Avoid double-reporting the filename in JS library errors/warnings

As part of this I also avoid converting JS libraries path to absolute
paths where possible.  This means that errors and warnings show the
actual pathname passed by the users, and not some absolute path.  This
makes writing tests for the double-reporting issue easier, and makes the
errors/warnings easier to read (IMHO).

Author: sbc100

src/parseTools.mjs

@@ -152,7 +152,7 @@ export function preprocess(filename) {
             }
             const absPath = findIncludeFile(includeFile, path.dirname(filename));
             if (!absPath) {
-              error(`${filename}:${i + 1}: file not found: ${includeFile}`);
+              error(`file not found: ${includeFile}`, i + 1);
               continue;
             }
             const result = preprocess(absPath);
@@ -164,7 +164,7 @@ export function preprocess(filename) {
           }
         } else if (first === '#else') {
           if (showStack.length == 0) {
-            error(`${filename}:${i + 1}: #else without matching #if`);
+            error('#else without matching #if', i + 1);
           }
           const curr = showStack.pop();
           if (curr == IGNORE) {
@@ -174,23 +174,21 @@ export function preprocess(filename) {
           }
         } else if (first === '#endif') {
           if (showStack.length == 0) {
-            error(`${filename}:${i + 1}: #endif without matching #if`);
+            error('#endif without matching #if', i + 1);
           }
           showStack.pop();
         } else if (first === '#warning') {
           if (showCurrentLine()) {
-            warn(
-              `${filename}:${i + 1}: #warning ${trimmed.substring(trimmed.indexOf(' ')).trim()}`,
-            );
+            warn(`#warning ${trimmed.substring(trimmed.indexOf(' ')).trim()}`, i + 1);
           }
         } else if (first === '#error') {
           if (showCurrentLine()) {
-            error(`${filename}:${i + 1}: #error ${trimmed.substring(trimmed.indexOf(' ')).trim()}`);
+            error(`#error ${trimmed.substring(trimmed.indexOf(' ')).trim()}`, i + 1);
           }
         } else if (first === '#preprocess') {
           // Do nothing
         } else {
-          error(`${filename}:${i + 1}: Unknown preprocessor directive ${first}`);
+          error(`Unknown preprocessor directive ${first}`, i + 1);
         }
       } else {
         if (showCurrentLine()) {

src/utility.mjs

@@ -56,17 +56,19 @@ export function popCurrentFile() {
   currentFile.pop();
 }
 
-function errorPrefix() {
-  if (currentFile.length > 0) {
-    return currentFile[currentFile.length - 1] + ': ';
+function errorPrefix(lineNo) {
+  if (!currentFile.length) return '';
+  const filename = currentFile[currentFile.length - 1];
+  if (lineNo) {
+    return `${filename}:${lineNo}: `;
   } else {
-    return '';
+    return `${filename}: `;
   }
 }
 
-export function warn(msg) {
+export function warn(msg, lineNo) {
   warnings = true;
-  printErr(`warning: ${errorPrefix()}${msg}`);
+  printErr(`warning: ${errorPrefix(lineNo)}${msg}`);
 }
 
 const seenWarnings = new Set();
@@ -84,9 +86,9 @@ export function errorOccured() {
   return abortExecution;
 }
 
-export function error(msg) {
+export function error(msg, lineNo) {
   abortExecution = true;
-  printErr(`error: ${errorPrefix()}${msg}`);
+  printErr(`error: ${errorPrefix(lineNo)}${msg}`);
 }
 
 function range(size) {

test/test_other.py

@@ -4915,24 +4915,26 @@ def test_jslib_search_path(self):
 
   # Tests using the #warning directive in JS library files
   def test_jslib_warnings(self):
-    proc = self.run_process([EMCC, test_file('hello_world.c'), '--js-library', test_file('warning_in_js_libraries.js')], stdout=PIPE, stderr=PIPE)
+    shutil.copy(test_file('warning_in_js_libraries.js'), '.')
+    proc = self.run_process([EMCC, test_file('hello_world.c'), '--js-library', 'warning_in_js_libraries.js'], stdout=PIPE, stderr=PIPE)
     self.assertNotContained('This warning should not be present!', proc.stderr)
-    self.assertContained('warning_in_js_libraries.js:5: #warning This is a warning string!', proc.stderr)
-    self.assertContained('warning_in_js_libraries.js:7: #warning This is a second warning string!', proc.stderr)
+    self.assertContained('warning: warning_in_js_libraries.js:5: #warning This is a warning string!', proc.stderr)
+    self.assertContained('warning: warning_in_js_libraries.js:7: #warning This is a second warning string!', proc.stderr)
     self.assertContained('emcc: warning: warnings in JS library compilation [-Wjs-compiler]', proc.stderr)
 
-    err = self.expect_fail([EMCC, test_file('hello_world.c'), '--js-library', test_file('warning_in_js_libraries.js'), '-Werror'])
+    err = self.expect_fail([EMCC, test_file('hello_world.c'), '--js-library', 'warning_in_js_libraries.js', '-Werror'])
     self.assertNotContained('This warning should not be present!', err)
-    self.assertContained('warning_in_js_libraries.js:5: #warning This is a warning string!', err)
-    self.assertContained('warning_in_js_libraries.js:7: #warning This is a second warning string!', err)
+    self.assertContained('warning: warning_in_js_libraries.js:5: #warning This is a warning string!', err)
+    self.assertContained('warning: warning_in_js_libraries.js:7: #warning This is a second warning string!', err)
     self.assertContained('emcc: error: warnings in JS library compilation [-Wjs-compiler] [-Werror]', err)
 
   # Tests using the #error directive in JS library files
   def test_jslib_errors(self):
-    err = self.expect_fail([EMCC, test_file('hello_world.c'), '--js-library', test_file('error_in_js_libraries.js')])
+    shutil.copy(test_file('error_in_js_libraries.js'), '.')
+    err = self.expect_fail([EMCC, test_file('hello_world.c'), '--js-library', 'error_in_js_libraries.js'])
     self.assertNotContained('This error should not be present!', err)
-    self.assertContained('error_in_js_libraries.js:5: #error This is an error string!', err)
-    self.assertContained('error_in_js_libraries.js:7: #error This is a second error string!', err)
+    self.assertContained('error: error_in_js_libraries.js:5: #error This is an error string!', err)
+    self.assertContained('error: error_in_js_libraries.js:7: #error This is a second error string!', err)
 
   def test_jslib_include(self):
     create_file('inc.js', '''