From 3b30ae77e48a0d290ee37741955919b0dd9ea034 Mon Sep 17 00:00:00 2001
From: David Wells <drwells@email.unc.edu>
Date: Wed, 27 Jul 2022 11:11:24 -0400
Subject: [PATCH] Require PETSc 3.7.0 or newer.

This is six years old at this point.
---
 cmake/configure/configure_30_petsc.cmake         | 13 ++++++-------
 doc/external-libs/petsc.html                     |  2 +-
 doc/news/changes/incompatibilities/20220727Wells |  4 ++++
 3 files changed, 11 insertions(+), 8 deletions(-)
 create mode 100644 doc/news/changes/incompatibilities/20220727Wells

diff --git a/cmake/configure/configure_30_petsc.cmake b/cmake/configure/configure_30_petsc.cmake
index 901557528e..08b8b0f79d 100644
--- a/cmake/configure/configure_30_petsc.cmake
+++ b/cmake/configure/configure_30_petsc.cmake
@@ -30,16 +30,15 @@ MACRO(FEATURE_PETSC_FIND_EXTERNAL var)
     SET(${var} TRUE)
 
     #
-    # We support petsc from version 3.3.x onwards
+    # We support petsc from version 3.7.x onwards
     #
-    IF(PETSC_VERSION_MAJOR LESS 3 OR
-        ((PETSC_VERSION_MAJOR EQUAL 3) AND (PETSC_VERSION_MINOR LESS 3)))
+    IF(${PETSC_VERSION} VERSION_LESS 3.7.0)
       MESSAGE(STATUS "Could not find a sufficiently modern PETSc installation: "
-        "Version >=3.3.0 required!"
+        "Version >=3.7.0 required!"
         )
       SET(PETSC_ADDITIONAL_ERROR_STRING
         "Could not find a sufficiently modern PETSc installation: "
-        "Version >=3.3.0 required!\n"
+        "Version >=3.7.0 required!\n"
         )
       SET(${var} FALSE)
     ENDIF()
@@ -121,7 +120,7 @@ ENDMACRO()
 MACRO(FEATURE_PETSC_CONFIGURE_EXTERNAL)
   SET(DEAL_II_EXPAND_PETSC_MPI_VECTOR "PETScWrappers::MPI::Vector")
   SET(DEAL_II_EXPAND_PETSC_MPI_BLOCKVECTOR "PETScWrappers::MPI::BlockVector")
-  SET(DEAL_II_EXPAND_PETSC_SPARSE_MATRICES 
+  SET(DEAL_II_EXPAND_PETSC_SPARSE_MATRICES
       "PETScWrappers::SparseMatrix"
       "PETScWrappers::MPI::SparseMatrix"
       "PETScWrappers::MPI::BlockSparseMatrix")
@@ -141,7 +140,7 @@ MACRO(FEATURE_PETSC_ERROR_MESSAGE)
   MESSAGE(FATAL_ERROR "\n"
     "Could not find the petsc library!\n"
     ${PETSC_ADDITIONAL_ERROR_STRING}
-    "\nPlease ensure that the petsc library version 3.3.0 or newer is "
+    "\nPlease ensure that the petsc library version 3.7.0 or newer is "
     "installed on your computer and is configured with the same mpi options "
     "as deal.II\n"
     "If the library is not at a default location, either provide some hints\n"
diff --git a/doc/external-libs/petsc.html b/doc/external-libs/petsc.html
index 429e94dd80..0d8fc96acd 100644
--- a/doc/external-libs/petsc.html
+++ b/doc/external-libs/petsc.html
@@ -40,7 +40,7 @@
       <acronym>deal.II</acronym> is version 3.17.1. If you use a later
       version than this and encounter problems, let us
       know. <acronym>deal.II</acronym> does not support versions of PETSc prior
-      to 3.3.0.
+      to 3.7.0.
     </p>
 
     <p>
diff --git a/doc/news/changes/incompatibilities/20220727Wells b/doc/news/changes/incompatibilities/20220727Wells
new file mode 100644
index 0000000000..b94817febe
--- /dev/null
+++ b/doc/news/changes/incompatibilities/20220727Wells
@@ -0,0 +1,4 @@
+Changed: The oldest supported version of PETSc has been increased from 3.3.0
+to 3.7.0.
+<br>
+(David Wells, 2022/07/27)
-- 
2.39.5