bazelbuild/bazel · error · OptionsParsingException

SetValue operation from invocation policy sets multiple valu

Error message

SetValue operation from invocation policy sets multiple values for %s which does not allow multiple values

What it means

Thrown by applySetValueOperation when a policy's set_value supplies more than one flag_value but the target option does not allow multiple values (not a repeatable/multiple-use flag). Single-valued options cannot accept a list, so the policy is rejected before enforcement.

Source

Thrown at src/main/java/com/google/devtools/common/options/InvocationPolicyEnforcer.java:565

      Level loglevel,
      Object conversionContext,
      ImmutableList.Builder<OptionAndRawValue> invocationPolicyFlagListBuilder)
      throws OptionsParsingException {
    SetValue setValue = flagPolicy.policy.getSetValue();
    OptionDefinition optionDefinition = flagPolicy.description.getOptionDefinition();

    // SetValue.flag_value must have at least 1 value.
    if (setValue.getFlagValueCount() == 0) {
      throw new OptionsParsingException(
          String.format(
              "SetValue operation from invocation policy for %s does not have a value",
              optionDefinition));
    }

    // Flag must allow multiple values if multiple values are specified by the policy.
    if (setValue.getFlagValueCount() > 1
        && !flagPolicy.description.getOptionDefinition().allowsMultiple()) {
      throw new OptionsParsingException(
          String.format(
              "SetValue operation from invocation policy sets multiple values for %s which "
                  + "does not allow multiple values",
              optionDefinition));
    }

    switch (setValue.getBehavior()) {
      case UNDEFINED:
        throw throwUndefinedBehaviorException(flagPolicy.policy);
      case ALLOW_OVERRIDES:
        if (valueDescription != null) {
          // The user set the value for the flag but the flag policy is overridable, so keep the
          // user's value.
          logger.at(loglevel).log(
              "Keeping value '%s' from source '%s' for %s because the invocation policy specifying "
                  + "the value(s) '%s' is overridable",
              valueDescription.getValue(),
              valueDescription.getSourceString(),

View on GitHub (pinned to e6e199d060)

Solutions

Reduce flagValue to exactly one entry for single-valued flags.
If multiple values are genuinely needed, target a repeatable flag (one whose help shows it may be used multiple times).
Check the option definition: bazel help lists whether a flag is repeatable (shows 'multiple uses' semantics).

Example fix

// before
{"flagName":"compilation_mode","setValue":{"flagValue":["opt","dbg"],"behavior":"ALLOW_OVERRIDES"}}

// after
{"flagName":"compilation_mode","setValue":{"flagValue":["opt"],"behavior":"ALLOW_OVERRIDES"}}

Defensive patterns

Strategy: validation

Validate before calling

// Multiple values only for repeatable flags
for (FlagPolicy fp : policy.getFlagPoliciesList()) {
  if (fp.hasSetValue() && fp.getSetValue().getFlagValueCount() > 1) {
    OptionDefinition def = optionIndex.get(fp.getFlagName());
    if (def != null && !def.allowsMultiple()) {
      throw new IllegalStateException(fp.getFlagName() + " is single-valued; supply one flag_value");
    }
  }
}

Try / catch

Catch OptionsParsingException; the message names the single-valued option — trim flagValue to one entry.

Prevention

Check flag repeatability in bazel help before writing multi-value policies
Only list flags (used multiple times) may take multiple flag_value entries
Keep a curated list of which org flags are repeatable

When it happens

Trigger: Policy like {"flagName":"compilation_mode","setValue":{"flagValue":["opt","dbg"],...}} — compilation_mode takes exactly one value. Repeatable flags (allowsMultiple(), e.g. --define-style list flags) are the only ones that may receive multiple values.

Common situations: Policy authors giving multiple 'fallback' values to a single-value flag, copy-pasting a repeatable-flag policy pattern onto a scalar flag, misunderstanding that flagValue is a list only for repeated flags.

Related errors

AI-assisted analysis of bazelbuild/bazel@e6e199d060 (2026-08-14). Data as JSON: /api/errors/d3cba939e0563bac. Report an issue: GitHub.