Add a new variable: GNUMAKEFLAGS

This allows you to write portable makefiles that set GNU make-specific command
line options in the environment or makefile: add them to GNUMAKEFLAGS instead
of MAKEFLAGS and they will be seen by GNU make but ignored by other
implementations of make.

5 files changed, 62 insertions, 6 deletions

diff --git a/NEWS b/NEWS
index 621be57..2ecd66f 100644
--- a/NEWS
+++ b/NEWS
@@ -23,12 +23,6 @@ http://sv.gnu.org/bugs/index.php?group=make&report_id=111&fix_release_id=101&set
   * Each backslash/newline (plus subsequent whitespace) is converted to a
     single space
 
-* New command line option: --trace enables tracing of targets.  When enabled
-  the recipe to be invoked is printed even if it would otherwise be suppressed
-  by .SILENT or a "@" prefix character.  Also before each recipe is run the
-  makefile name and linenumber where it was defined are shown as well as the
-  prerequisites that caused the target to be considered out of date.
-
 * New command line option: --output-sync (-O) enables grouping of output by
   target or by recursive make.  This is useful during parallel builds to avoid
   mixing output from different jobs together giving hard-to-understand
@@ -36,6 +30,14 @@ http://sv.gnu.org/bugs/index.php?group=make&report_id=111&fix_release_id=101&set
   Reworked and enhanced by Frank Heckenbach <f.heckenbach@fh-soft.de>.
   Windows support by Eli Zaretskii <eliz@gnu.org>.
 
+* New command line option: --trace enables tracing of targets.  When enabled
+  the recipe to be invoked is printed even if it would otherwise be suppressed
+  by .SILENT or a "@" prefix character.  Also before each recipe is run the
+  makefile name and linenumber where it was defined are shown as well as the
+  prerequisites that caused the target to be considered out of date.  If the
+  "dir" option argument is given, it will display directory enter/leave
+  logging around each block of synchronized output.
+
 * New feature: The "job server" capability is now supported on Windows.
   Implementation contributed by Troy Runkel <Troy.Runkel@mathworks.com>
 
@@ -67,6 +69,11 @@ http://sv.gnu.org/bugs/index.php?group=make&report_id=111&fix_release_id=101&set
 
 * New function: $(file ...) writes to a file.
 
+* New variable: $(GNUMAKEFLAGS) will be parsed for make flags, just like
+  MAKEFLAGS is.  It can be set in the environment or the makefile, containing
+  GNU make-specific flags to allow your makefile to be portable to other
+  versions of make.  GNU make never sets or modifies GNUMAKEFLAGS.
+
 * On failure, the makefile name and linenumber of the recipe that failed are
   shown.
 
diff --git a/default.c b/default.c
index 9f02dd4..4b24e2e 100644
--- a/default.c
+++ b/default.c
@@ -525,6 +525,8 @@ static const char *default_variables[] =
 #endif
 
 #endif /* !VMS */
+    /* Make this assignment to avoid undefined variable warnings.  */
+    "GNUMAKEFLAGS", "",
     0, 0
   };
 
diff --git a/doc/make.texi b/doc/make.texi
index 8a35780..e3e5135 100644
--- a/doc/make.texi
+++ b/doc/make.texi
@@ -4798,6 +4798,16 @@ itself.  For instance, the @samp{-t}, @samp{-n}, and @samp{-q} options, if
 put in one of these variables, could have disastrous consequences and would
 certainly have at least surprising and probably annoying effects.@refill
 
+If you'd like to run other implementations of @code{make} in addition
+to GNU @code{make}, and hence do not want to add GNU
+@code{make}-specific flags to the @code{MAKEFLAGS} variable, you can
+add them to the @code{GNUMAKEFLAGS} variable instead.  This variable
+is parsed just before @code{MAKEFLAGS}, in the same way as
+@code{MAKEFLAGS}.  Note, however, that when @code{make} constructs
+@code{MAKEFLAGS} to pass to a recursive @code{make} it will include
+all flags.  GNU @code{make} never sets the @code{GNUMAKEFLAGS}
+variable itself.
+
 @node -w Option,  , Options/Recursion, Recursion
 @subsection The @samp{--print-directory} Option
 @cindex directories, printing them
@@ -11968,6 +11978,16 @@ recipe line: its contents may not be quoted correctly for use in the
 shell.  Always allow recursive @code{make}'s to obtain these values
 through the environment from its parent.
 
+@item GNUMAKEFLAGS
+
+Other flags parsed by @code{make}.  You can set this in the environment or
+a makefile to set @code{make} command-line flags.  GNU @code{make}
+never sets this variable itself.  This variable is only needed if
+you'd like to set GNU @code{make}-specific flags in a POSIX-compliant
+makefile.  This variable will be seen by GNU @code{make} and ignored
+by other @code{make} implementations.  It's not needed if you only use
+GNU @code{make}; just use @code{MAKEFLAGS} directly.
+
 @item MAKECMDGOALS
 
 The targets given to @code{make} on the command line.  Setting this
diff --git a/main.c b/main.c
index f3c4a3d..8eed56d 100644
--- a/main.c
+++ b/main.c
@@ -1339,7 +1339,9 @@ main (int argc, char **argv, char **envp)
 
   /* Decode the switches.  */
 
+  decode_env_switches (STRING_SIZE_TUPLE ("GNUMAKEFLAGS"));
   decode_env_switches (STRING_SIZE_TUPLE ("MAKEFLAGS"));
+
 #if 0
   /* People write things like:
         MFLAGS="CC=gcc -pipe" "CFLAGS=-g"
@@ -1766,6 +1768,7 @@ main (int argc, char **argv, char **envp)
 #endif /* __MSDOS__ || __EMX__ */
 
   /* Decode switches again, in case the variables were set by the makefile.  */
+  decode_env_switches (STRING_SIZE_TUPLE ("GNUMAKEFLAGS"));
   decode_env_switches (STRING_SIZE_TUPLE ("MAKEFLAGS"));
 #if 0
   decode_env_switches (STRING_SIZE_TUPLE ("MFLAGS"));
diff --git a/tests/scripts/variables/GNUMAKEFLAGS b/tests/scripts/variables/GNUMAKEFLAGS
new file mode 100644
index 0000000..7bfd822
--- /dev/null
+++ b/tests/scripts/variables/GNUMAKEFLAGS
@@ -0,0 +1,24 @@
+#                                                                    -*-perl-*-
+
+$description = "Test proper behavior of GNUMAKEFLAGS";
+
+# Accept flags from GNUMAKEFLAGS as well as MAKEFLAGS
+# Results always go in MAKEFLAGS
+
+$extraENV{'GNUMAKEFLAGS'} = '-e -r -R';
+
+run_make_test(q!
+all: ; @echo $(MAKEFLAGS)
+!,
+              '', 'Rre');
+
+# Long arguments mean everything is prefixed with "-"
+
+$extraENV{'GNUMAKEFLAGS'} = '--no-print-directory -e -r -R --trace=none --trace=dir';
+
+run_make_test(q!
+all: ; @echo $(MAKEFLAGS)
+!,
+              '', '--no-print-directory --trace=none --trace=dir --trace=none --trace=dir -Rre');
+
+1;