ax_compiler_flags: Eliminate ‘minimum’ and ‘maximum’ warning levels

These went against the whole concept of providing a baseline set of
warnings which is set by the module maintainer, since it allowed
individual developers to opt out of certain classes of warning.

Remove them, leaving the ‘no’, ‘yes’ and ‘error’ levels. This maintains
API compatibility of the macros by marking various EXTRA-* variables as
unused, but still handling them, and merging their values with the
preceding EXTRA-* variables. For example, all extra ‘maximum’ and
‘error’ flags are now included in the ‘yes’ level of warnings.

1 files changed, 22 insertions, 19 deletions

diff --git a/m4/ax_compiler_flags.m4 b/m4/ax_compiler_flags.m4
index 34723cc..c52ae7d 100644
--- a/m4/ax_compiler_flags.m4
+++ b/m4/ax_compiler_flags.m4
@@ -4,7 +4,7 @@
 #
 # SYNOPSIS
 #
-#   AX_COMPILER_FLAGS([CFLAGS-VARIABLE], [LDFLAGS-VARIABLE], [IS-RELEASE], [EXTRA-BASE-CFLAGS], [EXTRA-MINIMUM-CFLAGS], [EXTRA-YES-CFLAGS], [EXTRA-MAXIMUM-CFLAGS], [EXTRA-ERROR-CFLAGS], [EXTRA-BASE-LDFLAGS], [EXTRA-MINIMUM-LDFLAGS], [EXTRA-YES-LDFLAGS], [EXTRA-MAXIMUM-LDFLAGS], [EXTRA-ERROR-LDFLAGS])
+#   AX_COMPILER_FLAGS([CFLAGS-VARIABLE], [LDFLAGS-VARIABLE], [IS-RELEASE], [EXTRA-BASE-CFLAGS], [EXTRA-YES-CFLAGS], [UNUSED], [UNUSED], [UNUSED], [EXTRA-BASE-LDFLAGS], [EXTRA-YES-LDFLAGS], [UNUSED], [UNUSED], [UNUSED])
 #
 # DESCRIPTION
 #
@@ -32,21 +32,20 @@
 #   --enable-compile-warnings can take the values:
 #
 #    * no:      Base compiler warnings only; not even -Wall.
-#    * minimum: The above, plus minimal extra warnings such as -Wall.
 #    * yes:     The above, plus a broad range of useful warnings.
-#    * maximum: The above, plus additional warnings which enforce a particular
-#               coding style
 #    * error:   The above, plus -Werror so that all warnings are fatal.
 #               Use --disable-Werror to override this and disable fatal
 #               warnings.
 #
-#   The set of flags enabled at each level can be augmented using the
-#   EXTRA-*-CFLAGS and EXTRA-*-LDFLAGS variables.  Flags should not be
-#   disabled using these arguments, as the entire point of AX_COMPILER_FLAGS
-#   is to enforce a consistent set of useful compiler warnings on code,
-#   using warnings which have been chosen for low false positive rates.  If
-#   a compiler emits false positives for a warning, a #pragma should be used
-#   in the code to disable the warning locally. See:
+#   The set of base and enabled flags can be augmented using the
+#   EXTRA-*-CFLAGS and EXTRA-*-LDFLAGS variables, which are tested and
+#   appended to the output variable if --enable-compile-warnings is not
+#   "no". Flags should not be disabled using these arguments, as the entire
+#   point of AX_COMPILER_FLAGS is to enforce a consistent set of useful
+#   compiler warnings on code, using warnings which have been chosen for low
+#   false positive rates.  If a compiler emits false positives for a
+#   warning, a #pragma should be used in the code to disable the warning
+#   locally. See:
 #
 #     https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/Diagnostic-Pragmas.html#Diagnostic-Pragmas
 #
@@ -73,7 +72,7 @@
 #   before this macro in configure.ac, warning flags for the C++ compiler
 #   are AC_SUBST-ed as WARN_CXXFLAGS, and must be manually added to the
 #   CXXFLAGS variables for each target in the code base.  EXTRA-*-CFLAGS can
-#   be used to augment the flags enabled at each level.
+#   be used to augment the base and enabled flags.
 #
 #   Warning flags for g-ir-scanner (from GObject Introspection) are
 #   AC_SUBST-ed as WARN_SCANNERFLAGS.  This variable must be manually added
@@ -88,6 +87,10 @@
 #   over the flags for individual tools, use AX_COMPILER_FLAGS_CFLAGS,
 #   AX_COMPILER_FLAGS_LDFLAGS and AX_COMPILER_FLAGS_* for new tools.
 #
+#   The UNUSED variables date from a previous version of this macro, and are
+#   automatically appended to the preceding non-UNUSED variable. They should
+#   be left empty in new uses of the macro.
+#
 # LICENSE
 #
 #   Copyright (c) 2014, 2015 Philip Withnall <philip@tecnocode.co.uk>
@@ -98,7 +101,7 @@
 #   and this notice are preserved.  This file is offered as-is, without any
 #   warranty.
 
-#serial 11
+#serial 12
 
 # _AX_COMPILER_FLAGS_LANG([LANGNAME])
 m4_defun([_AX_COMPILER_FLAGS_LANG],
@@ -125,8 +128,8 @@ AC_DEFUN([AX_COMPILER_FLAGS],[
                                                                 [$3])))
 
     AC_ARG_ENABLE([compile-warnings],
-                  AS_HELP_STRING([--enable-compile-warnings=@<:@no/minimum/yes/maximum/error@:>@],
-                                 [Enable different levels of compiler warnings]),,
+                  AS_HELP_STRING([--enable-compile-warnings=@<:@no/yes/error@:>@],
+                                 [Enable compiler warnings and errors]),,
                   [AS_IF([test "$ax_compiler_flags_is_release" = "yes"],
                          [enable_compile_warnings="yes"],
                          [enable_compile_warnings="error"])])
@@ -138,18 +141,18 @@ AC_DEFUN([AX_COMPILER_FLAGS],[
     # Return the user’s chosen warning level
     AS_IF([test "$enable_Werror" = "no" -a \
                 "$enable_compile_warnings" = "error"],[
-        enable_compile_warnings="maximum"
+        enable_compile_warnings="yes"
     ])
 
     ax_enable_compile_warnings=$enable_compile_warnings
 
     AX_COMPILER_FLAGS_CFLAGS([$1],[$ax_compiler_flags_is_release],
-                             [$4],[$5],[$6],[$7],[$8])
+                             [$4],[$5 $6 $7 $8])
     m4_ifdef([_AX_COMPILER_FLAGS_LANG_CXX_enabled],
              [AX_COMPILER_FLAGS_CXXFLAGS([WARN_CXXFLAGS],
                                          [$ax_compiler_flags_is_release],
-                                         [$4],[$5],[$6],[$7],[$8])])
+                                         [$4],[$5 $6 $7 $8])])
     AX_COMPILER_FLAGS_LDFLAGS([$2],[$ax_compiler_flags_is_release],
-                              [$9],[$10],[$11],[$12],[$13])
+                              [$9],[$10 $11 $12 $13])
     AX_COMPILER_FLAGS_GIR([WARN_SCANNERFLAGS],[$ax_compiler_flags_is_release])
 ])dnl AX_COMPILER_FLAGS