cmake: disable unity mode with Windows Unicode + TrackMemory

"TrackMemory" is `ENABLE_DEBUG=ON` (aka `ENABLE_CURLDEBUG=ON`,
aka `-DCURLDEBUG`).

There is an issue with memory tracking and Unicode when built in "unity"
mode, which results in the curl tool crashing right on startup, even
without any command-line option. Interestingly this doesn't happen under
WINE (at least on the system I tested this on), but consistenly happens
on real Windows machines. Crash is 0xC0000374 heap corruption. Both
shared and static curl executables are affected.

This limitation probably won't hit too many people, but it remains
a TODO to find and fix the root cause and drop this workaround.

Example builds and runs:
https://ci.appveyor.com/project/curlorg/curl/builds/48169111/job/17cptxhtpubd7iwj#L313 (static)
https://ci.appveyor.com/project/curlorg/curl/builds/48169111/job/76e1ge758tbyqu9c#L317 (shared)

Follow-up to 3f8fc25720900b14b7432f4bd93407ca15311719 #11095

Ref: #11928
Closes #12005

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f1de3843a0247b5248ca68388ad196d59b0fe6a5..e6d0e5190e84f670e7fe411b3d58456251f3c3db 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -144,6 +144,16 @@ if(ENABLE_CURLDEBUG)
   set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS CURLDEBUG)
 endif()
 
+# This combination results in curl tool crashing on startup when run on native
+# Windows (it was seen to work when run under WINE though). We disable UNITY
+# mode as a workaround.
+if(ENABLE_UNICODE AND ENABLE_CURLDEBUG)
+  set(CMAKE_UNITY_BUILD OFF)
+  message(WARNING "Unity builds are not supported with Windows Unicode and "
+    "TrackMemory (-DCURLDEBUG) enabled at the same time. Unity mode has been "
+    "disabled.")
+endif()
+
 # For debug libs and exes, add "-d" postfix
 if(NOT DEFINED CMAKE_DEBUG_POSTFIX)
   set(CMAKE_DEBUG_POSTFIX "-d")