demangle stacks in abort(), using new stackTrace utility

src/library.js

@@ -4296,7 +4296,7 @@ LibraryManager.library = {
   },
 
   llvm_trap: function() {
-    throw 'trap! ' + new Error().stack;
+    abort('trap!');
   },
 
   __assert_fail: function(condition, filename, line, func) {

src/postamble.js

@@ -180,7 +180,7 @@ function abort(text) {
   ABORT = true;
   EXITSTATUS = 1;
 
-  throw 'abort() at ' + (new Error().stack);
+  throw 'abort() at ' + stackTrace();
 }
 Module['abort'] = Module.abort = abort;
 

src/preamble.js

@@ -644,7 +644,7 @@ function demangle(func) {
   try {
     if (typeof func === 'number') func = Pointer_stringify(func);
     if (func[0] !== '_') return func;
-    if (func[1] !== '_') return func.substr(1); // C function
+    if (func[1] !== '_') return func; // C function
     if (func[2] !== 'Z') return func;
     var i = 3;
     // params, etc.
@@ -747,10 +747,18 @@ function demangle(func) {
     }
     return parse();
   } catch(e) {
-    return func + '<demangle-err>' + e;
+    return func;
   }
 }
 
+function demangleAll(text) {
+  return text.replace(/__Z[\w\d_]+/, function(x) { var y = demangle(x); return x === y ? x : (x + ' (' + y + ')') });
+}
+
+function stackTrace() {
+  return demangleAll(new Error().stack);
+}
+
 // Memory management
 
 var PAGE_SIZE = 4096;

tests/test_core.py

@@ -9476,6 +9476,32 @@ def process(filename):
       Settings.ALIASING_FUNCTION_POINTERS = 1 - Settings.ALIASING_FUNCTION_POINTERS # flip the test
       self.do_run(src, '''Hello 7 from JS!''')
 
+  def test_demangle_stacks(self):
+    if Settings.ASM_JS: return self.skip('spidermonkey has stack trace issues')
+
+    src = r'''
+      #include<stdio.h>
+      #include<stdlib.h>
+
+      namespace NameSpace {
+        class Class {
+        public:
+          int Aborter(double x, char y, int *z) {
+            int addr = x+y+(int)z;
+            void *p = (void*)addr;
+            for (int i = 0; i < 100; i++) free(p); // will abort, should show proper stack trace
+          }
+        };
+      }
+
+      int main(int argc, char **argv) {
+        NameSpace::Class c;
+        c.Aborter(1.234, 'a', NULL);
+        return 0;
+      }
+    '''
+    self.do_run(src, 'NameSpace::Class::Aborter(double, char, int*)');
+
   def test_embind(self):
     if self.emcc_args is None: return self.skip('requires emcc')
     Building.COMPILER_TEST_OPTS += ['--bind']