Merge pull request #242 in HDFFV/hdf5 from ~DEROBINS/hdf5_der:dev_warnings01 to develop

* commit 'e6a12a3feaa3a111510d899102af77f61950b8bf':
  Added an --enable-developer-warnings option to configure so users can ignore -Wsuggest-attribute warnings and other noise that doesn't indicate poor code quality.

2 files changed, 58 insertions, 24 deletions

diff --git a/config/gnu-flags b/config/gnu-flags
index 0b5283c..c0c8368 100644
--- a/config/gnu-flags
+++ b/config/gnu-flags
@@ -94,7 +94,7 @@ case "$cc_vendor-$cc_version" in
     esac
 
     # General
-    H5_CFLAGS="$H5_CFLAGS $arch -std=c99 -pedantic -Wall -W -Wundef -Wshadow -Wpointer-arith -Wbad-function-cast -Wcast-qual -Wcast-align -Wwrite-strings -Wconversion -Waggregate-return -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wredundant-decls -Wnested-externs -Winline"
+    H5_CFLAGS="$H5_CFLAGS $arch -std=c99 -pedantic -Wall -W -Wundef -Wshadow -Wpointer-arith -Wbad-function-cast -Wcast-qual -Wcast-align -Wwrite-strings -Wconversion -Waggregate-return -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wredundant-decls -Wnested-externs"
 
     # Production
     # NDEBUG is handled explicitly by the configure script
@@ -125,6 +125,10 @@ case "$cc_vendor-$cc_version" in
     esac
     #DEBUG_CFLAGS="-fsanitize=undefined"
 
+    # Developer warnings (suggestions from gcc, not code problems)
+    NO_DEVELOPER_WARNING_CFLAGS="-Wno-suggest-attribute=const -Wno-suggest-attribute=pure -Wno-suggest-attribute=noreturn -Wno-suggest-attribute=format -Wno-inline"
+    DEVELOPER_WARNING_CFLAGS="-Wsuggest-attribute=const -Wsuggest-attribute=pure -Wsuggest-attribute=noreturn -Wsuggest-attribute=format -Winline"
+
     # Symbols
     NO_SYMBOLS_CFLAGS="-s"
     SYMBOLS_CFLAGS="-g"
@@ -223,13 +227,10 @@ case "$cc_vendor-$cc_version" in
     H5_CFLAGS="$H5_CFLAGS -Wstrict-overflow=5 -Wjump-misses-init -Wunsuffixed-float-constants"
 
     # Append more extra warning flags that only gcc 4.6+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wdouble-promotion -Wsuggest-attribute=const -Wtrampolines"
+    H5_CFLAGS="$H5_CFLAGS -Wdouble-promotion -Wtrampolines"
 
     # Append more extra warning flags that only gcc 4.7+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wstack-usage=8192 -Wvector-operation-performance -Wsuggest-attribute=pure -Wsuggest-attribute=noreturn"
-
-    # Append more extra warning flags that only gcc 4.8+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wsuggest-attribute=format"
+    H5_CFLAGS="$H5_CFLAGS -Wstack-usage=8192 -Wvector-operation-performance"
 
     # Append more extra warning flags that only gcc 4.9+ know about
     H5_CFLAGS="$H5_CFLAGS -Wdate-time"
@@ -297,13 +298,10 @@ case "$cc_vendor-$cc_version" in
     H5_CFLAGS="$H5_CFLAGS -Wstrict-overflow=5 -Wjump-misses-init -Wunsuffixed-float-constants"
 
     # Append more extra warning flags that only gcc 4.6+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wdouble-promotion -Wsuggest-attribute=const -Wtrampolines"
+    H5_CFLAGS="$H5_CFLAGS -Wdouble-promotion -Wtrampolines"
 
     # Append more extra warning flags that only gcc 4.7+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wstack-usage=8192 -Wvector-operation-performance -Wsuggest-attribute=pure -Wsuggest-attribute=noreturn"
-
-    # Append more extra warning flags that only gcc 4.8+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wsuggest-attribute=format"
+    H5_CFLAGS="$H5_CFLAGS -Wstack-usage=8192 -Wvector-operation-performance"
 
     # Append more extra warning flags that only gcc 4.9+ know about
     H5_CFLAGS="$H5_CFLAGS -Wdate-time"
@@ -368,13 +366,10 @@ case "$cc_vendor-$cc_version" in
     H5_CFLAGS="$H5_CFLAGS -Wstrict-overflow=5 -Wjump-misses-init -Wunsuffixed-float-constants"
 
     # Append more extra warning flags that only gcc 4.6+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wdouble-promotion -Wsuggest-attribute=const -Wtrampolines"
+    H5_CFLAGS="$H5_CFLAGS -Wdouble-promotion -Wtrampolines"
 
     # Append more extra warning flags that only gcc 4.7+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wstack-usage=8192 -Wvector-operation-performance -Wsuggest-attribute=pure -Wsuggest-attribute=noreturn"
-
-    # Append more extra warning flags that only gcc 4.8+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wsuggest-attribute=format"
+    H5_CFLAGS="$H5_CFLAGS -Wstack-usage=8192 -Wvector-operation-performance"
 
     # Append more extra warning flags that only gcc 4.9+ know about
     H5_CFLAGS="$H5_CFLAGS -Wdate-time"
@@ -436,13 +431,10 @@ case "$cc_vendor-$cc_version" in
     H5_CFLAGS="$H5_CFLAGS -Wstrict-overflow=5 -Wjump-misses-init"
 
     # Append more extra warning flags that only gcc 4.6+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wdouble-promotion -Wsuggest-attribute=const -Wtrampolines"
+    H5_CFLAGS="$H5_CFLAGS -Wdouble-promotion -Wtrampolines"
 
     # Append more extra warning flags that only gcc 4.7+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wstack-usage=8192 -Wvector-operation-performance -Wsuggest-attribute=pure -Wsuggest-attribute=noreturn"
-
-    # Append more extra warning flags that only gcc 4.8+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wsuggest-attribute=format"
+    H5_CFLAGS="$H5_CFLAGS -Wstack-usage=8192 -Wvector-operation-performance"
     ;;
 
   gcc-4.7*)
@@ -502,10 +494,10 @@ case "$cc_vendor-$cc_version" in
     H5_CFLAGS="$H5_CFLAGS -Wstrict-overflow=5 -Wjump-misses-init -Wunsuffixed-float-constants"
 
     # Append more extra warning flags that only gcc 4.6+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wdouble-promotion -Wsuggest-attribute=const -Wtrampolines"
+    H5_CFLAGS="$H5_CFLAGS -Wdouble-promotion -Wtrampolines"
 
     # Append more extra warning flags that only gcc 4.7+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wstack-usage=8192 -Wvector-operation-performance -Wsuggest-attribute=pure -Wsuggest-attribute=noreturn"
+    H5_CFLAGS="$H5_CFLAGS -Wstack-usage=8192 -Wvector-operation-performance"
     ;;
 
   gcc-4.6*)
@@ -561,7 +553,7 @@ case "$cc_vendor-$cc_version" in
     H5_CFLAGS="$H5_CFLAGS -Wstrict-aliasing -Wstrict-overflow=5 -Wjump-misses-init -Wunsuffixed-float-constants"
 
     # Append more extra warning flags that only gcc 4.6+ know about
-    H5_CFLAGS="$H5_CFLAGS -Wdouble-promotion -Wsuggest-attribute=const -Wtrampolines"
+    H5_CFLAGS="$H5_CFLAGS -Wdouble-promotion -Wtrampolines"
     ;;
 
   gcc-4.5*)
diff --git a/configure.ac b/configure.ac
index 82ad020..9f84b0f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2055,6 +2055,48 @@ case "X-$ASSERTS" in
 esac
 
 ## ----------------------------------------------------------------------
+## Check if developer warnings should be turned on
+## These are warnings that provide suggestions like gcc's -Wsuggest-attribute.
+## They do not indicate code problems.
+##
+## Note that developers don't need to build with these regularly. They
+## are just handy to check once in a while (before releases, etc.).
+##
+AC_MSG_CHECKING([enable developer warnings])
+AC_ARG_ENABLE([developer-warnings],
+              [AS_HELP_STRING([--enable-developer-warnings],
+                              [Determines whether developer warnings will be
+                               emitted. These are usually performance suggestions
+                               (e.g. -Wsuggest-attribute) and do not flag poor code
+                               quality.
+                               [default=no]
+                               ])],
+              [DEV_WARNINGS=$enableval])
+
+## Set default
+if test "X-$DEV_WARNINGS" = X- ; then
+  DEV_WARNINGS=no
+fi
+
+## Allow this variable to be substituted in
+## other files (src/libhdf5.settings.in, etc.)
+AC_SUBST([DEV_WARNINGS])
+
+case "X-$DEV_WARNINGS" in
+  X-yes)
+    H5_CFLAGS="$H5_CFLAGS $DEVELOPER_WARNING_CFLAGS"
+    AC_MSG_RESULT([yes])
+    ;;
+  X-no)
+    H5_CFLAGS="$H5_CFLAGS $NO_DEVELOPER_WARNING_CFLAGS"
+    AC_MSG_RESULT([no])
+    ;;
+  *)
+    AC_MSG_ERROR([Unrecognized value: $DEV_WARNINGS])
+    ;;
+esac
+
+## ----------------------------------------------------------------------
 ## Check if the compiler should use profiling flags/settings
 ##
 AC_MSG_CHECKING([profiling])