Break out warnings into more files that autoconf and CMake can share. This

change temporarily disables the warnings that were promoted to errors, but I
will add those warnings back as warnings, not errors, in the next commit.

config/gnu-flags

@@ -171,35 +171,13 @@ if test "X-gcc" = "X-$cc_vendor"; then
     # General #
     ###########
 
-    # Note that some of the flags listed here really should be developer
-    # flags (listed in a separate variable, below) but we put them here
-    # because they are not raised by the current code and we'd like to
-    # know if they do start showing up.
-    #
-    # NOTE: Don't add -Wpadded here since we can't/won't fix the (many)
-    # warnings that are emitted. If you need it, add it from the
-    # environment variable at configure time.
-    #
-    # NOTE: Disable the -Wformat-nonliteral from -Wformat=2 here and re-add
-    # it to the developer flags.
-    #
-    # NOTE: Due to the divergence in the C and C++, we're dropping support for
-    # compiling the C library with a C++ compiler and dropping the -Wc++-compat
-    # warning.
     H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-general)"
-    H5_CFLAGS="$H5_CFLAGS -Wbad-function-cast -Wcast-align"
-    H5_CFLAGS="$H5_CFLAGS -Wdeclaration-after-statement -Wdisabled-optimization"
-    H5_CFLAGS="$H5_CFLAGS -Wmissing-declarations"
-    H5_CFLAGS="$H5_CFLAGS -Wmissing-prototypes -Wnested-externs -Wold-style-definition -Wpacked"
-    H5_CFLAGS="$H5_CFLAGS -Wredundant-decls -Wstrict-prototypes -Wswitch-enum -Wswitch-default"
-    H5_CFLAGS="$H5_CFLAGS -Wunused-macros -Wunsafe-loop-optimizations"
+    H5_ECFLAGS="$H5_ECFLAGS $(load_gcc_arguments werrors-general)"
 
     ######################
     # Developer warnings #
     ######################
 
-    # (suggestions from gcc, not code problems)
-    # NOTE: -Wformat-nonliteral added back in here (from being disabled in H5_CFLAGS)
     NO_DEVELOPER_WARNING_CFLAGS=$(load_gcc_arguments warnings-no-developer-general)
     DEVELOPER_WARNING_CFLAGS=$(load_gcc_arguments warnings-developer-general)
 
@@ -207,106 +185,106 @@ if test "X-gcc" = "X-$cc_vendor"; then
     # gcc 4 special cases #
     #######################
 
-    # Disable warnings about using the 'long long' type w/ gcc 4.6 and earlier
+    # GCC 4.2 through 4.6
     if test $cc_vers_major -eq 4 -a $cc_vers_minor -ge 2 -o $cc_vers_major -eq 4 -a $cc_vers_minor -le 6; then
-        H5_CFLAGS="$H5_CFLAGS -Wno-long-long"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-4.2-4.6)"
     fi
 
-    # -Wvolatile-register-var was later incorporated into -Wall and
-    # only needs to be specified explicitly for gcc 4.2-4.3
+    # GCC 4.2 through 4.3
     if test $cc_vers_major -eq 4 -a $cc_vers_minor -ge 2 -o $cc_vers_major -eq 4 -a $cc_vers_minor -le 3; then
-        H5_CFLAGS="$H5_CFLAGS -Wvolatile-register-var"
-    fi
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-4.2-4.3)"
+    fi 
 
-    # -Wstrict-aliasing was later incorporated into -Wall and
-    # only needs to be specified explicitly for gcc 4.5-4.6
+    # GCC 4.5 through 4.6
     if test $cc_vers_major -eq 4 -a $cc_vers_minor -ge 5 -o $cc_vers_major -eq 4 -a $cc_vers_minor -le 6; then
-        H5_CFLAGS="$H5_CFLAGS -Wstrict-aliasing"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-4.5-4.6)"
     fi
 
-    # The non-valued form of -Wstrict-overflow is used in gcc 4.2-4.4
+    # GCC 4.2 through 4.4
     if test $cc_vers_major -eq 4 -a $cc_vers_minor -ge 2 -a $cc_vers_major -eq 4 -a $cc_vers_minor -le 4; then
-        H5_CFLAGS="$H5_CFLAGS -Wstrict-overflow"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-4.2-4.4)"
     fi
 
-    # -Wvla was later incorporated into -Wpedantic and
-    # only needs to be specified explicitly for gcc 4
+    # GCC 4.2 through the end of GCC 4 series
     if test $cc_vers_major -eq 4 -a $cc_vers_minor -ge 2; then
-        H5_CFLAGS="$H5_CFLAGS -Wvla"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-4.2-4.last)"
     fi
 
     #############################
     # Version-specific warnings #
     #############################
 
-    # gcc 4.3
+    # gcc >= 4.3
     if test $cc_vers_major -ge 5 -o $cc_vers_major -eq 4 -a $cc_vers_minor -ge 3; then
-        H5_CFLAGS="$H5_CFLAGS -Wlogical-op -Wlarger-than=2560"
-    fi
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-4.3)"
+    fi 
 
-    # gcc 4.4
+    # gcc >= 4.4
     if test $cc_vers_major -ge 5 -o $cc_vers_major -eq 4 -a $cc_vers_minor -ge 4; then
-        H5_CFLAGS="$H5_CFLAGS -Wsync-nand -Wframe-larger-than=16384 -Wpacked-bitfield-compat"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-4.4)"
     fi
 
-    # gcc 4.5
+    # gcc >= 4.5
     if test $cc_vers_major -ge 5 -o $cc_vers_major -eq 4 -a $cc_vers_minor -ge 5; then
-        H5_CFLAGS="$H5_CFLAGS -Wstrict-overflow=5 -Wjump-misses-init"
-        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wunsuffixed-float-constants"
-        NO_DEVELOPER_WARNING_CFLAGS="$NO_DEVELOPER_WARNING_CFLAGS -Wno-unsuffixed-float-constants"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-4.5)"
+	DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS $(load_gcc_arguments warnings-developer-4.5)"
+	NO_DEVELOPER_WARNING_CFLAGS="$NO_DEVELOPER_WARNING_CFLAGS $(load_gcc_arguments warnings-no-developer-4.5)"
     fi
 
-    # gcc 4.6
+    # gcc >= 4.6
     if test $cc_vers_major -ge 5 -o $cc_vers_major -eq 4 -a $cc_vers_minor -ge 6; then
-        H5_CFLAGS="$H5_CFLAGS -Wdouble-promotion -Wtrampolines"
-        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wsuggest-attribute=const"
-        NO_DEVELOPER_WARNING_CFLAGS="$NO_DEVELOPER_WARNING_CFLAGS -Wno-suggest-attribute=const"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-4.6)"
+	DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS $(load_gcc_arguments warnings-developer-4.6)"
+	NO_DEVELOPER_WARNING_CFLAGS="$NO_DEVELOPER_WARNING_CFLAGS $(load_gcc_arguments warnings-no-developer-4.6)"
     fi
 
-    # gcc 4.7
+    # gcc >= 4.7
     if test $cc_vers_major -ge 5 -o $cc_vers_major -eq 4 -a $cc_vers_minor -ge 7; then
-        H5_CFLAGS="$H5_CFLAGS -Wstack-usage=8192 -Wvector-operation-performance"
-        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wsuggest-attribute=pure -Wsuggest-attribute=noreturn"
-        NO_DEVELOPER_WARNING_CFLAGS="$NO_DEVELOPER_WARNING_CFLAGS -Wno-suggest-attribute=pure -Wno-suggest-attribute=noreturn"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-4.7)"
+	DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS $(load_gcc_arguments warnings-developer-4.7)"
+	NO_DEVELOPER_WARNING_CFLAGS="$NO_DEVELOPER_WARNING_CFLAGS $(load_gcc_arguments warnings-no-developer-4.7)"
     fi
 
-    # gcc 4.8
+    # gcc >= 4.8
     if test $cc_vers_major -ge 5 -o $cc_vers_major -eq 4 -a $cc_vers_minor -ge 8; then
-        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wsuggest-attribute=format"
-        NO_DEVELOPER_WARNING_CFLAGS="$NO_DEVELOPER_WARNING_CFLAGS -Wno-suggest-attribute=format"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-4.8)"
+	DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS $(load_gcc_arguments warnings-developer-4.8)"
+	NO_DEVELOPER_WARNING_CFLAGS="$NO_DEVELOPER_WARNING_CFLAGS $(load_gcc_arguments warnings-no-developer-4.8)"
     fi
 
-    # gcc 4.9
+    # gcc >= 4.9
     if test $cc_vers_major -ge 5 -o $cc_vers_major -eq 4 -a $cc_vers_minor -ge 9; then
-        H5_CFLAGS="$H5_CFLAGS -Wdate-time"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-4.9)"
     fi
 
-    # gcc 5
+    # gcc >= 5
     if test $cc_vers_major -ge 5; then
-        H5_CFLAGS="$H5_CFLAGS -Warray-bounds=2 -Wc99-c11-compat"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-5)"
+        H5_ECFLAGS="$H5_ECFLAGS $(load_gcc_arguments werrors-5)"
     fi
 
-    # gcc 6
+    # gcc >= 6
     if test $cc_vers_major -ge 6; then
-        H5_CFLAGS="$H5_CFLAGS -Wnull-dereference -Wunused-const-variable -Wduplicated-cond -Whsa -Wnormalized"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-6)"
     fi
 
-    # gcc 7
+    # gcc >= 7
     if test $cc_vers_major -ge 7; then
-        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wstringop-overflow=2"
-        H5_CFLAGS="$H5_CFLAGS -Walloc-zero -Walloca -Wduplicated-branches -Wformat-overflow=2 -Wformat-truncation=1 -Wimplicit-fallthrough=5 -Wrestrict"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-7)"
+	DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS $(load_gcc_arguments warnings-developer-7)"
     fi
 
     # gcc 8
     if test $cc_vers_major -ge 8; then
-        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wstringop-overflow=4 -Wsuggest-attribute=cold -Wsuggest-attribute=malloc"
-        NO_DEVELOPER_WARNING_CFLAGS="$NO_DEVELOPER_WARNING_CFLAGS -Wno-suggest-attribute=cold -Wno-suggest-attribute=malloc"
-        H5_CFLAGS="$H5_CFLAGS -Wattribute-alias -Wcast-align=strict -Wshift-overflow=2"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-8)"
+        H5_ECFLAGS="$H5_ECFLAGS $(load_gcc_arguments werrors-8)"
+	DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS $(load_gcc_arguments warnings-developer-8)"
+	NO_DEVELOPER_WARNING_CFLAGS="$NO_DEVELOPER_WARNING_CFLAGS $(load_gcc_arguments warnings-no-developer-8)"
     fi
 
     # gcc 9
     if test $cc_vers_major -ge 9; then
-        H5_CFLAGS="$H5_CFLAGS -Wattribute-alias=2 -Wmissing-profile"
+        H5_CFLAGS="$H5_CFLAGS $(load_gcc_arguments warnings-9)"
     fi
 
     #################

config/gnu-warnings-4.2-4.3

@@ -0,0 +1,3 @@
+# -Wvolatile-register-var was later incorporated into -Wall and
+# only needs to be specified explicitly for gcc 4.2-4.3
+-Wvolatile-register-var

config/gnu-warnings-4.2-4.4

@@ -0,0 +1,2 @@
+# The non-valued form of -Wstrict-overflow is used in gcc 4.2-4.4
+-Wstrict-overflow

config/gnu-warnings-4.2-4.6

@@ -0,0 +1,2 @@
+# Disable warnings about using the 'long long' type w/ gcc 4.6 and earlier
+-Wno-long-long

config/gnu-warnings-4.2-4.last

@@ -0,0 +1,3 @@
+# -Wvla was later incorporated into -Wpedantic and
+# only needs to be specified explicitly for gcc 4
+-Wvla

config/gnu-warnings-4.3

@@ -0,0 +1,2 @@
+-Wlarger-than=2560
+-Wlogical-op

config/gnu-warnings-4.4

@@ -0,0 +1,3 @@
+-Wframe-larger-than=16384
+-Wpacked-bitfield-compat
+-Wsync-nand

config/gnu-warnings-4.5

@@ -0,0 +1 @@
+-Wstrict-overflow=5

config/gnu-warnings-4.5-4.6

@@ -0,0 +1,3 @@
+# -Wstrict-aliasing was later incorporated into -Wall and
+# only needs to be specified explicitly for gcc 4.5-4.6
+-Wstrict-aliasing

config/gnu-warnings-4.6

@@ -0,0 +1,2 @@
+-Wdouble-promotion
+-Wtrampolines

config/gnu-warnings-4.7

@@ -0,0 +1,5 @@
+#
+# -Wstack-usage=8192 warnings need to be swept up on a branch so
+# that we can stop burdening the whole development team.
+#
+-Wstack-usage=8192

config/gnu-warnings-4.8

@@ -0,0 +1 @@
+-Wmaybe-uninitialized

config/gnu-warnings-4.9

@@ -0,0 +1 @@
+-Wdate-time

config/gnu-warnings-5

@@ -0,0 +1,2 @@
+-Warray-bounds=2
+-Wc99-c11-compat

config/gnu-warnings-6

@@ -0,0 +1,9 @@
+#
+# Careful!  -Wduplicated-cond, combined with HDF5's heavy use of
+# macros, can make a lot of noise.
+#
+-Wduplicated-cond
+-Whsa
+-Wnormalized
+-Wnull-dereference
+-Wunused-const-variable

config/gnu-warnings-7

@@ -0,0 +1,7 @@
+-Walloca
+-Walloc-zero
+-Wduplicated-branches
+-Wformat-overflow=2
+-Wformat-truncation=1
+-Wimplicit-fallthrough=5
+-Wrestrict

config/gnu-warnings-8

@@ -0,0 +1,3 @@
+-Wattribute-alias
+-Wcast-align=strict
+-Wshift-overflow=2

config/gnu-warnings-9

@@ -0,0 +1,2 @@
+-Wattribute-alias=2
+-Wmissing-profile

config/gnu-warnings-developer-4.5

@@ -0,0 +1,7 @@
+#
+# -Wjump-misses-init makes lots of noise for a questionable benefit.
+# Can jumping over an initialization in C cause any harm, if
+# the variable is never *used* before it has been initialized?
+#
+-Wjump-misses-init
+-Wunsuffixed-float-constants

config/gnu-warnings-developer-4.6

@@ -0,0 +1 @@
+-Wsuggest-attribute=const

config/gnu-warnings-developer-4.7

@@ -0,0 +1,7 @@
+-Wsuggest-attribute=noreturn
+-Wsuggest-attribute=pure
+#
+# It's not clear that -Wvector-operation-performance warnings are
+# actionable, so they are demoted to "developer" warnings.
+#
+-Wvector-operation-performance

config/gnu-warnings-developer-4.8

@@ -0,0 +1 @@
+-Wsuggest-attribute=format

config/gnu-warnings-developer-7

@@ -0,0 +1 @@
+-Wstringop-overflow=2

config/gnu-warnings-developer-8

@@ -0,0 +1,3 @@
+-Wstringop-overflow=4
+-Wsuggest-attribute=cold
+-Wsuggest-attribute=malloc

config/gnu-warnings-developer-general

@@ -2,7 +2,12 @@
 # NOTE: -Wformat-nonliteral added back in here (from being disabled in
 # H5_CFLAGS)
 -Waggregate-return
+-Wdisabled-optimization
 -Wformat-nonliteral
 -Winline
 -Wmissing-format-attribute
 -Wmissing-noreturn
+-Wswitch-default
+-Wswitch-enum
+-Wunsafe-loop-optimizations
+-Wunused-macros

config/gnu-warnings-general

@@ -29,4 +29,4 @@
 -Wshadow
 -Wundef
 -Wwrite-strings
--pedantic
+-pedantic

config/gnu-warnings-no-developer-4.5

@@ -0,0 +1 @@
+-Wno-unsuffixed-float-constants

config/gnu-warnings-no-developer-4.6

@@ -0,0 +1 @@
+-Wno-suggest-attribute=const

config/gnu-warnings-no-developer-4.7

@@ -0,0 +1,2 @@
+-Wno-suggest-attribute=noreturn
+-Wno-suggest-attribute=pure

config/gnu-warnings-no-developer-4.8

@@ -0,0 +1 @@
+-Wno-suggest-attribute=format

config/gnu-warnings-no-developer-8

@@ -0,0 +1,2 @@
+-Wno-suggest-attribute=cold
+-Wno-suggest-attribute=malloc

config/gnu-werrors-5

@@ -0,0 +1,12 @@
+-Werror=incompatible-pointer-types
+#
+# In GCC 4.4.7, the compiler gripes about shadowed global
+# declarations when a local variable uses the name of a
+# function that's in a system header file.  For some reason,
+# later versions of GCC (e.g., 5.2.0) don't complain about
+# the shadowed globals.  Maybe later versions are less fussy?
+# Anyway, the shadowing seems to be harmless, and GCC 4.4.7
+# is not a supported compiler, so let us promote shadowed globals
+# warnings to errors only for GCC 5 and later.
+#
+-Werror=shadow

config/gnu-werrors-8

@@ -0,0 +1,9 @@
+-Werror=cast-function-type
+#
+# For GCC 8, promote maybe-initialized warnings to an error.  GCC 8
+# reports 0 maybe-uninitialized warnings where earlier versions
+# make many false reports.  GCC 8 seems to analyze calls to static
+# in order to detect initializations that occur there.  It's possible
+# that GCC 8 only performs that analysis at -O3, though.
+#
+-Werror=maybe-uninitialized

config/gnu-werrors-general

@@ -0,0 +1,24 @@
+#
+# HDF5 code should not trigger the following warnings under any
+# circumstances, so ask the compiler to treat them as errors:
+#
+-Werror=bad-function-cast
+-Werror=cast-align
+-Werror=declaration-after-statement
+-Werror=format
+-Werror=implicit-function-declaration
+-Werror=missing-declarations
+-Werror=missing-prototypes
+-Werror=nested-externs
+-Werror=old-style-definition
+-Werror=packed
+-Werror=pointer-sign
+-Werror=pointer-to-int-cast
+-Werror=redundant-decls
+-Werror=strict-prototypes
+-Werror=switch
+-Werror=unused-but-set-variable
+-Werror=unused-function
+-Werror=unused-parameter
+-Werror=unused-variable
+#-Werror=discarded-qualifiers