Editorial: Prefer returning static values after alias comparison

[gibson042]

I observed in passing that the overwhelming majority of If _alias_ is *value*, … return … steps that return either _alias_ or *value* after determining that the two are equivalent opt for the latter (i.e., return *value*). It seems like a reasonable convention to be cognizant of even if not caught by linting, and this PR cleans up an outlier.

$ gawk '
  BEGIN {
    # `d` is the count of active "1. If …," scopes) and length of `state`.
    d = 0;
  }
  # Handle scope exit, printing blocks that correspond with returning
  # either the alias or the value it was compared against.
  {
    while (d > 0 &&
      (index($0, state[d, "indent"]) != 1 || $1 != "1." || index($0, state[d, "indent"] "1.") == 1)) {

      i = state[d, "start"];
      j = state[d, "end"];
      if (i <= j) print "--";
      while (i <= j) printf "%d: %s\n", i, buf[i++];
      d--;
    }
  }
  # Enter new "If _alias_ is *value*, …" scopes as appropriate.
  match($0, /([[:space:]]*)1[.] If (_[^_]*_) is ([*][^*]*[*]),/, m) {
    d++;
    state[d, "start"] = NR;
    state[d, "end"] = 0;
    state[d, "indent"] = m[1];
    state[d, "alias"] = m[2];
    state[d, "value"] = m[3];
  }
  {
    # Proceed only if inside at least one active scope.
    if (!d) next;

    # Buffer the line.
    buf[NR] = $0;

    # Update the end position of every scope for which we find
    # a corresponding "return _alias_" or "return *value*"
    # (and keep a count of which we find).
    while (match($0, /[Rr]eturn (_[^_]*_|[*][^*]*[*])[.]/, m)) {
      for (j = d; j >= 1; j--) {
        if (m[1] == state[j, "alias"]) {
          state[j, "end"] = NR;
          return_alias++;
        } else if (m[1] == state[j, "value"]) {
          state[j, "end"] = NR;
          return_value++;
        }
      }
      $0 = substr($0, RSTART + RLENGTH);
    }
  }
  END {
    printf "====\nReturn _alias_: %d\nReturn *value*: %d\n", return_alias, return_value;
  }
' spec.html
--
1852:             1. If _x_ is *NaN*, return *NaN*.
--
1883:             1. If _exponent_ is *NaN*, return *NaN*.
--
1885:             1. If _base_ is *NaN*, return *NaN*.
--
4390:           1. If _Desc_ is *undefined*, return *undefined*.
--
5926:             1. If _ny_ is *undefined*, return *undefined*.
--
5930:             1. If _nx_ is *undefined*, return *undefined*.
--
6327:         1. If _status_ is *false*, return *false*.
--
8271:         1. If _hasDuplicates_ is *true*, return *true*.
--
8277:         1. If _hasDuplicate_ is *true*, return *true*.
--
8342:         1. If _hasDuplicates_ is *true*, return *true*.
--
8369:         1. If _hasDuplicates_ is *true*, return *true*.
--
8375:         1. If _hasDuplicates_ is *true*, return *true*.
--
8399:         1. If _hasDuplicates_ is *true*, return *true*.
--
8442:         1. If _hasUndefinedLabels_ is *true*, return *true*.
--
8448:         1. If _hasUndefinedLabels_ is *true*, return *true*.
--
8522:         1. If _hasUndefinedLabels_ is *true*, return *true*.
--
8548:         1. If _hasUndefinedLabels_ is *true*, return *true*.
--
8554:         1. If _hasUndefinedLabels_ is *true*, return *true*.
--
8578:         1. If _hasUndefinedLabels_ is *true*, return *true*.
--
8631:         1. If _hasUndefinedLabels_ is *true*, return *true*.
--
8637:         1. If _hasUndefinedLabels_ is *true*, return *true*.
--
8711:         1. If _hasUndefinedLabels_ is *true*, return *true*.
--
8737:         1. If _hasUndefinedLabels_ is *true*, return *true*.
--
8743:         1. If _hasUndefinedLabels_ is *true*, return *true*.
--
8767:         1. If _hasUndefinedLabels_ is *true*, return *true*.
--
9120:             1. If _contained_ is *true*, return *true*.
--
9282:         1. If _inList_ is *true*, return *true*.
--
10254:             1. If _foundBinding_ is *false*, return *false*.
--
10588:             1. If _home_ is *undefined*, return *undefined*.
--
11033:             1. If _hasProperty_ is *true*, return *true*.
--
12470:           1. If _extensible_ is *false*, return *false*.
--
12644:             1. If _extensible_ is *false*, return *false*.
--
12742:           1. If _desc_ is *undefined*, then
12743:             1. Let _parent_ be ? <emu-meta effects="user-code">_O_.[[GetPrototypeOf]]</emu-meta>().
12744:             1. If _parent_ is *null*, return *undefined*.
--
12749:           1. If _getter_ is *undefined*, return *undefined*.
--
13979:             1. If _succeeded_ is *false*, return *false*.
--
14074:           1. If _succeeded_ is *false*, return *false*.
--
14077:             1. If _deleteSucceeded_ is *false*, then
14078:               1. Set _newLenDesc_.[[Value]] to ! ToUint32(_P_) + *1*<sub>𝔽</sub>.
14079:               1. If _newWritable_ is *false*, set _newLenDesc_.[[Writable]] to *false*.
14080:               1. Perform ! OrdinaryDefineOwnProperty(_A_, *"length"*, _newLenDesc_).
14081:               1. Return *false*.
--
14197:           1. If _index_ is *undefined*, return *undefined*.
--
14248:           1. If _desc_ is *undefined*, return _desc_.
--
14277:           1. If _allowed_ is *false*, return *false*.
--
14492:               1. If _value_ is *undefined*, return *undefined*.
--
15196:         1. If _booleanTrapResult_ is *false*, return *false*.
--
15198:         1. If _extensibleTarget_ is *true*, return *true*.
--
15303:           1. If _targetDesc_ is *undefined*, return *undefined*.
--
15302:         1. If _trapResultObj_ is *undefined*, then
15303:           1. If _targetDesc_ is *undefined*, return *undefined*.
15304:           1. If _targetDesc_.[[Configurable]] is *false*, throw a *TypeError* exception.
15305:           1. Let _extensibleTarget_ be ? IsExtensible(_target_).
15306:           1. If _extensibleTarget_ is *false*, throw a *TypeError* exception.
15307:           1. Return *undefined*.
--
15367:         1. If _booleanTrapResult_ is *false*, return *false*.
--
15511:         1. If _booleanTrapResult_ is *false*, return *false*.
--
15555:         1. If _booleanTrapResult_ is *false*, return *false*.
--
19985:         1. If _r_ is *undefined*, return *false*. Otherwise, return _r_.
--
19994:         1. If _r_ is *undefined*, return *false*. Otherwise, return _r_.
--
20101:         1. If _r_ is *true*, return *false*. Otherwise, return *true*.
--
20118:         1. If _r_ is *true*, return *false*. Otherwise, return *true*.
--
22930:         1. If _has_ is *true*, return *true*.
--
22936:         1. If _has_ is *true*, return *true*.
--
22942:         1. If _has_ is *true*, return *true*.
--
22952:         1. If _has_ is *true*, return *true*.
--
25241:         1. If _has_ is *true*, return *true*.
--
25283:         1. If _has_ is *true*, return *true*.
--
25331:         1. If _has_ is *true*, return *true*.
--
25333:         1. If _has_ is *true*, return *true*.
--
25340:         1. If _has_ is *true*, return *true*.
--
25481:         1. If _has_ is *true*, return *true*.
--
31557:           1. If _n_ is *NaN*, return *NaN*.
--
31571:           1. If _n_ is *NaN*, _n_ > *1*<sub>𝔽</sub>, or _n_ &lt; *-1*<sub>𝔽</sub>, return *NaN*.
--
31734:           1. If _n_ is *NaN*, return *NaN*.
--
31790:           1. If _n_ is *NaN*, return *NaN*.
--
31811:             1. If _number_ is *NaN*, return *NaN*.
--
31899:             1. If _number_ is *NaN*, return *NaN*.
--
31921:             1. If _number_ is *NaN*, return *NaN*.
--
32543:           1. If _year_ is *NaN*, return *NaN*.
--
33024:           1. If _t_ is *NaN*, return *NaN*.
--
33034:           1. If _t_ is *NaN*, return *NaN*.
--
33044:           1. If _t_ is *NaN*, return *NaN*.
--
33054:           1. If _t_ is *NaN*, return *NaN*.
--
33064:           1. If _t_ is *NaN*, return *NaN*.
--
33074:           1. If _t_ is *NaN*, return *NaN*.
--
33084:           1. If _t_ is *NaN*, return *NaN*.
--
33094:           1. If _t_ is *NaN*, return *NaN*.
--
33112:           1. If _t_ is *NaN*, return *NaN*.
--
33122:           1. If _t_ is *NaN*, return *NaN*.
--
33132:           1. If _t_ is *NaN*, return *NaN*.
--
33142:           1. If _t_ is *NaN*, return *NaN*.
--
33152:           1. If _t_ is *NaN*, return *NaN*.
--
33162:           1. If _t_ is *NaN*, return *NaN*.
--
33172:           1. If _t_ is *NaN*, return *NaN*.
--
33182:           1. If _t_ is *NaN*, return *NaN*.
--
33192:           1. If _t_ is *NaN*, return *NaN*.
--
33203:           1. If _t_ is *NaN*, return *NaN*.
--
33241:           1. If _t_ is *NaN*, return *NaN*.
--
33263:           1. If _t_ is *NaN*, return *NaN*.
--
33280:           1. If _t_ is *NaN*, return *NaN*.
--
33302:           1. If _t_ is *NaN*, return *NaN*.
--
33323:           1. If _t_ is *NaN*, return *NaN*.
--
33355:           1. If _t_ is *NaN*, return *NaN*.
--
33392:           1. If _t_ is *NaN*, return *NaN*.
--
33413:           1. If _t_ is *NaN*, return *NaN*.
--
33429:           1. If _t_ is *NaN*, return *NaN*.
--
33450:           1. If _t_ is *NaN*, return *NaN*.
--
33470:           1. If _t_ is *NaN*, return *NaN*.
--
37367:               1. If _result_ is *null*, then
37368:                 1. If _n_ = 0, return *null*.
--
38350:               1. If _testResult_ is *false*, return *false*.
--
39056:               1. If _testResult_ is *true*, return *true*.
--
39053:             1. If _kPresent_ is *true*, then
39054:               1. Let _kValue_ be ? Get(_O_, _Pk_).
39055:               1. Let _testResult_ be ToBoolean(? Call(_callbackfn_, _thisArg_, « _kValue_, 𝔽(_k_), _O_ »)).
39056:               1. If _testResult_ is *true*, return *true*.
--
40054:             1. If _testResult_ is *false*, return *false*.
--
40593:             1. If _testResult_ is *true*, return *true*.
--
46082:             1. If _resultCapability_ is *undefined*, then
46083:               1. Return *undefined*.
--
49291:           1. If _t_ is *NaN*, return *NaN*.
====
Return _alias_: 3
Return *value*: 105

[bakkot]

I've made a note to lint this, at least in simple cases.