bug#53358: 29.0.50; Compilation output messed up again

[Paul Eggert <eggert@cs.ucla.edu>]

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On 1/20/22 00:10, Lars Ingebrigtsen wrote:
> The problem is just in the ELC bit

Surely it's just an accident that you've seen it only for ELC, as the 
problem can occur if 'make' executes any two $(info ...)s at about the 
same time.

How badly does it occur for you? For me, it's only the first line (when 
many 'makes' start in parallel, which is a glitch I can easily ignore.

If it's a real annoyance please try the attached patch, which should fix 
the problem for the AM_V_ stuff at the cost of appending annoying empty 
lines with current and older GNU make. (Which annoyance do you prefer? 
:-) You'll need to run './config.status' after applying the patch.

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From 153f3d9af2b3d021d9ba8eb17d979c772a7c09cd Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Thu, 20 Jan 2022 10:11:39 -0800
Subject: [PATCH] Work around GNU Make $(info) bug

Problem reported by Lars Ingebrigtsen (Bug#53358).
* src/verbose.mk.in (newline, info-trailing-newline): New macros.
(AM_V_AR, AM_V_CC, AM_V_CXX, AM_V_CCLD, AM_V_CXXLD, AM_V_ELC)
(AM_V_ELN, AM_V_GEN, AM_V_RC): Use them.
---
 src/verbose.mk.in | 42 +++++++++++++++++++++++++++++++-----------
 1 file changed, 31 insertions(+), 11 deletions(-)

diff --git a/src/verbose.mk.in b/src/verbose.mk.in
index e3f5678303..4a3bbcb9de 100644
--- a/src/verbose.mk.in
+++ b/src/verbose.mk.in
@@ -17,6 +17,26 @@
 ## You should have received a copy of the GNU General Public License
 ## along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
 
+# Use two empty lines to define a macro containing a newline.
+define newline
+
+
+endef
+
+# Work around a bug in GNU Make 4.3 and earlier, which implements $(info MSG)
+# via two system calls { write (..., "MSG", 3); write (..., "\n", 1); }
+# which looks bad when make -j interleaves two of these at about the same time.
+# Later versions of GNU Make have the 'notintermediate' feature,
+# so assume that $(info ...) has the bug if this feature is absent.
+# The workaround arranges for 'MSG' itself to end in newline;
+# although this follows every message by an empty line,
+# that's better than the interleaved output.
+ifeq (,$(filter notintermediate,$(value .FEATURES)))
+info-trailing-newline = $(newline)
+else
+info-trailing-newline =
+endif
+
 # 'make' verbosity.
 V = @AM_DEFAULT_VERBOSITY@
 ifeq (${V},1)
@@ -33,26 +53,26 @@ AM_V_GLOBALS =
 AM_V_NO_PD =
 AM_V_RC =
 else
-AM_V_AR      = @$(info $   AR       $@)
+AM_V_AR      = @$(info $   AR       $@$(info-trailing-newline))
 AM_V_at = @
-AM_V_CC      = @$(info $   CC       $@)
-AM_V_CXX     = @$(info $   CXX      $@)
-AM_V_CCLD    = @$(info $   CCLD     $@)
-AM_V_CXXLD   = @$(info $   CXXLD    $@)
+AM_V_CC      = @$(info $   CC       $@$(info-trailing-newline))
+AM_V_CXX     = @$(info $   CXX      $@$(info-trailing-newline))
+AM_V_CCLD    = @$(info $   CCLD     $@$(info-trailing-newline))
+AM_V_CXXLD   = @$(info $   CXXLD    $@$(info-trailing-newline))
 ifeq ($(HAVE_NATIVE_COMP),yes)
 ifeq ($(NATIVE_DISABLED),1)
-AM_V_ELC     = @$(info $   ELC      $@)
+AM_V_ELC     = @$(info $   ELC      $@$(info-trailing-newline))
 AM_V_ELN =
 else
-AM_V_ELC     = @$(info $   ELC+ELN  $@)
-AM_V_ELN     = @$(info $   ELN      $@)
+AM_V_ELC     = @$(info $   ELC+ELN  $@$(info-trailing-newline))
+AM_V_ELN     = @$(info $   ELN      $@$(info-trailing-newline))
 endif
 else
-AM_V_ELC     = @$(info $   ELC      $@)
+AM_V_ELC     = @$(info $   ELC      $@$(info-trailing-newline))
 AM_V_ELN =
 endif
-AM_V_GEN     = @$(info $   GEN      $@)
+AM_V_GEN     = @$(info $   GEN      $@$(info-trailing-newline))
 AM_V_GLOBALS = @$(info $   GEN      globals.h)
 AM_V_NO_PD = --no-print-directory
-AM_V_RC      = @$(info $   RC       $@)
+AM_V_RC      = @$(info $   RC       $@$(info-trailing-newline))
 endif
-- 
2.32.0