Fri Jan 29 22:52:29 2021 UTC ()

make(1): do not create empty shell files in jobs mode

In a chain of dependencies such as "all: build; build: do-build", the
intermediate targets do not have any commands.  In jobs mode,
nevertheless, an empty file was created and fed to the shell.  This was
unnecessary.  See jobs-empty-commands.mk.

The case of the special command line "...", which was suggested on
current-users, is not optimized since it doesn't occur in practice.

Suggested by Mateusz Guzik on current-users:
https://mail-index.netbsd.org/current-users/2021/01/26/msg040215.html


(rillig)

diff -r1.398 -r1.399 src/usr.bin/make/job.c

--- src/usr.bin/make/job.c 2021/01/19 20:51:46	1.398
+++ src/usr.bin/make/job.c 2021/01/29 22:52:29	1.399

 @@ -1,14 +1,14 @@
-/*	$NetBSD: job.c,v 1.398 2021/01/19 20:51:46 rillig Exp $	*/
+/*	$NetBSD: job.c,v 1.399 2021/01/29 22:52:29 rillig Exp $	*/
 /*
  * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
  * All rights reserved.
+ *
  * This code is derived from software contributed to Berkeley by
  * Adam de Boor.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
 @@ -133,27 +133,27 @@
 #ifndef USE_SELECT
 #include <poll.h>
 #endif
 #include <signal.h>
 #include <utime.h>
 #include "make.h"
 #include "dir.h"
 #include "job.h"
 #include "pathnames.h"
 #include "trace.h"
 /*	"@(#)job.c	8.2 (Berkeley) 3/19/94"	*/
-MAKE_RCSID("$NetBSD: job.c,v 1.398 2021/01/19 20:51:46 rillig Exp $");
+MAKE_RCSID("$NetBSD: job.c,v 1.399 2021/01/29 22:52:29 rillig Exp $");
 /*
  * A shell defines how the commands are run.  All commands for a target are
  * written into a single file, which is then given to the shell to execute
  * the commands from it.  The commands are written to the file using a few
  * templates for echo control and error control.
+ *
  * The name of the shell is the basename for the predefined shells, such as
  * "sh", "csh", "bash".  For custom shells, it is the full pathname, and its
  * basename is used to select the type of shell; the longest match wins.
  * So /usr/pkg/bin/bash has type sh, /usr/local/bin/tcsh has type csh.
+ *
  * The echoing of command lines is controlled using hasEchoCtl, echoOff,
 @@ -1656,28 +1656,33 @@ JobStart(GNode *gn, Boolean special)
 	/*
 	 * Check the commands now so any attributes from .DEFAULT have a
 	 * chance to migrate to the node.
 	 */
 	cmdsOK = Job_CheckCommands(gn, Error);
 	job->inPollfd = NULL;
 	/*
 	 * If the -n flag wasn't given, we open up OUR (not the child's)
 	 * temporary file to stuff commands in it. The thing is rd/wr so
 	 * we don't need to reopen it to feed it to the shell. If the -n
 	 * flag *was* given, we just set the file to be stdout. Cute, huh?
 	 */
-	if (((gn->type & OP_MAKE) && !opts.noRecursiveExecute) ||
+	if (Lst_IsEmpty(&gn->commands)) {
 		/* XXX: No need to flush stdout here */
 		job->cmdFILE = stdout;
 		run = FALSE;
 	} else if (((gn->type & OP_MAKE) && !opts.noRecursiveExecute) ||
 	    (!opts.noExecute && !opts.touchFlag)) {
 		/* XXX: The above conditions are needlessly repeated */
 		JobOpenTmpFile(job, gn, cmdsOK, &run);
 	} else if (!GNode_ShouldExecute(gn)) {
 		/*
 		 * Not executing anything -- just print all the commands to
 		 * stdout in one fell swoop. This will still set up
 		 * job->tailCmds correctly.
 		 */
 		SwitchOutputTo(gn);
 		job->cmdFILE = stdout;
 		/*
 		 * Only print the commands if they're ok, but don't die if
 		 * they're not -- just let the user know they're bad and
 		 * keep going. It doesn't do any harm in this case and may