Make second argument of UTF8ArrayToString optional. NFC (emscripten-core#22696)

This is mostly a wash from a code size POV but makes the call sites more
readable I think.

Author: sbc100

src/library.js

@@ -1534,7 +1534,7 @@ addToLibrary({
   emscripten_log__deps: ['$formatString', '$emscriptenLog'],
   emscripten_log: (flags, format, varargs) => {
     var result = formatString(format, varargs);
-    var str = UTF8ArrayToString(result, 0);
+    var str = UTF8ArrayToString(result);
     emscriptenLog(flags, str);
   },
 

src/library_fs.js

@@ -1303,7 +1303,7 @@ FS.staticInit();
       var buf = new Uint8Array(length);
       FS.read(stream, buf, 0, length, 0);
       if (opts.encoding === 'utf8') {
-        ret = UTF8ArrayToString(buf, 0);
+        ret = UTF8ArrayToString(buf);
       } else if (opts.encoding === 'binary') {
         ret = buf;
       }

src/library_strings.js

@@ -20,14 +20,14 @@ addToLibrary({
    * array that contains uint8 values, returns a copy of that string as a
    * Javascript String object.
    * heapOrArray is either a regular array, or a JavaScript typed array view.
-   * @param {number} idx
+   * @param {number=} idx
    * @param {number=} maxBytesToRead
    * @return {string}
    */`,
 #if TEXTDECODER
   $UTF8ArrayToString__deps: ['$UTF8Decoder'],
 #endif
-  $UTF8ArrayToString: (heapOrArray, idx, maxBytesToRead) => {
+  $UTF8ArrayToString: (heapOrArray, idx = 0, maxBytesToRead = NaN) => {
 #if CAN_ADDRESS_2GB
     idx >>>= 0;
 #endif
@@ -38,7 +38,7 @@ addToLibrary({
     // null terminator by itself.  Also, use the length info to avoid running tiny
     // strings through TextDecoder, since .subarray() allocates garbage.
     // (As a tiny code save trick, compare endPtr against endIdx using a negation,
-    // so that undefined means Infinity)
+    // so that undefined/NaN means Infinity)
     while (heapOrArray[endPtr] && !(endPtr >= endIdx)) ++endPtr;
 #endif // TEXTDECODER
 

src/library_tty.js

@@ -106,15 +106,15 @@ addToLibrary({
       },
       put_char(tty, val) {
         if (val === null || val === {{{ charCode('\n') }}}) {
-          out(UTF8ArrayToString(tty.output, 0));
+          out(UTF8ArrayToString(tty.output));
           tty.output = [];
         } else {
           if (val != 0) tty.output.push(val); // val == 0 would cut text output off in the middle.
         }
       },
       fsync(tty) {
         if (tty.output && tty.output.length > 0) {
-          out(UTF8ArrayToString(tty.output, 0));
+          out(UTF8ArrayToString(tty.output));
           tty.output = [];
         }
       },
@@ -143,15 +143,15 @@ addToLibrary({
     default_tty1_ops: {
       put_char(tty, val) {
         if (val === null || val === {{{ charCode('\n') }}}) {
-          err(UTF8ArrayToString(tty.output, 0));
+          err(UTF8ArrayToString(tty.output));
           tty.output = [];
         } else {
           if (val != 0) tty.output.push(val);
         }
       },
       fsync(tty) {
         if (tty.output && tty.output.length > 0) {
-          err(UTF8ArrayToString(tty.output, 0));
+          err(UTF8ArrayToString(tty.output));
           tty.output = [];
         }
       }

src/library_wasi.js

@@ -245,7 +245,7 @@ var WasiLibrary = {
     assert(buffer);
 #endif
     if (curr === 0 || curr === {{{ charCode('\n') }}}) {
-      (stream === 1 ? out : err)(UTF8ArrayToString(buffer, 0));
+      (stream === 1 ? out : err)(UTF8ArrayToString(buffer));
       buffer.length = 0;
     } else {
       buffer.push(curr);

src/library_wasmfs.js

@@ -146,7 +146,7 @@ FS.init();
       // The buffer contents exist 8 bytes after the returned pointer.
       var ret = new Uint8Array(HEAPU8.subarray(buf + 8, buf + 8 + length));
       if (opts.encoding === 'utf8') {
-        ret = UTF8ArrayToString(ret, 0);
+        ret = UTF8ArrayToString(ret);
       }
 
       return ret;

src/source_map_support.js

@@ -103,7 +103,7 @@ if (!isDataURI(wasmSourceMapFile)) {
 
 function getSourceMap() {
   var buf = readBinary(wasmSourceMapFile);
-  return JSON.parse(UTF8ArrayToString(buf, 0, buf.length));
+  return JSON.parse(UTF8ArrayToString(buf));
 }
 
 function getSourceMapPromise() {

test/js_optimizer/applyImportAndExportNameChanges2-output.js

@@ -101,7 +101,7 @@ var SYSCALLS = {
   printChar: function(stream, curr) {
     var buffer = SYSCALLS.buffers[stream];
     if (curr === 0 || curr === 10) {
-      (stream === 1 ? out : err)(UTF8ArrayToString(buffer, 0));
+      (stream === 1 ? out : err)(UTF8ArrayToString(buffer));
       buffer.length = 0;
     } else {
       buffer.push(curr);

test/js_optimizer/applyImportAndExportNameChanges2.js

@@ -87,7 +87,7 @@ var SYSCALLS = {
     printChar: (function(stream, curr) {
         var buffer = SYSCALLS.buffers[stream];
         if (curr === 0 || curr === 10) {
-            (stream === 1 ? out : err)(UTF8ArrayToString(buffer, 0));
+            (stream === 1 ? out : err)(UTF8ArrayToString(buffer));
             buffer.length = 0
         } else {
             buffer.push(curr)

test/other/codesize/test_codesize_cxx_wasmfs.gzsize

@@ -1 +1 @@
-3899
+3894

test/other/codesize/test_codesize_cxx_wasmfs.jssize

@@ -1 +1 @@
-8636
+8628

test/other/codesize/test_codesize_files_js_fs.gzsize

@@ -1 +1 @@
-7594
+7595

test/other/codesize/test_codesize_files_js_fs.jssize

@@ -1 +1 @@
-18702
+18696

test/other/codesize/test_codesize_files_wasmfs.gzsize

@@ -1 +1 @@
-2984
+2976

test/other/codesize/test_codesize_files_wasmfs.jssize

@@ -1 +1 @@
-6272
+6265

test/other/codesize/test_codesize_hello_dylink.gzsize

@@ -1 +1 @@
-6319
+6326

test/other/codesize/test_codesize_hello_dylink.jssize

@@ -1 +1 @@
-13868
+13872

test/other/codesize/test_codesize_minimal_pthreads.gzsize

@@ -1 +1 @@
-4948
+4951

test/other/codesize/test_codesize_minimal_pthreads.jssize

@@ -1 +1 @@
-10453
+10465

test/other/test_emit_tsd.d.ts

@@ -5,11 +5,11 @@ declare namespace RuntimeExports {
      * array that contains uint8 values, returns a copy of that string as a
      * Javascript String object.
      * heapOrArray is either a regular array, or a JavaScript typed array view.
-     * @param {number} idx
+     * @param {number=} idx
      * @param {number=} maxBytesToRead
      * @return {string}
      */
-    function UTF8ArrayToString(heapOrArray: any, idx: number, maxBytesToRead?: number | undefined): string;
+    function UTF8ArrayToString(heapOrArray: any, idx?: number | undefined, maxBytesToRead?: number | undefined): string;
     let wasmTable: WebAssembly.Table;
     let HEAPF32: any;
     let HEAPF64: any;

test/other/test_unoptimized_code_size.js.size

@@ -1 +1 @@
-54846
+54854

test/other/test_unoptimized_code_size_no_asserts.js.size

@@ -1 +1 @@
-30510
+30518

test/other/test_unoptimized_code_size_strict.js.size

@@ -1 +1 @@
-53824
+53832

test/test_other.py

@@ -1691,7 +1691,7 @@ def test_module_stdout_stderr(self):
 Module['postRun'] = () => {
     assert(stderr.length === 0, 'stderr should be empty. \\n' +
         'stderr: \\n' + stderr);
-    assert(UTF8ArrayToString(stdout, 0).startsWith('hello, world!'), 'stdout should start with the famous greeting. \\n' +
+    assert(UTF8ArrayToString(stdout).startsWith('hello, world!'), 'stdout should start with the famous greeting. \\n' +
         'stdout: \\n' + stdout);
 }
 ''')

test/wasmfs/wasmfs_readfile.c

@@ -31,7 +31,7 @@ int main() {
 
   EM_ASM({
     var output = FS.readFile("/root/test");
-    out(UTF8ArrayToString(output, 0));
+    out(UTF8ArrayToString(output));
     out("Length: " + output.byteLength);
     var err = FS.unlink("/root/test");
     out("FS.unlink: " + err);