diff --git a/etc/bashrc b/etc/bashrc
index d74b2bb61b..b8a6c01783 100644
--- a/etc/bashrc
+++ b/etc/bashrc
@@ -66,9 +66,8 @@ export WM_PROJECT_VERSION=com
 export WM_COMPILER_TYPE=system
 
 # [WM_COMPILER] - Compiler:
-# = Gcc | Clang | Icc | Icx | Amd | Arm | Cray | Fujitsu |
+# = Gcc | Clang | Icc | Icx | Amd | Arm | Cray | Fujitsu | Nvidia |
 #   Gcc<digits> | Clang<digits>
-#   [Not well tested: Pgi | Nvidia]
 export WM_COMPILER=Gcc
 
 # [WM_PRECISION_OPTION] - Floating-point precision:
diff --git a/etc/cshrc b/etc/cshrc
index 1ae0e25093..6417a1d198 100644
--- a/etc/cshrc
+++ b/etc/cshrc
@@ -66,9 +66,8 @@ setenv WM_PROJECT_VERSION com
 setenv WM_COMPILER_TYPE system
 
 # [WM_COMPILER] - Compiler:
-# = Gcc | Clang | Icc | Icx | Amd | Arm | Cray | Fujitsu |
+# = Gcc | Clang | Icc | Icx | Amd | Arm | Cray | Fujitsu | Nvidia |
 #   Gcc<digits> | Clang<digits>
-#   [Not well tested: Pgi | Nvidia]
 setenv WM_COMPILER Gcc
 
 # [WM_PRECISION_OPTION] - Floating-point precision:
diff --git a/wmake/rules/General/Clang/c b/wmake/rules/General/Clang/c
index 2a9345ffe0..efd501e007 100644
--- a/wmake/rules/General/Clang/c
+++ b/wmake/rules/General/Clang/c
@@ -5,6 +5,6 @@ cc          = clang$(COMPILER_VERSION)
 cARCH       =
 cDBUG       =
 cOPT        = -O2
-cWARN       = -Wall $(FOAM_EXTRA_CFLAGS)
+cWARN       = -Wall
 
 #------------------------------------------------------------------------------
diff --git a/wmake/rules/General/Clang/c++ b/wmake/rules/General/Clang/c++
index fa907322cf..28d18859e7 100644
--- a/wmake/rules/General/Clang/c++
+++ b/wmake/rules/General/Clang/c++
@@ -8,17 +8,14 @@ c++DBUG     =
 c++OPT      = -O2
 ptFLAGS     = -DNoRepository -ftemplate-depth-100
 
-# - Standard warnings
-# - Less restrictive warnings (may be needed for flex++, CGAL, etc.)
-
 c++WARN     = \
     -Wall -Wextra -Wold-style-cast \
     -Wnon-virtual-dtor -Wno-unused-parameter -Wno-invalid-offsetof \
     -Wno-undefined-var-template \
-    -Wno-unknown-warning-option \
-    $(FOAM_EXTRA_CXXFLAGS)
+    -Wno-unknown-warning-option
 
-# Many extra warnings from boost
+# Less restrictive warnings (eg, for flex++, CGAL, etc.)
+# - many extra warnings from boost
 c++LESSWARN = \
     -Wno-old-style-cast -Wno-unused-local-typedefs \
     -Wno-tautological-undefined-compare -Wno-shift-negative-value \
diff --git a/wmake/rules/General/Gcc/c b/wmake/rules/General/Gcc/c
index 98b90c0a28..e8407942b3 100644
--- a/wmake/rules/General/Gcc/c
+++ b/wmake/rules/General/Gcc/c
@@ -5,6 +5,6 @@ cc          = gcc$(COMPILER_VERSION)
 cARCH       =
 cDBUG       =
 cOPT        = -O2
-cWARN       = -Wall $(FOAM_EXTRA_CFLAGS)
+cWARN       = -Wall
 
 #------------------------------------------------------------------------------
diff --git a/wmake/rules/General/Gcc/c++ b/wmake/rules/General/Gcc/c++
index c93a90677a..c88dbfe9be 100644
--- a/wmake/rules/General/Gcc/c++
+++ b/wmake/rules/General/Gcc/c++
@@ -13,15 +13,12 @@ c++DBUG     =
 c++OPT      = -O2
 ptFLAGS     = -DNoRepository -ftemplate-depth-100
 
-# - Standard warnings
-# - Less restrictive warnings (may be needed for flex++, CGAL, etc.)
-
 c++WARN     = \
     -Wall -Wextra -Wold-style-cast \
     -Wnon-virtual-dtor -Wno-unused-parameter -Wno-invalid-offsetof \
-    -Wno-attributes -Wno-unknown-pragmas \
-    $(FOAM_EXTRA_CXXFLAGS)
+    -Wno-attributes -Wno-unknown-pragmas
 
+# Less restrictive warnings (eg, for flex++, CGAL, etc.)
 c++LESSWARN = \
     -Wno-old-style-cast -Wno-unused-local-typedefs -Wno-array-bounds \
     -Wno-deprecated-declarations \
diff --git a/wmake/rules/General/Icc/c b/wmake/rules/General/Icc/c
index b6241cf5fb..46a064ccfe 100644
--- a/wmake/rules/General/Icc/c
+++ b/wmake/rules/General/Icc/c
@@ -5,6 +5,6 @@ cc          = icc$(COMPILER_VERSION)
 cARCH       =
 cDBUG       =
 cOPT        = -O2
-cWARN       = $(FOAM_EXTRA_CFLAGS)
+cWARN       =
 
 #------------------------------------------------------------------------------
diff --git a/wmake/rules/General/Icc/c++ b/wmake/rules/General/Icc/c++
index 59bb7ce819..4e13545245 100644
--- a/wmake/rules/General/Icc/c++
+++ b/wmake/rules/General/Icc/c++
@@ -10,16 +10,13 @@ c++DBUG     =
 c++OPT      = -O2
 ptFLAGS     = -DNoRepository
 
-# - Standard warnings
-# - Less restrictive warnings (may be needed for flex++, CGAL, etc.).
-
 c++WARN     = \
     -Wall -Wextra \
     -Wnon-virtual-dtor -Wno-unused-parameter -Wno-invalid-offsetof \
     -Wno-unknown-pragmas \
-    -diag-disable 327,654,1125,1292,2289,2304,11062,11074,11076 \
-    $(FOAM_EXTRA_CXXFLAGS)
+    -diag-disable 327,654,1125,1292,2289,2304,11062,11074,11076
 
+# Less restrictive warnings (eg, for flex++, CGAL, etc.)
 c++LESSWARN = \
     -diag-disable 1224,2026,2305
 
diff --git a/wmake/rules/General/Icx/c b/wmake/rules/General/Icx/c
index c1092af649..e329f9fe24 100644
--- a/wmake/rules/General/Icx/c
+++ b/wmake/rules/General/Icx/c
@@ -5,6 +5,6 @@ cc          = icx$(COMPILER_VERSION)
 cARCH       =
 cDBUG       =
 cOPT        = -O2
-cWARN       = $(FOAM_EXTRA_CFLAGS)
+cWARN       =
 
 #------------------------------------------------------------------------------
diff --git a/wmake/rules/General/Icx/c++ b/wmake/rules/General/Icx/c++
index dd15512484..b6b831f599 100644
--- a/wmake/rules/General/Icx/c++
+++ b/wmake/rules/General/Icx/c++
@@ -10,17 +10,14 @@ c++DBUG     =
 c++OPT      = -O2
 ptFLAGS     = -DNoRepository
 
-# - Standard warnings
-# - Less restrictive warnings (may be needed for flex++, CGAL, etc.).
-
 c++WARN     = \
     -Wall -Wextra \
     -Wnon-virtual-dtor -Wno-unused-parameter -Wno-invalid-offsetof \
     -Wno-unknown-pragmas \
     -Wno-undefined-var-template \
-    -diag-disable 327,654,1125,1292,2289,2304,11062,11074,11076 \
-    $(FOAM_EXTRA_CXXFLAGS)
+    -diag-disable 327,654,1125,1292,2289,2304,11062,11074,11076
 
+# Less restrictive warnings (eg, for flex++, CGAL, etc.)
 c++LESSWARN = \
     -diag-disable 1224,2026,2305
 
diff --git a/wmake/rules/General/Nvidia/c b/wmake/rules/General/Nvidia/c
index 80622c4938..42648c606d 100644
--- a/wmake/rules/General/Nvidia/c
+++ b/wmake/rules/General/Nvidia/c
@@ -8,6 +8,6 @@ cc          = nvc$(COMPILER_VERSION)
 cARCH       =
 cDBUG       =
 cOPT        = -O2
-cWARN       = $(FOAM_EXTRA_CFLAGS)
+cWARN       =
 
 #------------------------------------------------------------------------------
diff --git a/wmake/rules/General/Nvidia/c++ b/wmake/rules/General/Nvidia/c++
index f4945017d5..22ef41972b 100644
--- a/wmake/rules/General/Nvidia/c++
+++ b/wmake/rules/General/Nvidia/c++
@@ -10,15 +10,12 @@ c++DBUG     =
 c++OPT      = -O2
 ptFLAGS     = -DNoRepository
 
-# - Standard warnings
-# - Less restrictive warnings (may be needed for flex++, CGAL, etc.)
-
 c++WARN     = \
     -Wall -Wextra \
     --diag_suppress=111,128,177,185,612,998,1098 \
-    --display_error_number \
-    $(FOAM_EXTRA_CXXFLAGS)
+    --display_error_number
 
+# Less restrictive warnings (eg, for flex++, CGAL, etc.)
 c++LESSWARN =
 
 # Warnings
diff --git a/wmake/rules/General/Pgi/c b/wmake/rules/General/Pgi/c
deleted file mode 100644
index a798bac592..0000000000
--- a/wmake/rules/General/Pgi/c
+++ /dev/null
@@ -1,10 +0,0 @@
-SUFFIXES += .c
-
-cc          = pgcc$(COMPILER_VERSION)
-
-cARCH       =
-cDBUG       =
-cOPT        = -O2
-cWARN       = $(FOAM_EXTRA_CFLAGS)
-
-#------------------------------------------------------------------------------
diff --git a/wmake/rules/General/Pgi/c++ b/wmake/rules/General/Pgi/c++
deleted file mode 100644
index 8a5b6d8ffc..0000000000
--- a/wmake/rules/General/Pgi/c++
+++ /dev/null
@@ -1,21 +0,0 @@
-#------------------------------------------------------------------------------
-# PGI Compilers are defunct - now in NVIDIA HPC SDK  (2021)
-#------------------------------------------------------------------------------
-SUFFIXES += .C .cc .cpp .cxx
-
-CC          = pgc++$(COMPILER_VERSION) -std=c++11
-
-c++ARCH     =
-c++DBUG     =
-c++OPT      = -O2
-ptFLAGS     = -DNoRepository
-
-# - Standard warnings
-# - Less restrictive warnings (may be needed for flex++, CGAL, etc.)
-
-c++WARN     = \
-    $(FOAM_EXTRA_CXXFLAGS)
-
-c++LESSWARN =
-
-#------------------------------------------------------------------------------
diff --git a/wmake/rules/General/Pgi/link-c b/wmake/rules/General/Pgi/link-c
deleted file mode 100644
index 79d1f2b6be..0000000000
--- a/wmake/rules/General/Pgi/link-c
+++ /dev/null
@@ -1,5 +0,0 @@
-LINK_LIBS   = $(cDBUG)
-
-LINKLIBSO   = $(cc) $(cARCH) -shared
-
-LINKEXE     = $(cc) $(cARCH) -Xlinker --add-needed -Xlinker -z -Xlinker nodefs
diff --git a/wmake/rules/General/Pgi/link-c++ b/wmake/rules/General/Pgi/link-c++
deleted file mode 100644
index 1713460ec3..0000000000
--- a/wmake/rules/General/Pgi/link-c++
+++ /dev/null
@@ -1,8 +0,0 @@
-LINK_LIBS   = $(c++DBUG)
-
-LINKLIBSO   = $(CC) $(c++FLAGS) -shared \
-    $(FOAM_EXTRA_LDFLAGS)
-
-LINKEXE     = $(CC) $(c++FLAGS) \
-    -Xlinker --add-needed \
-    $(FOAM_EXTRA_LDFLAGS)
diff --git a/wmake/rules/General/Pgi/openmp b/wmake/rules/General/Pgi/openmp
deleted file mode 100644
index cd007d1529..0000000000
--- a/wmake/rules/General/Pgi/openmp
+++ /dev/null
@@ -1,5 +0,0 @@
-# Flags for compiling/linking openmp
-# The USE_OMP is for OpenFOAM-specific use (general use is _OPENMP)
-
-COMP_OPENMP = -DUSE_OMP -fopenmp
-LINK_OPENMP = -lgomp
diff --git a/wmake/rules/darwin64Clang/c b/wmake/rules/darwin64Clang/c
index 2183b94a0c..70c7e06576 100644
--- a/wmake/rules/darwin64Clang/c
+++ b/wmake/rules/darwin64Clang/c
@@ -6,7 +6,9 @@ cARCH       = -m64 -ftrapping-math
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/darwin64Clang/c++ b/wmake/rules/darwin64Clang/c++
index 1d0bd1225b..8c2eeba107 100644
--- a/wmake/rules/darwin64Clang/c++
+++ b/wmake/rules/darwin64Clang/c++
@@ -5,7 +5,9 @@ c++ARCH     = -m64 -pthread -ftrapping-math
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linux64Amd/c b/wmake/rules/linux64Amd/c
index 1852358f43..4c9ccb90a4 100644
--- a/wmake/rules/linux64Amd/c
+++ b/wmake/rules/linux64Amd/c
@@ -8,7 +8,9 @@ cARCH       = -m64
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linux64Amd/c++ b/wmake/rules/linux64Amd/c++
index 110baa9ecd..dc505aea43 100644
--- a/wmake/rules/linux64Amd/c++
+++ b/wmake/rules/linux64Amd/c++
@@ -6,7 +6,9 @@ c++ARCH     = -m64 -pthread
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linux64Clang/c b/wmake/rules/linux64Clang/c
index a668305639..bba9283dc2 100644
--- a/wmake/rules/linux64Clang/c
+++ b/wmake/rules/linux64Clang/c
@@ -6,7 +6,9 @@ cARCH       = -m64
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linux64Clang/c++ b/wmake/rules/linux64Clang/c++
index bb4d4f8dcd..13ddf7f566 100644
--- a/wmake/rules/linux64Clang/c++
+++ b/wmake/rules/linux64Clang/c++
@@ -5,7 +5,9 @@ c++ARCH     = -m64 -pthread
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linux64Cray/c b/wmake/rules/linux64Cray/c
index c79987784c..cfe2235d0c 100644
--- a/wmake/rules/linux64Cray/c
+++ b/wmake/rules/linux64Cray/c
@@ -10,7 +10,9 @@ cARCH       = -m64
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linux64Cray/c++ b/wmake/rules/linux64Cray/c++
index 62c2dab161..5d4468d64f 100644
--- a/wmake/rules/linux64Cray/c++
+++ b/wmake/rules/linux64Cray/c++
@@ -10,7 +10,9 @@ c++ARCH     = -m64 -pthread
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linux64Gcc/c b/wmake/rules/linux64Gcc/c
index 1997811fb1..61b4b1e089 100644
--- a/wmake/rules/linux64Gcc/c
+++ b/wmake/rules/linux64Gcc/c
@@ -6,7 +6,9 @@ cARCH       = -m64
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linux64Gcc/c++ b/wmake/rules/linux64Gcc/c++
index 721283ae35..a698ff281f 100644
--- a/wmake/rules/linux64Gcc/c++
+++ b/wmake/rules/linux64Gcc/c++
@@ -5,7 +5,9 @@ c++ARCH     = -m64 -pthread
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linux64Icc/c b/wmake/rules/linux64Icc/c
index c73cd82371..34d6b1dd54 100644
--- a/wmake/rules/linux64Icc/c
+++ b/wmake/rules/linux64Icc/c
@@ -6,7 +6,9 @@ cARCH       =
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linux64Icc/c++ b/wmake/rules/linux64Icc/c++
index dedfa0e36c..52c4f81ec1 100644
--- a/wmake/rules/linux64Icc/c++
+++ b/wmake/rules/linux64Icc/c++
@@ -5,7 +5,9 @@ c++ARCH     = -pthread -fp-trap=common -fp-model precise
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linux64Icx/c b/wmake/rules/linux64Icx/c
index 5ee26506cb..d9d8e19b0e 100644
--- a/wmake/rules/linux64Icx/c
+++ b/wmake/rules/linux64Icx/c
@@ -6,7 +6,9 @@ cARCH       =
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linux64Icx/c++ b/wmake/rules/linux64Icx/c++
index db3f2e4916..ae174b3322 100644
--- a/wmake/rules/linux64Icx/c++
+++ b/wmake/rules/linux64Icx/c++
@@ -5,7 +5,9 @@ c++ARCH     = -fp-model precise
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linux64Mingw/c b/wmake/rules/linux64Mingw/c
index 90325552f5..7490a1bdec 100644
--- a/wmake/rules/linux64Mingw/c
+++ b/wmake/rules/linux64Mingw/c
@@ -8,7 +8,9 @@ cc          = x86_64-w64-mingw32-gcc
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS)
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS)
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linux64Mingw/c++ b/wmake/rules/linux64Mingw/c++
index a10e5ffb36..071e93b5ff 100644
--- a/wmake/rules/linux64Mingw/c++
+++ b/wmake/rules/linux64Mingw/c++
@@ -10,7 +10,9 @@ CC          = x86_64-w64-mingw32-g++ -std=gnu++14
 
 include $(RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS)
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS)
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linux64Nvidia/c b/wmake/rules/linux64Nvidia/c
index f1a1058661..783f888a5e 100644
--- a/wmake/rules/linux64Nvidia/c
+++ b/wmake/rules/linux64Nvidia/c
@@ -6,7 +6,9 @@ cARCH       = -m64
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linux64Nvidia/c++ b/wmake/rules/linux64Nvidia/c++
index a4396ce0ea..e1048e2068 100644
--- a/wmake/rules/linux64Nvidia/c++
+++ b/wmake/rules/linux64Nvidia/c++
@@ -5,7 +5,9 @@ c++ARCH     = -m64
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linux64Nvidia/general b/wmake/rules/linux64Nvidia/general
index 5cfb798fac..5aeb8b64d6 100644
--- a/wmake/rules/linux64Nvidia/general
+++ b/wmake/rules/linux64Nvidia/general
@@ -1,7 +1,7 @@
 CPP        = cpp -traditional-cpp $(GFLAGS)
 
 include $(GENERAL_RULES)/standard
-## include $(GENERAL_RULES)/Pgi/openmp
+## include $(GENERAL_RULES)/Nvidia/openmp
 
 ifneq (,$(findstring ~openmp,$(WM_COMPILE_CONTROL)))
     include $(GENERAL_RULES)/no-openmp
diff --git a/wmake/rules/linux64Pgi/c b/wmake/rules/linux64Pgi/c
deleted file mode 100644
index f22dc71af0..0000000000
--- a/wmake/rules/linux64Pgi/c
+++ /dev/null
@@ -1,15 +0,0 @@
-#------------------------------------------------------------------------------
-include $(GENERAL_RULES)/Pgi/c
-
-cARCH       = -m64
-
-# Compile option is non-mandatory, but must be non-empty
-sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
-
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
-
-ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
-
-include $(GENERAL_RULES)/Pgi/link-c
-
-#------------------------------------------------------------------------------
diff --git a/wmake/rules/linux64Pgi/c++ b/wmake/rules/linux64Pgi/c++
deleted file mode 100644
index d5d76ccf3c..0000000000
--- a/wmake/rules/linux64Pgi/c++
+++ /dev/null
@@ -1,17 +0,0 @@
-#------------------------------------------------------------------------------
-include $(GENERAL_RULES)/Pgi/c++
-
-c++ARCH     = -m64
-
-include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
-
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
-
-Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
-cctoo       = $(Ctoo)
-cpptoo      = $(Ctoo)
-cxxtoo      = $(Ctoo)
-
-include $(GENERAL_RULES)/Pgi/link-c++
-
-#------------------------------------------------------------------------------
diff --git a/wmake/rules/linux64Pgi/c++Debug b/wmake/rules/linux64Pgi/c++Debug
deleted file mode 100644
index 48f0b6643e..0000000000
--- a/wmake/rules/linux64Pgi/c++Debug
+++ /dev/null
@@ -1,2 +0,0 @@
-c++DBUG     = -g -DFULLDEBUG
-c++OPT      = -O0
diff --git a/wmake/rules/linux64Pgi/c++Opt b/wmake/rules/linux64Pgi/c++Opt
deleted file mode 100644
index 2aedabd628..0000000000
--- a/wmake/rules/linux64Pgi/c++Opt
+++ /dev/null
@@ -1,2 +0,0 @@
-c++DBUG     =
-c++OPT      = -O3
diff --git a/wmake/rules/linux64Pgi/c++Prof b/wmake/rules/linux64Pgi/c++Prof
deleted file mode 100644
index 3bda4dad55..0000000000
--- a/wmake/rules/linux64Pgi/c++Prof
+++ /dev/null
@@ -1,2 +0,0 @@
-c++DBUG    = -pg
-c++OPT     = -O2
diff --git a/wmake/rules/linux64Pgi/cDebug b/wmake/rules/linux64Pgi/cDebug
deleted file mode 100644
index 7b7adf10de..0000000000
--- a/wmake/rules/linux64Pgi/cDebug
+++ /dev/null
@@ -1,2 +0,0 @@
-cDBUG       = -g -DFULLDEBUG
-cOPT        = -O0
diff --git a/wmake/rules/linux64Pgi/cOpt b/wmake/rules/linux64Pgi/cOpt
deleted file mode 100644
index 17318709f1..0000000000
--- a/wmake/rules/linux64Pgi/cOpt
+++ /dev/null
@@ -1,2 +0,0 @@
-cDBUG       =
-cOPT        = -O3
diff --git a/wmake/rules/linux64Pgi/cProf b/wmake/rules/linux64Pgi/cProf
deleted file mode 100644
index ca3ac9bf5f..0000000000
--- a/wmake/rules/linux64Pgi/cProf
+++ /dev/null
@@ -1,2 +0,0 @@
-cDBUG       = -pg
-cOPT        = -O2
diff --git a/wmake/rules/linux64Pgi/general b/wmake/rules/linux64Pgi/general
deleted file mode 100644
index 5cfb798fac..0000000000
--- a/wmake/rules/linux64Pgi/general
+++ /dev/null
@@ -1,13 +0,0 @@
-CPP        = cpp -traditional-cpp $(GFLAGS)
-
-include $(GENERAL_RULES)/standard
-## include $(GENERAL_RULES)/Pgi/openmp
-
-ifneq (,$(findstring ~openmp,$(WM_COMPILE_CONTROL)))
-    include $(GENERAL_RULES)/no-openmp
-endif
-
-include $(DEFAULT_RULES)/c
-include $(DEFAULT_RULES)/c++
-
-# -----------------------------------------------------------------------------
diff --git a/wmake/rules/linux64Pgi/mplibOPENMPI b/wmake/rules/linux64Pgi/mplibOPENMPI
deleted file mode 100644
index 0faf49ed1e..0000000000
--- a/wmake/rules/linux64Pgi/mplibOPENMPI
+++ /dev/null
@@ -1,3 +0,0 @@
-PFLAGS     = -DMPICH_SKIP_MPICXX -DOMPI_SKIP_MPICXX
-PINC       = -I$(MPI_ARCH_PATH)/include
-PLIBS      = -L$(MPI_ARCH_PATH)/lib$(WM_COMPILER_LIB_ARCH) -L$(MPI_ARCH_PATH)/lib -lmpi
diff --git a/wmake/rules/linuxARM64Arm/c b/wmake/rules/linuxARM64Arm/c
index 8d08c845f6..7cf6cb6f4a 100644
--- a/wmake/rules/linuxARM64Arm/c
+++ b/wmake/rules/linuxARM64Arm/c
@@ -10,7 +10,9 @@ cARCH       = -mcpu=native
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linuxARM64Arm/c++ b/wmake/rules/linuxARM64Arm/c++
index 516dd022c9..f3111f6c04 100644
--- a/wmake/rules/linuxARM64Arm/c++
+++ b/wmake/rules/linuxARM64Arm/c++
@@ -9,7 +9,9 @@ c++ARCH     = -mcpu=native -pthread
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linuxARM64Clang/c b/wmake/rules/linuxARM64Clang/c
index 494e897b4e..ad4b153a6f 100644
--- a/wmake/rules/linuxARM64Clang/c
+++ b/wmake/rules/linuxARM64Clang/c
@@ -6,7 +6,9 @@ cARCH       =
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linuxARM64Clang/c++ b/wmake/rules/linuxARM64Clang/c++
index 2630199a76..b9209aace2 100644
--- a/wmake/rules/linuxARM64Clang/c++
+++ b/wmake/rules/linuxARM64Clang/c++
@@ -5,7 +5,9 @@ c++ARCH     = -pthread
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linuxARM64Fujitsu/c b/wmake/rules/linuxARM64Fujitsu/c
index 29e7168814..c8e74fc1f5 100644
--- a/wmake/rules/linuxARM64Fujitsu/c
+++ b/wmake/rules/linuxARM64Fujitsu/c
@@ -10,7 +10,9 @@ cARCH       =
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linuxARM64Fujitsu/c++ b/wmake/rules/linuxARM64Fujitsu/c++
index c47653608b..e04cdb79b3 100644
--- a/wmake/rules/linuxARM64Fujitsu/c++
+++ b/wmake/rules/linuxARM64Fujitsu/c++
@@ -9,7 +9,9 @@ c++ARCH     = -pthread
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linuxARM64Gcc/c b/wmake/rules/linuxARM64Gcc/c
index 780163c03b..43975404c3 100644
--- a/wmake/rules/linuxARM64Gcc/c
+++ b/wmake/rules/linuxARM64Gcc/c
@@ -6,7 +6,9 @@ cARCH       =
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linuxARM64Gcc/c++ b/wmake/rules/linuxARM64Gcc/c++
index d56488659a..a42cc55e95 100644
--- a/wmake/rules/linuxARM64Gcc/c++
+++ b/wmake/rules/linuxARM64Gcc/c++
@@ -5,7 +5,9 @@ c++ARCH     = -pthread
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linuxARM64Nvidia/c b/wmake/rules/linuxARM64Nvidia/c
index b1447dd9fe..90da0e87fb 100644
--- a/wmake/rules/linuxARM64Nvidia/c
+++ b/wmake/rules/linuxARM64Nvidia/c
@@ -6,7 +6,9 @@ cARCH       =
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linuxARM64Nvidia/c++ b/wmake/rules/linuxARM64Nvidia/c++
index e3e45d1788..d8fa193375 100644
--- a/wmake/rules/linuxARM64Nvidia/c++
+++ b/wmake/rules/linuxARM64Nvidia/c++
@@ -5,7 +5,9 @@ c++ARCH     =
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linuxARM64Nvidia/general b/wmake/rules/linuxARM64Nvidia/general
index 5cfb798fac..5aeb8b64d6 100644
--- a/wmake/rules/linuxARM64Nvidia/general
+++ b/wmake/rules/linuxARM64Nvidia/general
@@ -1,7 +1,7 @@
 CPP        = cpp -traditional-cpp $(GFLAGS)
 
 include $(GENERAL_RULES)/standard
-## include $(GENERAL_RULES)/Pgi/openmp
+## include $(GENERAL_RULES)/Nvidia/openmp
 
 ifneq (,$(findstring ~openmp,$(WM_COMPILE_CONTROL)))
     include $(GENERAL_RULES)/no-openmp
diff --git a/wmake/rules/linuxARM7Gcc/c b/wmake/rules/linuxARM7Gcc/c
index 8e0e0cbc62..d55ba40c01 100644
--- a/wmake/rules/linuxARM7Gcc/c
+++ b/wmake/rules/linuxARM7Gcc/c
@@ -6,7 +6,9 @@ cARCH       = -mcpu=cortex-a9
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linuxARM7Gcc/c++ b/wmake/rules/linuxARM7Gcc/c++
index 353eff851f..0182c5d20a 100644
--- a/wmake/rules/linuxARM7Gcc/c++
+++ b/wmake/rules/linuxARM7Gcc/c++
@@ -5,7 +5,9 @@ c++ARCH     = -mcpu=cortex-a9 -pthread
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linuxClang/c b/wmake/rules/linuxClang/c
index 432b4f2d84..82ed3a452a 100644
--- a/wmake/rules/linuxClang/c
+++ b/wmake/rules/linuxClang/c
@@ -6,7 +6,9 @@ cARCH       = -m32
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linuxClang/c++ b/wmake/rules/linuxClang/c++
index 8e9501272f..2e2d8e06da 100644
--- a/wmake/rules/linuxClang/c++
+++ b/wmake/rules/linuxClang/c++
@@ -5,7 +5,9 @@ c++ARCH     = -m32 -pthread
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linuxGcc/c b/wmake/rules/linuxGcc/c
index c6221f74f1..b8f94d5e2a 100644
--- a/wmake/rules/linuxGcc/c
+++ b/wmake/rules/linuxGcc/c
@@ -6,7 +6,9 @@ cARCH       = -m32
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linuxGcc/c++ b/wmake/rules/linuxGcc/c++
index a946050dbd..2f10dce225 100644
--- a/wmake/rules/linuxGcc/c++
+++ b/wmake/rules/linuxGcc/c++
@@ -5,7 +5,9 @@ c++ARCH     = -m32 -pthread
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linuxIA64Gcc/c b/wmake/rules/linuxIA64Gcc/c
index 780163c03b..43975404c3 100644
--- a/wmake/rules/linuxIA64Gcc/c
+++ b/wmake/rules/linuxIA64Gcc/c
@@ -6,7 +6,9 @@ cARCH       =
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linuxIA64Gcc/c++ b/wmake/rules/linuxIA64Gcc/c++
index 12e48d243f..c6c8eda9e1 100644
--- a/wmake/rules/linuxIA64Gcc/c++
+++ b/wmake/rules/linuxIA64Gcc/c++
@@ -5,7 +5,9 @@ c++ARCH     =
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linuxIA64Icc/c b/wmake/rules/linuxIA64Icc/c
index 5b1f512ec9..de628fdb32 100644
--- a/wmake/rules/linuxIA64Icc/c
+++ b/wmake/rules/linuxIA64Icc/c
@@ -6,7 +6,9 @@ cARCH       =
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linuxIA64Icc/c++ b/wmake/rules/linuxIA64Icc/c++
index e30a2a2958..54a5d2cb1c 100644
--- a/wmake/rules/linuxIA64Icc/c++
+++ b/wmake/rules/linuxIA64Icc/c++
@@ -5,7 +5,9 @@ c++ARCH     =
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linuxIcc/c b/wmake/rules/linuxIcc/c
index f6a1996246..28084de505 100644
--- a/wmake/rules/linuxIcc/c
+++ b/wmake/rules/linuxIcc/c
@@ -6,7 +6,9 @@ cARCH       = -gcc-version=400
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linuxIcc/c++ b/wmake/rules/linuxIcc/c++
index a0d5ff58f7..f98f2001f3 100644
--- a/wmake/rules/linuxIcc/c++
+++ b/wmake/rules/linuxIcc/c++
@@ -5,7 +5,9 @@ c++ARCH     = -pthread -fp-trap=common -fp-model precise
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linuxPPC64Gcc/c b/wmake/rules/linuxPPC64Gcc/c
index bc090f98a6..e383499f44 100644
--- a/wmake/rules/linuxPPC64Gcc/c
+++ b/wmake/rules/linuxPPC64Gcc/c
@@ -6,7 +6,9 @@ cARCH       = -m64 -mcpu=power5+
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linuxPPC64Gcc/c++ b/wmake/rules/linuxPPC64Gcc/c++
index 41657aae93..7bc6794119 100644
--- a/wmake/rules/linuxPPC64Gcc/c++
+++ b/wmake/rules/linuxPPC64Gcc/c++
@@ -5,7 +5,9 @@ c++ARCH     = -m64 -mcpu=power5+
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/linuxPPC64leGcc/c b/wmake/rules/linuxPPC64leGcc/c
index 2642a4fbc6..4ec55a67c0 100644
--- a/wmake/rules/linuxPPC64leGcc/c
+++ b/wmake/rules/linuxPPC64leGcc/c
@@ -6,7 +6,9 @@ cARCH       = -m64 -mcpu=power8
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/linuxPPC64leGcc/c++ b/wmake/rules/linuxPPC64leGcc/c++
index 726211d1d4..facaa50a4c 100644
--- a/wmake/rules/linuxPPC64leGcc/c++
+++ b/wmake/rules/linuxPPC64leGcc/c++
@@ -5,7 +5,9 @@ c++ARCH     = -m64 -mcpu=power8
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/rules/solaris64Gcc/c b/wmake/rules/solaris64Gcc/c
index 1997811fb1..61b4b1e089 100644
--- a/wmake/rules/solaris64Gcc/c
+++ b/wmake/rules/solaris64Gcc/c
@@ -6,7 +6,9 @@ cARCH       = -m64
 # Compile option is non-mandatory, but must be non-empty
 sinclude $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
 
-cFLAGS      = $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+cFLAGS      = \
+    $(cARCH) $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) \
+    $(FOAM_EXTRA_CFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
 
diff --git a/wmake/rules/solaris64Gcc/c++ b/wmake/rules/solaris64Gcc/c++
index 0bf17f5dff..cd1c3bd138 100644
--- a/wmake/rules/solaris64Gcc/c++
+++ b/wmake/rules/solaris64Gcc/c++
@@ -5,7 +5,9 @@ c++ARCH     = -m64
 
 include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
 
-c++FLAGS    = $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+c++FLAGS    = \
+    $(c++ARCH) $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) \
+    $(FOAM_EXTRA_CXXFLAGS) $(LIB_HEADER_DIRS) -fPIC
 
 Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
 cctoo       = $(Ctoo)
diff --git a/wmake/scripts/AllwmakeParseArguments b/wmake/scripts/AllwmakeParseArguments
index 80453348c5..6da48e9bf5 100644
--- a/wmake/scripts/AllwmakeParseArguments
+++ b/wmake/scripts/AllwmakeParseArguments
@@ -171,8 +171,8 @@ do
         continue    # Argument handled, remove it
         ;;
 
-    -debug)
-        optDebug="-debug"
+    -debug | -debug-O[0123])
+        optDebug="$arg"
         continue    # Argument handled, remove it
         ;;
 
diff --git a/wmake/wmake b/wmake/wmake
index 349fa96772..a5aead20d9 100755
--- a/wmake/wmake
+++ b/wmake/wmake
@@ -7,7 +7,7 @@
 #    \\/     M anipulation  |
 #------------------------------------------------------------------------------
 #     Copyright (C) 2011-2016 OpenFOAM Foundation
-#     Copyright (C) 2017-2021 OpenCFD Ltd.
+#     Copyright (C) 2017-2022 OpenCFD Ltd.
 #------------------------------------------------------------------------------
 # License
 #     This file is part of OpenFOAM, distributed under GPL-3.0-or-later.
@@ -69,8 +69,9 @@ HELP_HEAD
 if [ -n "$1" ]
 then
 cat<<HELP_FULL
-  -debug            Define c++DBUG='-DFULLDEBUG -g' as override
-  -build-root=PATH  Specify FOAM_BUILDROOT for compilation intermediates
+  -debug            Add '-DFULLDEBUG -g' flags
+  -debug-O[0123]    Add '-DFULLDEBUG -g' flags and optimization level
+  -build-root=PATH      Specify FOAM_BUILDROOT for compilation intermediates
   -module-prefix=PATH   Specify FOAM_MODULE_PREFIX as absolute/relative path
   -module-prefix=TYPE   Specify FOAM_MODULE_PREFIX as predefined type
                         (u,user | g,group | o,openfoam)
@@ -249,8 +250,13 @@ do
             optQuiet=true
             export WM_QUIET=true
             ;;
+
         -debug)
-            optDebug=true
+            optDebug="-g"
+            ;;
+
+        -debug-O[0123])
+            optDebug="-g -${1##*-}"
             ;;
 
         -build-root=*)
@@ -484,8 +490,8 @@ unset exitCode
 
 if [ -n "$optDebug" ]
 then
-    # Convey -debug via FOAM_EXTRA_CXXFLAGS
-    optDebug="-DFULLDEBUG -g"
+    # Add -debug values into FOAM_EXTRA_CXXFLAGS
+    optDebug="-DFULLDEBUG $optDebug"
     oldFlags="$FOAM_EXTRA_CXXFLAGS"
 
     case "$oldFlags" in