Save all temp files in EMCC_DEBUG mode (emscripten-core#13406)

We have two classes of temp files that we use in emscripten

1. Temp files that live in emscripten temp dir and have non-unique
   names
2. Temp files that live direclyt in the temp dir (not in a subdirectory
   and must have unique names.

The cleanup mechanism we use for these two is separate.
- We keep (1) around when EMCC_DEBUG is set.
- We keep (2) around when EMCC_DEBUG_SAVE is set.

When EMCC_DEBUG is set we also use the emscripten temp dir (1) to store
the files of type (2), but we were still deleting them.

This change makes the saving of temp file consisten such that EMCC_DEBUG
acts as superset of EMCC_DEBUG_SAVE.

This has the nice property that repsonce files and other temporaries are
preserver in debug mode which makes subprocess commands more each to
reproduce.

Author: sbc100

tools/shared.py

@@ -33,6 +33,7 @@
 
 
 DEBUG = int(os.environ.get('EMCC_DEBUG', '0'))
+DEBUG_SAVE = DEBUG or int(os.environ.get('EMCC_DEBUG_SAVE', '0'))
 EXPECTED_NODE_VERSION = (4, 1, 1)
 EXPECTED_BINARYEN_VERSION = 99
 EXPECTED_LLVM_VERSION = "13.0"
@@ -376,12 +377,14 @@ def get_emscripten_temp_dir():
   if not EMSCRIPTEN_TEMP_DIR:
     EMSCRIPTEN_TEMP_DIR = tempfile.mkdtemp(prefix='emscripten_temp_', dir=configuration.TEMP_DIR)
 
-    def prepare_to_clean_temp(d):
-      def clean_temp():
-        try_delete(d)
+    if not DEBUG_SAVE:
+      def prepare_to_clean_temp(d):
+        def clean_temp():
+          try_delete(d)
 
-      atexit.register(clean_temp)
-    prepare_to_clean_temp(EMSCRIPTEN_TEMP_DIR) # this global var might change later
+        atexit.register(clean_temp)
+      # this global var might change later
+      prepare_to_clean_temp(EMSCRIPTEN_TEMP_DIR)
   return EMSCRIPTEN_TEMP_DIR
 
 
@@ -422,9 +425,13 @@ def __init__(self):
         atexit.register(lock.release)
 
   def get_temp_files(self):
-    return tempfiles.TempFiles(
-      tmpdir=self.TEMP_DIR if not DEBUG else get_emscripten_temp_dir(),
-      save_debug_files=os.environ.get('EMCC_DEBUG_SAVE'))
+    if DEBUG_SAVE:
+      # In debug mode store all temp files in the emscripten-specific temp dir
+      # and don't worry about cleaning them up.
+      return tempfiles.TempFiles(get_emscripten_temp_dir(), save_debug_files=True)
+    else:
+      # Otherwise use the system tempdir and try to clean up after ourselves.
+      return tempfiles.TempFiles(self.TEMP_DIR, save_debug_files=False)
 
 
 def apply_configuration():

tools/tempfiles.py

@@ -95,7 +95,7 @@ def get_dir(self):
 
   def clean(self):
     if self.save_debug_files:
-      print(f'not cleaning up temp files since in debug-save mode, see them in ${self.tmpdir}', file=sys.stderr)
+      print(f'not cleaning up temp files since in debug-save mode, see them in {self.tmpdir}', file=sys.stderr)
       return
     for filename in self.to_clean:
       try_delete(filename)