Bug 1719735 - Have IcuLocale take a null-terminated Span; r=platform-i18n-reviewers,dminor

This simplifies the call sites that take Span locale, and ensures null
termination.

Differential Revision: https://phabricator.services.mozilla.com/D131534

intl/components/src/DateIntervalFormat.cpp

@@ -54,10 +54,10 @@ Result<UniquePtr<DateIntervalFormat>, ICUError> DateIntervalFormat::TryCreate(
     Span<const char> aLocale, Span<const char16_t> aSkeleton,
     Span<const char16_t> aTimeZone) {
   UErrorCode status = U_ZERO_ERROR;
-  UDateIntervalFormat* dif = udtitvfmt_open(
-      IcuLocale(AssertNullTerminatedString(aLocale)), aSkeleton.data(),
-      AssertedCast<int32_t>(aSkeleton.size()), aTimeZone.data(),
-      AssertedCast<int32_t>(aTimeZone.size()), &status);
+  UDateIntervalFormat* dif =
+      udtitvfmt_open(IcuLocale(aLocale), aSkeleton.data(),
+                     AssertedCast<int32_t>(aSkeleton.size()), aTimeZone.data(),
+                     AssertedCast<int32_t>(aTimeZone.size()), &status);
   if (U_FAILURE(status)) {
     return Err(ToICUError(status));
   }

intl/components/src/DateTimeFormat.cpp

@@ -270,10 +270,9 @@ Result<UniquePtr<DateTimeFormat>, ICUError> DateTimeFormat::TryCreateFromStyle(
   }
 
   UErrorCode status = U_ZERO_ERROR;
-  UDateFormat* dateFormat = udat_open(
-      timeStyle, dateStyle, IcuLocale(AssertNullTerminatedString(aLocale)),
-      tzID, tzIDLength,
-      /* pattern */ nullptr, /* pattern length */ -1, &status);
+  UDateFormat* dateFormat =
+      udat_open(timeStyle, dateStyle, IcuLocale(aLocale), tzID, tzIDLength,
+                /* pattern */ nullptr, /* pattern length */ -1, &status);
   if (U_FAILURE(status)) {
     return Err(ToICUError(status));
   }
@@ -554,8 +553,7 @@ DateTimeFormat::TryCreateFromPattern(
 
   // Create the date formatter.
   UDateFormat* dateFormat = udat_open(
-      UDAT_PATTERN, UDAT_PATTERN,
-      IcuLocale(AssertNullTerminatedString(aLocale)), tzID, tzIDLength,
+      UDAT_PATTERN, UDAT_PATTERN, IcuLocale(aLocale), tzID, tzIDLength,
       aPattern.data(), static_cast<int32_t>(aPattern.size()), &status);
 
   if (U_FAILURE(status)) {

intl/components/src/ICU4CGlue.h

@@ -32,15 +32,6 @@
 struct UFormattedValue;
 namespace mozilla::intl {
 
-static inline const char* IcuLocale(const char* aLocale) {
-  // Return the empty string if the input is exactly equal to the string "und".
-  const char* locale = aLocale;
-  if (!std::strcmp(locale, "und")) {
-    locale = "";  // ICU root locale
-  }
-  return locale;
-}
-
 static inline const char* AssertNullTerminatedString(Span<const char> aSpan) {
   // Intentionally check one past the last character, because we expect that the
   // NUL character isn't part of the string.
@@ -63,6 +54,26 @@ static inline const char* AssertNullTerminatedString(std::string_view aView) {
   return aView.data();
 }
 
+/**
+ * Map the "und" locale to an empty string, which the ICU uses internally.
+ */
+static inline const char* IcuLocale(const char* aLocale) {
+  // Return the empty string if the input is exactly equal to the string "und".
+  const char* locale = aLocale;
+  if (!std::strcmp(locale, "und")) {
+    locale = "";  // ICU root locale
+  }
+  return locale;
+}
+
+/**
+ * Ensure a locale is null-terminated, and map the "und" locale to an empty
+ * string, which the ICU uses internally.
+ */
+static inline const char* IcuLocale(Span<const char> aLocale) {
+  return IcuLocale(AssertNullTerminatedString(aLocale));
+}
+
 using ICUResult = Result<Ok, ICUError>;
 
 /**

intl/components/src/ListFormat.cpp

@@ -13,8 +13,8 @@ namespace mozilla::intl {
   UListFormatterWidth uwidth = ToUListFormatterWidth(aOptions.mStyle);
 
   UErrorCode status = U_ZERO_ERROR;
-  UListFormatter* fmt = ulistfmt_openForType(
-      IcuLocale(AssertNullTerminatedString(aLocale)), utype, uwidth, &status);
+  UListFormatter* fmt =
+      ulistfmt_openForType(IcuLocale(aLocale), utype, uwidth, &status);
   if (U_FAILURE(status)) {
     return Err(ICUError::InternalError);
   }