On 3/28/19 8:57 AM, Masahiro Yamada wrote:
Hi Joe,
OK, confirmed.
>
> [ ... snip .... ]
First, I was wondering why I could not reproduce this issue.
Then, I found the reason was I was using the latest GNU Make
compiled from the git source tree.
I found the following commit:
commit b90fabc8d6f34fb37d428dc0fb1b8b1951a9fbed
Author: Paul Smith <psmith@xxxxxxx>
Date: Sat May 27 20:07:30 2017 -0400
* NEWS: Do not insert a space during '+=' if the value is empty.
* doc/make.texi (Appending): Document this behavior.
* variable.c (do_variable_definition): Only add a space if the variable
value is not empty.
* tests/scripts/variables/flavors: Test this behavior.
diff --git a/NEWS b/NEWS
index e60644a..6e2c5c6 100644
--- a/NEWS
+++ b/NEWS
@@ -29,6 +29,12 @@
http://sv.gnu.org/bugs/index.php?group=make&report_id=111&fix_release_id=108&set
This was claimed to be fixed in 3.81, but wasn't, for some reason.
To detect this change search for 'nocomment' in the .FEATURES variable.
+* WARNING: Backward-incompatibility!
+ Previously appending using '+=' to an empty variable would result in a value
+ starting with a space. Now the initial space is only added if the variable
+ already contains some value. Similarly, appending an empty string does not
+ add a trailing space.
+
* The previous limit of 63 jobs under -jN on MS-Windows is now
increased to 4095. That limit includes the subprocess started by
the $(shell) function.
Applied to linux-kbuild/fixes with additional comments.
[Additional info by masahiro.yamada:
This issue only happens in the released versions of GNU Make.
CC_FLAGS_FTRACE will not contain the trailing space if you use
the latest GNU Make, which contains commit b90fabc8d6f3
("* NEWS: Do not insert a space during '+=' if the value is empty.")
]
Wow, this one gets even more specific. I had gone down the rabbit hole
on this one, I didn't care to learn how or why that extra space got
there :) Now we know, thanks for running that down and adding the note
about GNU Make.
-- Joe
