copybara-service · Oct 14, 2026
diff --git a/bundle/src/main/java/dev/cel/bundle/BUILD.bazel b/bundle/src/main/java/dev/cel/bundle/BUILD.bazel
@@ -110,6 +110,7 @@ java_library(
         "//checker:standard_decl",
         "//common:cel_function_decl",
         "//common:cel_overload_decl",
+        "//common:cel_signature_utils",
         "//common:cel_var_decl",
         "//common:container",
         "//common:options",

diff --git a/bundle/src/main/java/dev/cel/bundle/TypeSpecifierParser.java b/bundle/src/main/java/dev/cel/bundle/TypeSpecifierParser.java
@@ -15,6 +15,10 @@
 package dev.cel.bundle;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static dev.cel.common.CelSignatureUtils.MAX_RECURSION_DEPTH;
+import static dev.cel.common.CelSignatureUtils.isAlpha;
+import static dev.cel.common.CelSignatureUtils.isAlphaNumeric;
+import static dev.cel.common.CelSignatureUtils.isWhitespace;
 
 import com.google.common.collect.ImmutableList;
 import dev.cel.bundle.CelEnvironment.TypeDecl;
@@ -25,7 +29,6 @@
  * {@code "int"}) into a {@link TypeDecl}.
  */
 final class TypeSpecifierParser {
-  private static final int MAX_RECURSION_DEPTH = 64;
   static final TypeDecl ERROR_TYPE_DECL = TypeDecl.create("*error*");
 
   private final String text;
@@ -178,22 +181,14 @@ private String parseTypeParamIdent() {
   private void skipWhitespace() {
     while (pos < length) {
       char c = text.charAt(pos);
-      if (c == ' ' || c == '\t' || c == '\n' || c == '\r') {
+      if (isWhitespace(c)) {
         pos++;
       } else {
         break;
       }
     }
   }
 
-  private static boolean isAlpha(char c) {
-    return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
-  }
-
-  private static boolean isAlphaNumeric(char c) {
-    return isAlpha(c) || (c >= '0' && c <= '9');
-  }
-
   private static String formatQuoted(String s) {
     return "\"" + s + "\"";
   }

diff --git a/checker/src/test/java/dev/cel/checker/CelOverloadDeclTest.java b/checker/src/test/java/dev/cel/checker/CelOverloadDeclTest.java
@@ -21,9 +21,11 @@
 
 import dev.cel.expr.Decl.FunctionDecl.Overload;
 import com.google.common.collect.ImmutableList;
+import dev.cel.common.CelFunctionDecl;
 import dev.cel.common.CelOverloadDecl;
 import dev.cel.common.CelProtoDeclConverter;
 import dev.cel.common.types.CelProtoTypes;
+import dev.cel.common.types.ListType;
 import dev.cel.common.types.SimpleType;
 import dev.cel.common.types.TypeParamType;
 import org.junit.Test;
@@ -105,4 +107,26 @@ public void setParameterTypes_doesNotDedupe() {
         .containsExactly(SimpleType.STRING, SimpleType.STRING, SimpleType.STRING, SimpleType.INT)
         .inOrder();
   }
+
+  @Test
+  public void newFunctionDeclaration_populatesEmptyOverloadIds() {
+    CelOverloadDecl globalOverload =
+        newGlobalOverload(SimpleType.INT, SimpleType.INT, SimpleType.INT);
+    CelOverloadDecl memberOverload =
+        newMemberOverload(
+            SimpleType.BOOL, ListType.create(TypeParamType.create("T")), TypeParamType.create("T"));
+    CelOverloadDecl explicitOverload =
+        newGlobalOverload("custom_id", SimpleType.STRING, SimpleType.STRING);
+
+    assertThat(globalOverload.overloadId()).isEmpty();
+    assertThat(memberOverload.overloadId()).isEmpty();
+
+    CelFunctionDecl functionDecl =
+        CelFunctionDecl.newFunctionDeclaration(
+            "myFunc", globalOverload, memberOverload, explicitOverload);
+
+    assertThat(functionDecl.overloads().stream().map(CelOverloadDecl::overloadId))
+        .containsExactly("myFunc(int,int)", "list<~T>.myFunc(~T)", "custom_id")
+        .inOrder();
+  }
 }
diff --git a/common/BUILD.bazel b/common/BUILD.bazel
@@ -40,6 +40,18 @@ cel_android_library(
     exports = ["//common/src/main/java/dev/cel/common:cel_overload_decl_android"],
 )
 
+java_library(
+    name = "cel_signature_utils",
+    visibility = ["//:internal"],
+    exports = ["//common/src/main/java/dev/cel/common:cel_signature_utils"],
+)
+
+cel_android_library(
+    name = "cel_signature_utils_android",
+    visibility = ["//:internal"],
+    exports = ["//common/src/main/java/dev/cel/common:cel_signature_utils_android"],
+)
+
 java_library(
     name = "cel_proto_decl_converter",
     exports = ["//common/src/main/java/dev/cel/common:cel_proto_decl_converter"],

diff --git a/common/src/main/java/dev/cel/common/BUILD.bazel b/common/src/main/java/dev/cel/common/BUILD.bazel
@@ -63,6 +63,7 @@ java_library(
     ],
     deps = [
         ":cel_overload_decl",
+        ":cel_signature_utils",
         "//:auto_value",
         "@maven//:com_google_errorprone_error_prone_annotations",
         "@maven//:com_google_guava_guava",
@@ -76,12 +77,45 @@ cel_android_library(
     ],
     deps = [
         ":cel_overload_decl_android",
+        ":cel_signature_utils_android",
         "//:auto_value",
         "@maven//:com_google_errorprone_error_prone_annotations",
         "@maven_android//:com_google_guava_guava",
     ],
 )
 
+java_library(
+    name = "cel_signature_utils",
+    srcs = ["CelSignatureUtils.java"],
+    tags = [
+    ],
+    deps = [
+        "//:auto_value",
+        "//common/annotations",
+        "//common/types",
+        "//common/types:cel_types",
+        "//common/types:type_providers",
+        "@maven//:com_google_errorprone_error_prone_annotations",
+        "@maven//:com_google_guava_guava",
+    ],
+)
+
+cel_android_library(
+    name = "cel_signature_utils_android",
+    srcs = ["CelSignatureUtils.java"],
+    tags = [
+    ],
+    deps = [
+        "//:auto_value",
+        "//common/annotations",
+        "//common/types:cel_types_android",
+        "//common/types:type_providers_android",
+        "//common/types:types_android",
+        "@maven//:com_google_errorprone_error_prone_annotations",
+        "@maven_android//:com_google_guava_guava",
+    ],
+)
+
 java_library(
     name = "cel_overload_decl",
     srcs = ["CelOverloadDecl.java"],

diff --git a/common/src/main/java/dev/cel/common/CelFunctionDecl.java b/common/src/main/java/dev/cel/common/CelFunctionDecl.java
@@ -70,9 +70,36 @@ public Builder addOverloads(Iterable<CelOverloadDecl> overloads) {
       return this;
     }
 
+    @CheckReturnValue
+    abstract CelFunctionDecl autoBuild();
+
     /** Builds a new instance of {@link CelFunctionDecl} */
     @CheckReturnValue
-    public abstract CelFunctionDecl build();
+    public CelFunctionDecl build() {
+      CelFunctionDecl functionDecl = autoBuild();
+      boolean needsOverloadId = false;
+      for (CelOverloadDecl overload : functionDecl.overloads()) {
+        if (overload.overloadId().isEmpty()) {
+          needsOverloadId = true;
+          break;
+        }
+      }
+      if (!needsOverloadId) {
+        return functionDecl;
+      }
+      ImmutableSet.Builder<CelOverloadDecl> updatedOverloads = ImmutableSet.builder();
+      for (CelOverloadDecl overload : functionDecl.overloads()) {
+        if (overload.overloadId().isEmpty()) {
+          String generatedId =
+              CelSignatureUtils.makeOverloadSignature(
+                  functionDecl.name(), overload.parameterTypes(), overload.isInstanceFunction());
+          updatedOverloads.add(overload.toBuilder().setOverloadId(generatedId).build());
+        } else {
+          updatedOverloads.add(overload);
+        }
+      }
+      return functionDecl.toBuilder().setOverloads(updatedOverloads.build()).autoBuild();
+    }
   }
 
   public abstract Builder toBuilder();

diff --git a/common/src/main/java/dev/cel/common/CelOverloadDecl.java b/common/src/main/java/dev/cel/common/CelOverloadDecl.java
@@ -41,7 +41,10 @@
 @AutoValue
 @Immutable
 public abstract class CelOverloadDecl {
-  /** Required. Globally unique overload name. */
+  /**
+   * Globally unique overload name. If empty when building {@link CelFunctionDecl}, an overload ID
+   * is automatically generated from the function name and parameter types.
+   */
   public abstract String overloadId();
 
   /**
@@ -79,7 +82,7 @@ public abstract class CelOverloadDecl {
 
   /** Create a new builder to construct a {@link CelOverloadDecl} instance */
   public static Builder newBuilder() {
-    return new AutoValue_CelOverloadDecl.Builder().setDoc("");
+    return new AutoValue_CelOverloadDecl.Builder().setOverloadId("").setDoc("");
   }
 
   /** Builder for configuring the {@link CelOverloadDecl}. */
@@ -153,6 +156,24 @@ public CelOverloadDecl build() {
     }
   }
 
+  /**
+   * Helper method for declaring a member function overload with an automatically generated overload
+   * ID.
+   */
+  @CheckReturnValue
+  public static CelOverloadDecl newMemberOverload(CelType resultType, CelType... paramTypes) {
+    return newMemberOverload("", resultType, Arrays.asList(paramTypes));
+  }
+
+  /**
+   * Helper method for declaring a member function overload with an automatically generated overload
+   * ID.
+   */
+  @CheckReturnValue
+  public static CelOverloadDecl newMemberOverload(CelType resultType, List<CelType> paramTypes) {
+    return newMemberOverload("", /* doc= */ "", resultType, paramTypes);
+  }
+
   /** Helper method for declaring a member function overload */
   @CheckReturnValue
   public static CelOverloadDecl newMemberOverload(
@@ -181,6 +202,24 @@ public static CelOverloadDecl newMemberOverload(
     return newOverload(overloadId, doc, resultType, paramTypes, /* isInstanceFunction= */ true);
   }
 
+  /**
+   * Helper method for declaring a global function overload with an automatically generated overload
+   * ID.
+   */
+  @CheckReturnValue
+  public static CelOverloadDecl newGlobalOverload(CelType resultType, CelType... paramTypes) {
+    return newGlobalOverload("", resultType, Arrays.asList(paramTypes));
+  }
+
+  /**
+   * Helper method for declaring a global function overload with an automatically generated overload
+   * ID.
+   */
+  @CheckReturnValue
+  public static CelOverloadDecl newGlobalOverload(CelType resultType, List<CelType> paramTypes) {
+    return newGlobalOverload("", /* doc= */ "", resultType, paramTypes);
+  }
+
   /** Helper method for declaring a global function overload */
   @CheckReturnValue
   public static CelOverloadDecl newGlobalOverload(