; * etc/PROBLEMS: Mention MinGW problems with -D_FORTIFY_SOURCE=2.

diff --git a/etc/PROBLEMS b/etc/PROBLEMS
index cdce8bbc774f09f2daacb9e932799619a4190c06..30769e68f11a742de6f197cc3d0a1ddd63902a7a 100644 (file)
--- a/etc/PROBLEMS
+++ b/etc/PROBLEMS
@@ -2768,6 +2768,21 @@ With any of the above methods, you'd need to restart Emacs (and
 preferably also your Windows system) after making the changes, to have
 them take effect.
 
+*** MinGW64 Emacs built with -D_FORTIFY_SOURCE=2 misbehaves
+
+Using this preprocessor option when building Emacs with MinGW64
+produces an Emacs binary that behaves incorrectly.  In particular,
+running asynchronous shell command, e.g., with 'M-&', causes Emacs to
+use 100% of CPU and start allocating a lot of memory.  For the same
+reason, asynchronous native-compilation will hang Emacs (which could
+wedge Emacs during startup, if your Emacs is configured to download
+and install packages via package.el every startup).  'M-x run-python',
+'M-x shell', and similar commands also hang.  Other commands might
+also cause high CPU and/or memory usage.
+
+The workaround is to rebuild Emacs without the -D_FORTIFY_SOURCE=2
+option.
+
 ** Emacs on Windows 9X requires UNICOWS.DLL
 
 If that DLL is not available, Emacs will display an error dialog