
+	typeParams := funcObj.Type().(*types.Signature).TypeParams()
+	populateTypeParamParents(typeParams, funcObj, false)


(non-blocking) I personally slightly prefer:

Suggested change

recvTypeParams := funcObj.Type().(*types.Signature).RecvTypeParams()

populateTypeParamParents(recvTypeParams, funcObj, true)

typeParams := funcObj.Type().(*types.Signature).TypeParams()

populateTypeParamParents(typeParams, funcObj, false)

signature := funcObj.Type().(*types.Signature)

populateTypeParamParents(signature.RecvTypeParams(), funcObj, true)

populateTypeParamParents(signature.TypeParams(), funcObj, false)

owen-mc · 2026-07-13T20:35:34Z

+		for tparam := range typeparams.TypeParams() {
+			setTypeParamParent(tparam, parent, isFromReceiver)
 		}


I believe that this syntax works correctly in newer versions of go. There would be a compilation error otherwise.

owen-mc · 2026-07-13T21:28:28Z

+	} else if entry.parent != newobj {
+		log.Fatalf("Parent of type parameter '%s %s' being set to a different value: '%s' vs '%s'", tp.String(), tp.Constraint().String(), entry.parent, newobj)


For completeness, we should also detect the case that entry.isFromReceiver != isFromReceiver and log it somehow. Perhaps the simplest way is to assign newEntry := typeParamParentEntry{newobj, isFromReceiver} before the conditional, then compare entry != newEntry in this conditional and log entry and newEntry instead of entry.parent and newobj.

owen-mc · 2026-07-13T21:29:08Z


-func setTypeParamParent(tp *types.TypeParam, newobj types.Object) {
-	obj, exists := typeParamParent[tp]
+func setTypeParamParent(tp *types.TypeParam, newobj types.Object, isFromReceiver bool) {


(non-blocking) Consider renaming newobj to parent to match the field names of the new struct type.

owen-mc · 2026-07-13T21:46:21Z

+
+from TypeParamType tp, string name, CompositeType bound, TypeParamParentObject parent, int idx
+where typeparam(tp, name, bound, parent, idx)
+select tp, name, bound, parent, idx, false


It's probably fine for isReceiverParent to be incorrect sometimes, but I think we can make sure it's always correct for pre-1.27 code. So, for anyone who always uses an up-to-date version of CodeQL it will always be correct.

Suggested change

from TypeParamType tp, string name, CompositeType bound, TypeParamParentObject parent, int idx

where typeparam(tp, name, bound, parent, idx)

select tp, name, bound, parent, idx, false

// In Go 1.26 and below, a type parameter is from a receiver exactly when its

// parent is a method.

boolean isFromReceiver(TypeParamParentObject parent) {

if methodreceivers(parent, _) then result = true else result = false

}

from TypeParamType tp, string name, CompositeType bound, TypeParamParentObject parent, int idx

select tp, name, bound, parent, idx, isFromReceiver(parent)

jketema added 2 commits July 13, 2026 12:35

Go: Track whether a type parameter was defined as part of a receiver

032636c

Go: Add upgrade and downgrade scripts

37454ab

github-actions Bot added the Go label Jul 13, 2026

Go: Expose new TypeParamType column and use in test

e17508c

jketema force-pushed the jketema/go-recv branch from 1c0f21f to e17508c Compare July 13, 2026 10:42

jketema marked this pull request as ready for review July 13, 2026 10:45

jketema requested a review from a team as a code owner July 13, 2026 10:45

Copilot AI review requested due to automatic review settings July 13, 2026 10:45

jketema requested a review from a team as a code owner July 13, 2026 10:45

jketema mentioned this pull request Jul 13, 2026

Go: Update to 1.27 #22042

Draft

Copilot started reviewing on behalf of jketema July 13, 2026 10:45 View session

jketema added the no-change-note-required This PR does not need a change note label Jul 13, 2026

Go: Fix dowgrade script formatting

9c1f5c9

Copilot AI reviewed Jul 13, 2026

View reviewed changes

Go: Make isFromReceiver and actual predicate

e0f0987

owen-mc reviewed Jul 13, 2026

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Go: Track whether a type parameter type was declared as part of a receiver#22178

Go: Track whether a type parameter type was declared as part of a receiver#22178
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		/** Holds if this type parameter type is declared as part of a receiver */
		boolean isFromReceiver() { typeparam(this, _, _, _, _, result) }

		} else if entry.parent != newobj {
		log.Fatalf("Parent of type parameter '%s %s' being set to a different value: '%s' vs '%s'", tp.String(), tp.Constraint().String(), entry.parent, newobj)

-from TypeParamType tp, string name, CompositeType bound, TypeParamParentObject parent, int idx
-where typeparam(tp, name, bound, parent, idx)
-select tp, name, bound, parent, idx, false
+// In Go 1.26 and below, a type parameter is from a receiver exactly when its
+// parent is a method.
+boolean isFromReceiver(TypeParamParentObject parent) {
+  if methodreceivers(parent, _) then result = true else result = false
+}
+from TypeParamType tp, string name, CompositeType bound, TypeParamParentObject parent, int idx
+select tp, name, bound, parent, idx, isFromReceiver(parent)

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jketema commented Jul 13, 2026 •

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