errorCode

errorCode

Error message

icupkg: swapInvChars(output package name) failed - %s

What it means

icupkg appends a U_TREE_ENTRY_SEP_CHAR to the package prefix and swaps those invariant characters to the output charset via swapInvChars. If the swap reports a failure, the tool exits with the propagated error code. This catches prefixes containing characters that are not invariant across the target charset.

Source

Thrown at deps/icu-small/source/tools/toolutil/package.cpp:785

    }

    // prepare and swap the package name with a tree separator
    // for prepending to item names
    if(pkgPrefix[0]==0) {
        prefixLength = static_cast<int32_t>(strlen(prefix));
    } else {
        prefixLength = static_cast<int32_t>(strlen(pkgPrefix));
        memcpy(prefix, pkgPrefix, prefixLength);
        if(prefixEndsWithType) {
            prefix[prefixLength-1]=outType;
        }
    }
    prefix[prefixLength++]=U_TREE_ENTRY_SEP_CHAR;
    prefix[prefixLength]=0;
    if(dsLocalToOut!=nullptr) {
        dsLocalToOut->swapInvChars(dsLocalToOut, prefix, prefixLength, prefix, &errorCode);
        if(U_FAILURE(errorCode)) {
            fprintf(stderr, "icupkg: swapInvChars(output package name) failed - %s\n", u_errorName(errorCode));
            exit(errorCode);
        }

        // swap and sort the item names (sorting needs to be done in the output charset)
        dsLocalToOut->swapInvChars(dsLocalToOut, inStrings, inStringTop, inStrings, &errorCode);
        if(U_FAILURE(errorCode)) {
            fprintf(stderr, "icupkg: swapInvChars(item names) failed - %s\n", u_errorName(errorCode));
            exit(errorCode);
        }
        sortItems();
    }

    // create the output item names in sorted order, with the package name prepended to each
    for(i=0; i<itemCount; ++i) {
        length = static_cast<int32_t>(strlen(items[i].name));
        name=allocString(false, length+prefixLength);
        memcpy(name, prefix, prefixLength);
        memcpy(name+prefixLength, items[i].name, length+1);

View on GitHub (pinned to 1b2de5e052)

Solutions

Ensure the package name/prefix uses only ICU invariant characters (printable ASCII alphanumerics, '.', '_').
Use the canonical package basename derived by extractPackageName rather than a custom prefix.
Switch the output type to one matching the source charset family to avoid the invariant-char swap.

Example fix

# before - prefix with non-invariant chars
icupkg -p "my-pkg_v2" -te out.dat

# after - use ASCII-only canonical prefix
icupkg -p "mypkg" -te out.dat

Defensive patterns

Strategy: validation

Validate before calling

# Validate that the package prefix contains only ICU invariant characters
# (ASCII letters, digits, '.', '_') before swapping.
case "$PKG" in
  *[!A-Za-z0-9._]*) echo "prefix '$PKG' has non-invariant chars" >&2; exit 1 ;;
esac
icupkg -p "$PKG" -te out.dat

Prevention

Use only ASCII alphanumeric characters, '.', and '_' in package names.
Prefer the canonical basename produced by extractPackageName.
Avoid EBCDIC output unless the prefix is ASCII-invariant.

When it happens

Trigger: In writePackage, 'dsLocalToOut->swapInvChars(...prefix...) returns U_FAILURE(errorCode). Triggered when the package prefix contains bytes that are not valid invariant characters for the output charset family (e.g. non-ASCII in a prefix being swapped to EBCDIC).

Common situations: A package name with non-ASCII or unusual punctuation; an output charset family that does not cover the prefix's characters; a hand-set pkgPrefix from a non-canonical source.

Related errors

AI-assisted analysis of nodejs/node@1b2de5e052 (2026-08-13). Data as JSON: /api/errors/b9b4b4c2398bfba2. Report an issue: GitHub.