Implement allow_alias for enums

experimental/ir/builtins.go

@@ -48,6 +48,7 @@ type builtins struct {
 	OptionTargets        Member
 	CType, JSType        Member
 	Lazy, UnverifiedLazy Member
+	AllowAlias           Member
 	MessageSet           Member
 
 	JSONName Member

experimental/ir/ir_member.go

@@ -60,10 +60,10 @@ type rawMember struct {
 	options       arena.Pointer[rawValue]
 	oneof         int32
 	optionTargets uint32
+	jsonName      intern.ID
 
-	jsonName intern.ID
-
-	isGroup bool
+	isGroup  bool
+	numberOk bool // An error occurred while computing the field number.
 }
 
 // IsMessageField returns whether this is a non-extension message field.
@@ -584,12 +584,14 @@ type ReservedRange struct {
 }
 
 type rawReservedRange struct {
-	decl          ast.DeclRange
-	value         ast.ExprAny
-	first, last   int32
-	options       arena.Pointer[rawValue]
-	features      arena.Pointer[rawFeatureSet]
+	decl        ast.DeclRange
+	value       ast.ExprAny
+	first, last int32
+	options     arena.Pointer[rawValue]
+	features    arena.Pointer[rawFeatureSet]
+
 	forExtensions bool
+	rangeOk       bool
 }
 
 // AST returns the expression that this range was evaluated from, if known.

experimental/ir/lower_numbers.go

@@ -46,10 +46,8 @@ func evaluateFieldNumbers(f File, r *report.Report) {
 		}
 
 		for member := range seq.Values(ty.Members()) {
-			n, ok := evaluateMemberNumber(f.Context(), scope, member.AST().Value(), kind, false, r)
-			if ok {
-				member.raw.number = n
-			}
+			member.raw.number, member.raw.numberOk = evaluateMemberNumber(
+				f.Context(), scope, member.AST().Value(), kind, false, r)
 		}
 
 		for _, raw := range ty.raw.ranges {
@@ -91,6 +89,7 @@ func evaluateFieldNumbers(f File, r *report.Report) {
 
 				tags.raw.first = start
 				tags.raw.last = end
+				tags.raw.rangeOk = startOk && endOk
 
 			default:
 				n, ok := evaluateMemberNumber(f.Context(), scope, tags.AST(), kind, false, r)
@@ -100,6 +99,7 @@ func evaluateFieldNumbers(f File, r *report.Report) {
 
 				tags.raw.first = n
 				tags.raw.last = n
+				tags.raw.rangeOk = ok
 			}
 		}
 	}
@@ -118,7 +118,8 @@ func evaluateFieldNumbers(f File, r *report.Report) {
 			scope = ty.FullName()
 		}
 
-		extn.raw.number, _ = evaluateMemberNumber(f.Context(), scope, extn.AST().Value(), kind, false, r)
+		extn.raw.number, extn.raw.numberOk = evaluateMemberNumber(
+			f.Context(), scope, extn.AST().Value(), kind, false, r)
 	}
 }
 
@@ -177,7 +178,7 @@ func buildFieldNumberRanges(f File, r *report.Report) {
 			seq.Values(ty.ExtensionRanges()),
 		) {
 			lo, hi := tagRange.Range()
-			if lo == 0 || hi == 0 {
+			if !tagRange.raw.rangeOk {
 				continue // Diagnosed already.
 			}
 			disjoint := ty.raw.rangesByNumber.Insert(lo, hi, rawTagRange{
@@ -198,7 +199,7 @@ func buildFieldNumberRanges(f File, r *report.Report) {
 		// first value is a member.
 		for member := range seq.Values(ty.Members()) {
 			n := member.Number()
-			if n == 0 {
+			if !member.raw.numberOk {
 				continue // Diagnosed already.
 			}
 			ty.raw.rangesByNumber.Insert(n, n, rawTagRange{
@@ -215,6 +216,11 @@ func buildFieldNumberRanges(f File, r *report.Report) {
 			}
 
 			first := TagRange{ty.withContext, entry.Value[0]}
+			if ty.AllowsAlias() && first.raw.isMember {
+				// If all of the members of the intersections are members,
+				// we don't diagnose.
+				continue
+			}
 
 			for _, tags := range entry.Value[1:] {
 				tags := TagRange{ty.withContext, tags}

experimental/ir/lower_validate.go

@@ -26,6 +26,7 @@ import (
 	"github.com/bufbuild/protocompile/experimental/seq"
 	"github.com/bufbuild/protocompile/experimental/token/keyword"
 	"github.com/bufbuild/protocompile/internal/ext/iterx"
+	"github.com/bufbuild/protocompile/internal/ext/mapsx"
 )
 
 // diagnoseUnusedImports generates diagnostics for each unused import.
@@ -98,6 +99,29 @@ func validateEnum(ty Type, r *report.Report) {
 		return
 	}
 
+	// Check if allow_alias is actually used. This does not happen in
+	// lower_numbers.go because we want to be able to include the allow_alias
+	// option span in the diagnostic.
+	if ty.AllowsAlias() {
+		// Check to see if there are at least two enum values with the same
+		// number.
+		var hasAlias bool
+		numbers := make(map[int32]struct{})
+		for member := range seq.Values(ty.Members()) {
+			if !mapsx.AddZero(numbers, member.Number()) {
+				hasAlias = true
+				break
+			}
+		}
+
+		if !hasAlias {
+			option := ty.Options().Field(builtins.AllowAlias)
+			r.Errorf("`%s` requires at least one aliasing %s", option.Field().Name(), taxa.EnumValue).Apply(
+				report.Snippet(option.OptionSpan()),
+			)
+		}
+	}
+
 	first := ty.Members().At(0)
 	if first.Number() != 0 && !ty.IsClosedEnum() {
 		// Figure out why this enum is open.

experimental/ir/testdata/editions/incomplete_feature.proto.symtab.yaml

@@ -16,7 +16,7 @@ tables:
     - { extn: "buf.test.f", name: "d", value: "false" }
     - { extn: "buf.test.f", name: "e", value: "<invalid type>" }
     - { extn: "buf.test.f", name: "f", value: "true" }
-    - { extn: "buf.test.f", name: "g", value: "0" }
+    - { extn: "buf.test.f", name: "g", value: "A" }
     symbols:
     - fqn: "buf.test"
       kind: KIND_PACKAGE
@@ -35,7 +35,7 @@ tables:
       - { extn: "buf.test.f", name: "d", value: "false" }
       - { extn: "buf.test.f", name: "e", value: "<invalid type>" }
       - { extn: "buf.test.f", name: "f", value: "true" }
-      - { extn: "buf.test.f", name: "g", value: "0" }
+      - { extn: "buf.test.f", name: "g", value: "A" }
     - fqn: "buf.test.Enum"
       kind: KIND_ENUM
       file: "testdata/editions/incomplete_feature.proto"
@@ -51,7 +51,7 @@ tables:
       - { extn: "buf.test.f", name: "d", value: "false" }
       - { extn: "buf.test.f", name: "e", value: "<invalid type>" }
       - { extn: "buf.test.f", name: "f", value: "true" }
-      - { extn: "buf.test.f", name: "g", value: "0" }
+      - { extn: "buf.test.f", name: "g", value: "A" }
     - fqn: "buf.test.Features.a"
       kind: KIND_FIELD
       file: "testdata/editions/incomplete_feature.proto"
@@ -70,7 +70,7 @@ tables:
       - { extn: "buf.test.f", name: "d", value: "false" }
       - { extn: "buf.test.f", name: "e", value: "<invalid type>" }
       - { extn: "buf.test.f", name: "f", value: "true" }
-      - { extn: "buf.test.f", name: "g", value: "0" }
+      - { extn: "buf.test.f", name: "g", value: "A" }
     - fqn: "buf.test.Features.b"
       kind: KIND_FIELD
       file: "testdata/editions/incomplete_feature.proto"
@@ -94,7 +94,7 @@ tables:
       - { extn: "buf.test.f", name: "d", value: "false" }
       - { extn: "buf.test.f", name: "e", value: "<invalid type>" }
       - { extn: "buf.test.f", name: "f", value: "true" }
-      - { extn: "buf.test.f", name: "g", value: "0" }
+      - { extn: "buf.test.f", name: "g", value: "A" }
     - fqn: "buf.test.Features.c"
       kind: KIND_FIELD
       file: "testdata/editions/incomplete_feature.proto"
@@ -119,7 +119,7 @@ tables:
       - { extn: "buf.test.f", name: "d", value: "false" }
       - { extn: "buf.test.f", name: "e", value: "<invalid type>" }
       - { extn: "buf.test.f", name: "f", value: "true" }
-      - { extn: "buf.test.f", name: "g", value: "0" }
+      - { extn: "buf.test.f", name: "g", value: "A" }
     - fqn: "buf.test.Features.d"
       kind: KIND_FIELD
       file: "testdata/editions/incomplete_feature.proto"
@@ -145,7 +145,7 @@ tables:
       - { extn: "buf.test.f", name: "d", value: "false" }
       - { extn: "buf.test.f", name: "e", value: "<invalid type>" }
       - { extn: "buf.test.f", name: "f", value: "true" }
-      - { extn: "buf.test.f", name: "g", value: "0" }
+      - { extn: "buf.test.f", name: "g", value: "A" }
     - fqn: "buf.test.Features.e"
       kind: KIND_FIELD
       file: "testdata/editions/incomplete_feature.proto"
@@ -169,7 +169,7 @@ tables:
       - { extn: "buf.test.f", name: "d", value: "false" }
       - { extn: "buf.test.f", name: "e", value: "<invalid type>" }
       - { extn: "buf.test.f", name: "f", value: "true" }
-      - { extn: "buf.test.f", name: "g", value: "0" }
+      - { extn: "buf.test.f", name: "g", value: "A" }
     - fqn: "buf.test.Features.f"
       kind: KIND_FIELD
       file: "testdata/editions/incomplete_feature.proto"
@@ -201,7 +201,7 @@ tables:
       - { extn: "buf.test.f", name: "d", value: "false" }
       - { extn: "buf.test.f", name: "e", value: "<invalid type>" }
       - { extn: "buf.test.f", name: "f", value: "true" }
-      - { extn: "buf.test.f", name: "g", value: "0" }
+      - { extn: "buf.test.f", name: "g", value: "A" }
     - fqn: "buf.test.Features.g"
       kind: KIND_FIELD
       file: "testdata/editions/incomplete_feature.proto"
@@ -227,7 +227,7 @@ tables:
       - { extn: "buf.test.f", name: "d", value: "false" }
       - { extn: "buf.test.f", name: "e", value: "<invalid type>" }
       - { extn: "buf.test.f", name: "f", value: "true" }
-      - { extn: "buf.test.f", name: "g", value: "0" }
+      - { extn: "buf.test.f", name: "g", value: "A" }
     - fqn: "buf.test.A"
       kind: KIND_ENUM_VALUE
       file: "testdata/editions/incomplete_feature.proto"
@@ -241,7 +241,7 @@ tables:
       - { extn: "buf.test.f", name: "d", value: "false" }
       - { extn: "buf.test.f", name: "e", value: "<invalid type>" }
       - { extn: "buf.test.f", name: "f", value: "true" }
-      - { extn: "buf.test.f", name: "g", value: "0" }
+      - { extn: "buf.test.f", name: "g", value: "A" }
     - fqn: "buf.test.B"
       kind: KIND_ENUM_VALUE
       file: "testdata/editions/incomplete_feature.proto"
@@ -255,7 +255,7 @@ tables:
       - { extn: "buf.test.f", name: "d", value: "false" }
       - { extn: "buf.test.f", name: "e", value: "<invalid type>" }
       - { extn: "buf.test.f", name: "f", value: "true" }
-      - { extn: "buf.test.f", name: "g", value: "0" }
+      - { extn: "buf.test.f", name: "g", value: "A" }
     - fqn: "buf.test.f"
       kind: KIND_EXTENSION
       file: "testdata/editions/incomplete_feature.proto"
@@ -273,6 +273,6 @@ tables:
       - { extn: "buf.test.f", name: "d", value: "false" }
       - { extn: "buf.test.f", name: "e", value: "<invalid type>" }
       - { extn: "buf.test.f", name: "f", value: "true" }
-      - { extn: "buf.test.f", name: "g", value: "0" }
+      - { extn: "buf.test.f", name: "g", value: "A" }
     options.message.fields:
       "features": { message.extns: { "buf.test.f": { message: {} } } }

experimental/ir/testdata/tags/allow_alias.proto

@@ -0,0 +1,33 @@
+// Copyright 2020-2025 Buf Technologies, Inc.
+//
+// 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.
+
+edition = "2023";
+
+package buf.test;
+
+enum NoAlias {
+    A1 = 0;
+    B1 = 0;
+}
+
+enum AllowAlias {
+    option allow_alias = true;
+    A2 = 0;
+    B2 = 0;
+}
+
+enum NeedsAlias {
+    option allow_alias = true;
+    A3 = 0;
+}

experimental/ir/testdata/tags/allow_alias.proto.stderr.txt

@@ -0,0 +1,15 @@
+error: enum value `0` used more than once
+  --> testdata/tags/allow_alias.proto:21:10
+   |
+20 |     A1 = 0;
+   |          - previously used here
+21 |     B1 = 0;
+   |          ^ used here
+
+error: `allow_alias` requires at least one aliasing enum value
+  --> testdata/tags/allow_alias.proto:31:12
+   |
+31 |     option allow_alias = true;
+   |            ^^^^^^^^^^^^^^^^^^
+
+encountered 2 errors

experimental/ir/testdata/tags/fields.proto.stderr.txt

@@ -96,6 +96,15 @@ error: field number out of range
    = note: the range for field numbers is `0x1 to 0x1fffffff`,
            minus `0x4a38 to 0x4e1f`, which is reserved for internal use
 
+warning: message fields have the same JSON name
+  --> testdata/tags/fields.proto:33:20
+   |
+31 |     optional int32 z6 = 0xffffffffffffffffffffffffffffffff;
+   |                    -- this implies JSON name `z6`
+32 |
+33 |     optional int32 z6 = -1;
+   |                    ^^ this also implies that name
+
 error: field number out of range
   --> testdata/tags/fields.proto:33:25
    |
@@ -302,4 +311,4 @@ error: cannot find `a` in this scope
    |
    = help: the full name of this scope is `test.M`
 
-encountered 34 errors
+encountered 34 errors and 1 warning

experimental/ir/testdata/tags/reserved.proto

@@ -44,4 +44,9 @@ enum E {
 
     reserved = 100;
     reserved "reserved", "unused";
+}
+
+enum Z {
+    K = 0;
+    reserved 0;
 }

experimental/ir/testdata/tags/reserved.proto.stderr.txt

@@ -166,4 +166,12 @@ error: use of reserved enum value `100`
 45 |     reserved = 100;
    |                ^^^ used here
 
-encountered 16 errors and 2 warnings
+error: use of reserved enum value `0`
+  --> testdata/tags/reserved.proto:50:9
+   |
+50 |     K = 0;
+   |         ^ used here
+51 |     reserved 0;
+   |              - enum value reserved here
+
+encountered 17 errors and 2 warnings