ICU-22939 MF2: Re-implement resolved values and implement bidi default strategy

Implement the changes to resolved values necessary to implement function
composition.

Implement lazy/call-by-need evaluation (instead of lazy-call-by-name
evaluation).

Implement the default bidi strategy and APIs for controlling it.

Update spec tests to those from the current version of the
message-format-wg repo, except for currency and math tests (these
functions are not yet implemented).

Author: catamorphism

icu4c/source/i18n/messageformat2.cpp

@@ -133,6 +133,18 @@ namespace message2 {
         return result;
     }
 
+    template<typename T>
+    inline T* create(const T& node, UErrorCode& status) {
+        if (U_FAILURE(status)) {
+            return nullptr;
+        }
+        T* result = new T(node);
+        if (result == nullptr) {
+            status = U_MEMORY_ALLOCATION_ERROR;
+        }
+        return result;
+    }
+
 } // namespace message2
 
 U_NAMESPACE_END

icu4c/source/i18n/messageformat2_allocation.h

@@ -33,10 +33,6 @@ namespace message2 {
         addError(DynamicError(DynamicErrorType::BadOptionError, formatterName), status);
     }
 
-    void DynamicErrors::setRecoverableBadOption(const FunctionName& formatterName, UErrorCode& status) {
-        addError(DynamicError(DynamicErrorType::RecoverableBadOptionError, formatterName), status);
-    }
-
     void DynamicErrors::setOperandMismatchError(const FunctionName& formatterName, UErrorCode& status) {
         addError(DynamicError(DynamicErrorType::OperandMismatchError, formatterName), status);
     }
@@ -145,8 +141,7 @@ namespace message2 {
                 status = U_MF_FORMATTING_ERROR;
                 break;
             }
-            case DynamicErrorType::BadOptionError:
-            case DynamicErrorType::RecoverableBadOptionError: {
+            case DynamicErrorType::BadOptionError: {
                 status = U_MF_BAD_OPTION;
                 break;
             }
@@ -246,10 +241,6 @@ namespace message2 {
             resolutionAndFormattingErrors->adoptElement(errorP, status);
             break;
         }
-        case DynamicErrorType::RecoverableBadOptionError: {
-            resolutionAndFormattingErrors->adoptElement(errorP, status);
-            break;
-        }
         }
     }
 

icu4c/source/i18n/messageformat2_errors.cpp

@@ -67,16 +67,6 @@ namespace message2 {
         UnresolvedVariable,
         FormattingError,
         BadOptionError,
-        /**
-           This is used to signal errors from :number and :integer when a
-            bad `select` option is passed. In this case, fallback output
-            is not used, so it must be distinguished from a regular bad
-            option error (but it maps to a bad option error in the final
-            error code).
-            See https://github.com/unicode-org/message-format-wg/blob/main/spec/functions/number.md#number-selection
-            "The formatting of the _resolved value_ is not affected by the `select` option.")
-        */
-        RecoverableBadOptionError,
         OperandMismatchError,
         SelectorError,
         UnknownFunction,
@@ -141,7 +131,6 @@ namespace message2 {
         // Used when the name of the offending formatter is unknown
         void setFormattingError(UErrorCode&);
         void setBadOption(const FunctionName&, UErrorCode&);
-        void setRecoverableBadOption(const FunctionName&, UErrorCode&);
         void setOperandMismatchError(const FunctionName&, UErrorCode&);
         bool hasDataModelError() const { return staticErrors.hasDataModelError(); }
         bool hasFormattingError() const { return formattingError; }