From 484cf9c0e8e8946c467e8a2babed9dfd57b5d64c Mon Sep 17 00:00:00 2001
From: Tyler Veness <calcmogul@gmail.com>
Date: Tue, 25 May 2021 10:05:41 -0700
Subject: [PATCH] [wpimath] Suppress the -Wmaybe-uninitialized warning in Eigen
 (#3378)

GCC 11 emits a false positive when compiling Eigen and breaks the
build.

Fixes #3363.
---
 wpimath/.styleguide                               |  4 ++++
 wpimath/eigen-maybe-uninitialized.patch           | 15 +++++++++++++++
 .../Eigen/src/Core/util/DisableStupidWarnings.h   |  4 ++++
 wpimath/update_eigen.py                           |  4 ++++
 4 files changed, 27 insertions(+)
 create mode 100644 wpimath/eigen-maybe-uninitialized.patch

diff --git a/wpimath/.styleguide b/wpimath/.styleguide
index 8c19bcaeb9..b9044c93ed 100644
--- a/wpimath/.styleguide
+++ b/wpimath/.styleguide
@@ -8,6 +8,10 @@ cppSrcFileInclude {
   \.cpp$
 }
 
+modifiableFileExclude {
+  \.patch$
+}
+
 generatedFileExclude {
   src/main/native/cpp/drake/
   src/main/native/eigeninclude/
diff --git a/wpimath/eigen-maybe-uninitialized.patch b/wpimath/eigen-maybe-uninitialized.patch
new file mode 100644
index 0000000000..27144de70b
--- /dev/null
+++ b/wpimath/eigen-maybe-uninitialized.patch
@@ -0,0 +1,15 @@
+diff --git a/wpimath/src/main/native/eigeninclude/Eigen/src/Core/util/DisableStupidWarnings.h b/wpimath/src/main/native/eigeninclude/Eigen/src/Core/util/DisableStupidWarnings.h
+index 74f74cc42..5fe86fa0d 100644
+--- a/wpimath/src/main/native/eigeninclude/Eigen/src/Core/util/DisableStupidWarnings.h
++++ b/wpimath/src/main/native/eigeninclude/Eigen/src/Core/util/DisableStupidWarnings.h
+@@ -61,6 +61,10 @@
+     // See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89325
+     #pragma GCC diagnostic ignored "-Wattributes"
+   #endif
++  #if __GNUC__==11
++    // This warning is a false positive
++    #pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
++  #endif
+ #endif
+ 
+ #if defined __NVCC__
diff --git a/wpimath/src/main/native/eigeninclude/Eigen/src/Core/util/DisableStupidWarnings.h b/wpimath/src/main/native/eigeninclude/Eigen/src/Core/util/DisableStupidWarnings.h
index 74f74cc42b..5fe86fa0d6 100644
--- a/wpimath/src/main/native/eigeninclude/Eigen/src/Core/util/DisableStupidWarnings.h
+++ b/wpimath/src/main/native/eigeninclude/Eigen/src/Core/util/DisableStupidWarnings.h
@@ -61,6 +61,10 @@
     // See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89325
     #pragma GCC diagnostic ignored "-Wattributes"
   #endif
+  #if __GNUC__==11
+    // This warning is a false positive
+    #pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+  #endif
 #endif
 
 #if defined __NVCC__
diff --git a/wpimath/update_eigen.py b/wpimath/update_eigen.py
index e971febff7..ebf7eae854 100755
--- a/wpimath/update_eigen.py
+++ b/wpimath/update_eigen.py
@@ -187,6 +187,10 @@ def main():
             os.makedirs(dest_dir)
         shutil.copyfile(f, dest_file)
 
+    # Apply patches
+    os.chdir(cwd)
+    subprocess.check_output(["git", "apply", "eigen-maybe-uninitialized.patch"])
+
     # Comment out missing headers
     for f in files:
         dest_file = os.path.join(include_root, f)