Add build tag to build without deprecated global name validation scheme

.github/workflows/go.yml

@@ -34,17 +34,18 @@ jobs:
             echo "supported_versions=$matrix" >> $GITHUB_OUTPUT
 
   test:
-    name: Tests (${{ matrix.go_version }})
+    name: Tests (${{ matrix.go_version }}, ${{ matrix.validation_scheme }} name validation scheme)
     runs-on: ubuntu-latest
     needs: supportedVersions
     # Set fail-fast to false to ensure all Go versions are tested regardless of failures
     strategy:
       fail-fast: false
       matrix:
         go_version: ${{ fromJSON(needs.supportedVersions.outputs.supported_versions) }}
+        validation_scheme: ["global", "local"]
     # Define concurrency at the job level for matrix jobs
     concurrency:
-      group: ${{ github.workflow }}-test-${{ matrix.go_version }}-${{ (github.event.pull_request && github.event.pull_request.number) || github.ref || github.run_id }}
+      group: ${{ github.workflow }}-test-${{ matrix.go_version }}-${{ matrix.validation_scheme }}-${{ (github.event.pull_request && github.event.pull_request.number) || github.ref || github.run_id }}
       cancel-in-progress: true
 
     steps:
@@ -62,7 +63,8 @@ jobs:
         run: make check_license test
         env:
           CI: true
+          GOOPTS: ${{ matrix.validation_scheme == 'local' && '-tags=localvalidationscheme' || '' }}
 
       - name: Run style and unused
-        if: ${{ matrix.go_version == '1.22' }}
+        if: ${{ matrix.go_version == '1.22' && matrix.validation_scheme == 'global' }}
         run: make style unused

examples/exemplars/main.go

@@ -23,6 +23,8 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/prometheus/common/model"
+
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/collectors"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
@@ -49,8 +51,11 @@ func main() {
 		for {
 			// Record fictional latency.
 			now := time.Now()
-			requestDurations.(prometheus.ExemplarObserver).ObserveWithExemplar(
-				time.Since(now).Seconds(), prometheus.Labels{"dummyID": strconv.Itoa(rand.Intn(100000))},
+			observeWithExemplar(
+				requestDurations.(prometheus.ExemplarObserver),
+				time.Since(now).Seconds(),
+				prometheus.Labels{"dummyID": strconv.Itoa(rand.Intn(100000))},
+				model.UTF8Validation,
 			)
 			time.Sleep(600 * time.Millisecond)
 		}

examples/exemplars/main_globalvalidationscheme.go

@@ -0,0 +1,26 @@
+// Copyright 2025 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !localvalidationscheme
+
+package main
+
+import (
+	"github.com/prometheus/common/model"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func observeWithExemplar(obs prometheus.ExemplarObserver, val float64, labels prometheus.Labels, _ model.ValidationScheme) {
+	obs.ObserveWithExemplar(val, labels)
+}

examples/exemplars/main_localvalidationscheme.go

@@ -0,0 +1,26 @@
+// Copyright 2025 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build localvalidationscheme
+
+package main
+
+import (
+	"github.com/prometheus/common/model"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func observeWithExemplar(obs prometheus.ExemplarObserver, val float64, labels prometheus.Labels, scheme model.ValidationScheme) {
+	obs.ObserveWithExemplar(val, labels, scheme)
+}

examples/random/main.go

@@ -25,6 +25,8 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/prometheus/common/model"
+
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/collectors"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
@@ -115,8 +117,11 @@ func main() {
 			// already know that rpcDurationsHistogram implements
 			// the ExemplarObserver interface and thus don't need to
 			// check the outcome of the type assertion.
-			m.rpcDurationsHistogram.(prometheus.ExemplarObserver).ObserveWithExemplar(
-				v, prometheus.Labels{"dummyID": strconv.Itoa(rand.Intn(100000))},
+			observeWithExemplar(
+				m.rpcDurationsHistogram.(prometheus.ExemplarObserver),
+				v,
+				prometheus.Labels{"dummyID": strconv.Itoa(rand.Intn(100000))},
+				model.UTF8Validation,
 			)
 			time.Sleep(time.Duration(75*oscillationFactor()) * time.Millisecond)
 		}

examples/random/main_globalvalidationscheme.go

@@ -0,0 +1,26 @@
+// Copyright 2025 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !localvalidationscheme
+
+package main
+
+import (
+	"github.com/prometheus/common/model"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func observeWithExemplar(obs prometheus.ExemplarObserver, val float64, labels prometheus.Labels, _ model.ValidationScheme) {
+	obs.ObserveWithExemplar(val, labels)
+}

examples/random/main_localvalidationscheme.go

@@ -0,0 +1,26 @@
+// Copyright 2025 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build localvalidationscheme
+
+package main
+
+import (
+	"github.com/prometheus/common/model"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func observeWithExemplar(obs prometheus.ExemplarObserver, val float64, labels prometheus.Labels, scheme model.ValidationScheme) {
+	obs.ObserveWithExemplar(val, labels, scheme)
+}

go.mod

@@ -10,7 +10,7 @@ require (
 	github.com/klauspost/compress v1.18.0
 	github.com/kylelemons/godebug v1.1.0
 	github.com/prometheus/client_model v0.6.2
-	github.com/prometheus/common v0.65.0
+	github.com/prometheus/common v0.65.1-0.20250714091050-c6ae72fb63e9
 	github.com/prometheus/procfs v0.16.1
 	go.uber.org/goleak v1.3.0
 	golang.org/x/sys v0.33.0
@@ -24,9 +24,9 @@ require (
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f // indirect
-	golang.org/x/net v0.40.0 // indirect
+	golang.org/x/net v0.41.0 // indirect
 	golang.org/x/oauth2 v0.30.0 // indirect
-	golang.org/x/text v0.25.0 // indirect
+	golang.org/x/text v0.26.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 )
 

go.sum

@@ -35,8 +35,8 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prometheus/client_model v0.6.2 h1:oBsgwpGs7iVziMvrGhE53c/GrLUsZdHnqNwqPLxwZyk=
 github.com/prometheus/client_model v0.6.2/go.mod h1:y3m2F6Gdpfy6Ut/GBsUqTWZqCUvMVzSfMLjcu6wAwpE=
-github.com/prometheus/common v0.65.0 h1:QDwzd+G1twt//Kwj/Ww6E9FQq1iVMmODnILtW1t2VzE=
-github.com/prometheus/common v0.65.0/go.mod h1:0gZns+BLRQ3V6NdaerOhMbwwRbNh9hkGINtQAsP5GS8=
+github.com/prometheus/common v0.65.1-0.20250714091050-c6ae72fb63e9 h1:W+mk95PFPPi5NOzr2MtiGe7BXlHmsxs7UESIGsW5S08=
+github.com/prometheus/common v0.65.1-0.20250714091050-c6ae72fb63e9/go.mod h1:41VB7D5p4TG2i2w5P4G62ofoS2mVyeTQ9QIAKYE60TE=
 github.com/prometheus/procfs v0.16.1 h1:hZ15bTNuirocR6u0JZ6BAHHmwS1p8B4P6MRqxtzMyRg=
 github.com/prometheus/procfs v0.16.1/go.mod h1:teAbpZRB1iIAJYREa1LsoWUXykVXA1KlTmWl8x/U+Is=
 github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
@@ -48,14 +48,14 @@ github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOf
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
 go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
-golang.org/x/net v0.40.0 h1:79Xs7wF06Gbdcg4kdCCIQArK11Z1hr5POQ6+fIYHNuY=
-golang.org/x/net v0.40.0/go.mod h1:y0hY0exeL2Pku80/zKK7tpntoX23cqL3Oa6njdgRtds=
+golang.org/x/net v0.41.0 h1:vBTly1HeNPEn3wtREYfy4GZ/NECgw2Cnl+nK6Nz3uvw=
+golang.org/x/net v0.41.0/go.mod h1:B/K4NNqkfmg07DQYrbwvSluqCJOOXwUjeb/5lOisjbA=
 golang.org/x/oauth2 v0.30.0 h1:dnDm7JmhM45NNpd8FDDeLhK6FwqbOf4MLCM9zb1BOHI=
 golang.org/x/oauth2 v0.30.0/go.mod h1:B++QgG3ZKulg6sRPGD/mqlHQs5rB3Ml9erfeDY7xKlU=
 golang.org/x/sys v0.33.0 h1:q3i8TbbEz+JRD9ywIRlyRAQbM0qF7hu24q3teo2hbuw=
 golang.org/x/sys v0.33.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
-golang.org/x/text v0.25.0 h1:qVyWApTSYLk/drJRO5mDlNYskwQznZmkpV2c8q9zls4=
-golang.org/x/text v0.25.0/go.mod h1:WEdwpYrmk1qmdHvhkSTNPm3app7v4rsT8F2UD6+VHIA=
+golang.org/x/text v0.26.0 h1:P42AVeLghgTYr4+xUnTRKDMqpar+PtX7KWuNQL21L8M=
+golang.org/x/text v0.26.0/go.mod h1:QK15LZJUUQVJxhz7wXgxSy/CJaTFjd0G+YLonydOVQA=
 google.golang.org/protobuf v1.36.6 h1:z1NpPI8ku2WgiWnf+t9wTPsn6eP1L7ksHUlkfLvd9xY=
 google.golang.org/protobuf v1.36.6/go.mod h1:jduwjTPXsFjZGTmRluh+L6NjiWu7pchiJ2/5YcXBHnY=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

prometheus/counter.go

@@ -20,6 +20,7 @@ import (
 	"time"
 
 	dto "github.com/prometheus/client_model/go"
+	"github.com/prometheus/common/model"
 	"google.golang.org/protobuf/types/known/timestamppb"
 )
 
@@ -44,19 +45,6 @@ type Counter interface {
 	Add(float64)
 }
 
-// ExemplarAdder is implemented by Counters that offer the option of adding a
-// value to the Counter together with an exemplar. Its AddWithExemplar method
-// works like the Add method of the Counter interface but also replaces the
-// currently saved exemplar (if any) with a new one, created from the provided
-// value, the current time as timestamp, and the provided labels. Empty Labels
-// will lead to a valid (label-less) exemplar. But if Labels is nil, the current
-// exemplar is left in place. AddWithExemplar panics if the value is < 0, if any
-// of the provided labels are invalid, or if the provided labels contain more
-// than 128 runes in total.
-type ExemplarAdder interface {
-	AddWithExemplar(value float64, exemplar Labels)
-}
-
 // CounterOpts is an alias for Opts. See there for doc comments.
 type CounterOpts Opts
 
@@ -143,11 +131,6 @@ func (c *counter) Add(v float64) {
 	}
 }
 
-func (c *counter) AddWithExemplar(v float64, e Labels) {
-	c.Add(v)
-	c.updateExemplar(v, e)
-}
-
 func (c *counter) Inc() {
 	atomic.AddUint64(&c.valInt, 1)
 }
@@ -169,11 +152,11 @@ func (c *counter) Write(out *dto.Metric) error {
 	return populateMetric(CounterValue, val, c.labelPairs, exemplar, out, c.createdTs)
 }
 
-func (c *counter) updateExemplar(v float64, l Labels) {
+func (c *counter) updateExemplar(v float64, l Labels, scheme model.ValidationScheme) {
 	if l == nil {
 		return
 	}
-	e, err := newExemplar(v, c.now(), l)
+	e, err := newExemplar(v, c.now(), l, scheme)
 	if err != nil {
 		panic(err)
 	}

prometheus/counter_globalvalidationscheme.go

@@ -0,0 +1,37 @@
+// Copyright 2025 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !localvalidationscheme
+
+package prometheus
+
+import "github.com/prometheus/common/model"
+
+// ExemplarAdder is implemented by Counters that offer the option of adding a
+// value to the Counter together with an exemplar. Its AddWithExemplar method
+// works like the Add method of the Counter interface but also replaces the
+// currently saved exemplar (if any) with a new one, created from the provided
+// value, the current time as timestamp, and the provided labels. Empty Labels
+// will lead to a valid (label-less) exemplar. But if Labels is nil, the current
+// exemplar is left in place. AddWithExemplar panics if the value is < 0, if any
+// of the provided labels are invalid, or if the provided labels contain more
+// than 128 runes in total.
+type ExemplarAdder interface {
+	AddWithExemplar(value float64, exemplar Labels)
+}
+
+func (c *counter) AddWithExemplar(v float64, e Labels) {
+	c.Add(v)
+	//nolint:staticcheck // model.NameValidationScheme is being phased out.
+	c.updateExemplar(v, e, model.NameValidationScheme)
+}

prometheus/counter_globalvalidationscheme_test.go

@@ -0,0 +1,22 @@
+// Copyright 2025 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !localvalidationscheme
+
+package prometheus
+
+import "github.com/prometheus/common/model"
+
+func addToCounterWithExemplar(counter *counter, v float64, e Labels, _ model.ValidationScheme) {
+	counter.AddWithExemplar(v, e)
+}

prometheus/counter_localvalidationscheme.go

@@ -0,0 +1,36 @@
+// Copyright 2025 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build localvalidationscheme
+
+package prometheus
+
+import "github.com/prometheus/common/model"
+
+// ExemplarAdder is implemented by Counters that offer the option of adding a
+// value to the Counter together with an exemplar. Its AddWithExemplar method
+// works like the Add method of the Counter interface but also replaces the
+// currently saved exemplar (if any) with a new one, created from the provided
+// value, the current time as timestamp, and the provided labels. Empty Labels
+// will lead to a valid (label-less) exemplar. But if Labels is nil, the current
+// exemplar is left in place. AddWithExemplar panics if the value is < 0, if any
+// of the provided labels are invalid, or if the provided labels contain more
+// than 128 runes in total.
+type ExemplarAdder interface {
+	AddWithExemplar(value float64, exemplar Labels, scheme model.ValidationScheme)
+}
+
+func (c *counter) AddWithExemplar(v float64, e Labels, scheme model.ValidationScheme) {
+	c.Add(v)
+	c.updateExemplar(v, e, scheme)
+}