Paul, I just tried 3.81.91 with the same build environment as before, and everything builds successfully.

"make check" yields a couple of anomalies, however:

targets/ONESHELL ........................................ ok     (5 passed)
targets/PHONY ........................................... ok     (1 passed)
targets/POSIX ........................................... Error running /tmp/make-3.81.91/__build__/tests/../make (expected 512; got 0): /tmp/make-3.81.91/__build__/tests/../make -f work/targets/POSIX.mk
FAILED (0/2 passed)
targets/SECONDARY ....................................... ok     (12 passed)
targets/SILENT .......................................... ok     (1 passed)
[...]
variables/MFILE_LIST .................................... ok     (1 passed)
variables/SHELL ......................................... Error running /tmp/make-3.81.91/__build__/tests/../make (expected 512; got 0): /tmp/make-3.81.91/__build__/tests/../make -f work/variables/SHELL.mk.6
FAILED (6/7 passed)
variables/automatic ..................................... ok     (7 passed)
variables/define ........................................ ok     (15 passed)

Are these a cause for concern?

I believe bsd_signal() is detected because the configure script checks whether the function links, not whether the headers provide a prototype.

The bsd_signal() check itself, as recorded in config.log, is pretty perfunctory:

configure:7340: checking for bsd_signal
configure:7340: cc -std -o conftest -g   conftest.c  >&5
configure:7340: $? = 0
configure:7340: result: yes

(I see that AC_CHECK_FUNCS() is used for this in configure.in, which does only check whether a function links.)

Anyway, looking at /usr/include/signal.h (attached), "#define _XOPEN_SOURCE_EXTENDED" is needed to get the bsd_signal() prototype. That allows main.c to compile.

But now I remember where the integer-type error came from. It's a knock-on effect of _X_S_E, causing trouble in the system's own header files:

source='../getloadavg.c' object='getloadavg.o' libtool=no  DEPDIR=.deps depmode=tru64 /usr/home/cport/tmp/bash ../config/depcomp  cc -std -DLOCALEDIR=\"/usr/local/share/locale\" -DLIBDIR=\"/usr/local/lib\" -DINCLUDEDIR=\"/usr/local/include\" -DHAVE_CONFIG_H -I. -I..  -I../glob   -D_XOPEN_SOURCE_EXTENDED  -g -c ../getloadavg.c
cc: Error: /usr/include/sys/mbuf.h, line 182: Missing type specifier or type qualifier. (missingtype)
        u_int        ext_size;                /* size of buffer, for ext_free */
--------^
cc: Error: /usr/include/sys/mbuf.h, line 417: Missing type specifier or type qualifier. (missingtype)
        u_long        m_mbufs;        /* obsolete: tracked by malloc M_MBUF stats */
--------^
cc: Error: /usr/include/sys/mbuf.h, line 418: Missing type specifier or type qualifier. (missingtype)
        u_long        m_clusters;        /* obsolete: tracked by malloc M_CLUSTER stats*/
--------^
cc: Error: /usr/include/sys/mbuf.h, line 419: Missing type specifier or type qualifier. (missingtype)
        u_long        m_drops;        /* times failed to find space */
--------^
cc: Error: /usr/include/sys/mbuf.h, line 420: Missing type specifier or type qualifier. (missingtype)
        u_long        m_drain;        /* times drained protocols for space */
--------^
cc: Error: /usr/include/sys/mbuf.h, line 421: Missing type specifier or type qualifier. (missingtype)
        u_int        m_mtypes[MT_MAX];        /* obsolete: tracked by MALLOC(type) stats */
--------^
[several more such errors elided]
cc: Severe: More than 30 errors were encountered in the course of compilation. (toomanyerr)
*** Exit 1
Stop.
*** Exit 1
Stop.
*** Exit 1
Stop.

As originally reported, adding "#define _OSF_SOURCE" does the trick.

(file #20969)

I'm attaching a copy of config.h, the bsd_signal() man page, and the preprocessed form of main.c. (I'm using the vendor's compiler, so it's just straight "cc -E", but hopefully that'll show what you need.) Relevant tidbits:

    #define HAVE_BSD_SIGNAL 1
    #define HAVE_SIGACTION 1

    void (*bsd_signal(int sig, void (*func)(int)))(int);

    typedef void (*__sigfp)(int);

(file #20949, file #20950, file #20951)

Okay, I pulled down make-3.81.90 and built on the Tru64 system without setting any flags. It looks like only one file is failing now, albeit with a similar error to what I saw before. Here's the output from a second pass of "make -i":

make  all-recursive
Making all in glob
Making all in config
No suffix list.
Making all in po
Making all in doc
source='../main.c' object='main.o' libtool=no  DEPDIR=.deps depmode=tru64 /usr/local/bin/bash ../config/depcomp  cc -std -DLOCALEDIR=\"/usr/local/share/locale\" -DLIBDIR=\"/usr/local/lib\" -DINCLUDEDIR=\"/usr/local/include\" -DHAVE_CONFIG_H -I. -I..  -I../glob     -g -c ../main.c
cc: Error: ../main.c, line 992: In this statement, "bsd_signal(...)" and "(__sigfp)1" cannot be compared for equality or inequality. (noequality)
  FATAL_SIG (SIGHUP);
--^
cc: Error: ../main.c, line 995: In this statement, "bsd_signal(...)" and "(__sigfp)1" cannot be compared for equality or inequality. (noequality)
  FATAL_SIG (SIGQUIT);
--^
cc: Error: ../main.c, line 997: In this statement, "bsd_signal(...)" and "(__sigfp)1" cannot be compared for equality or inequality. (noequality)
  FATAL_SIG (SIGINT);
--^
cc: Error: ../main.c, line 998: In this statement, "bsd_signal(...)" and "(__sigfp)1" cannot be compared for equality or inequality. (noequality)
  FATAL_SIG (SIGTERM);
--^
cc: Error: ../main.c, line 1011: In this statement, "bsd_signal(...)" and "(__sigfp)1" cannot be compared for equality or inequality. (noequality)
  FATAL_SIG (SIGXCPU);
--^
cc: Error: ../main.c, line 1014: In this statement, "bsd_signal(...)" and "(__sigfp)1" cannot be compared for equality or inequality. (noequality)
  FATAL_SIG (SIGXFSZ);
--^
* Exit 1 (ignored)
cc -std  -g   -o make ar.o arscan.o commands.o  default.o dir.o expand.o  file.o function.o getopt.o  getopt1.o implicit.o job.o  main.o misc.o read.o remake.o  remote-stub.o rule.o signame.o  strcache.o variable.o version.o  vpath.o hash.o getloadavg.o  glob/libglob.a    
ld:
Can't open: main.o (No such file or directory)
* Exit 1 (ignored)

config.guess returns "alphaev56-dec-osf4.0g".

I would add checks for the missing functions to the configure script, and if not have logic that automatically tries the feature test macros in case the functions aren't found, then at least a note alerting the user that these macros may address the problem.

Would it be helpful if I posted a log of errors encountered in building GNU Make without the macros?

Building GNU Make on Tru64 requires

    CPPFLAGS = -D_XOPEN_SOURCE_EXTENDED -D_OSF_SOURCE

_XOPEN* is needed to get the prototype for bsd_signal(), and _OSF* to typedef u_long and friends, which is used in some system headers pulled in by getloadavg.c (and without said typedefs, the build breaks when compiling that file). I've confirmed that neither of these flags is made redundant by the other.

Please make a note of this in the documentation, or add appropriate logic to the configure script. I was able to determine the need for these flags, but other users might not.