[bug #46596] Timestamp check behaviour difference in clean build and rebuild on rules without recipes

[Stefan Becker]

URL:
  <http://savannah.gnu.org/bugs/?46596>

                 Summary: Timestamp check behaviour difference in clean build
and rebuild on rules without recipes
                 Project: make
            Submitted by: stefanb
            Submitted on: Thu 03 Dec 2015 07:58:39 AM GMT
                Severity: 3 - Normal
              Item Group: Bug
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
       Component Version: 4.1
        Operating System: None
           Fixed Release: None
           Triage Status: None

    _______________________________________________________

Details:

We encountered a difference how timestamps are handled between clean builds
and rebuild depending if a rule has a recipe or not. If a rule doesn't have a
recipe GNU make doesn't check the timestamp of the dependency correctly and
therefore fails to trigger recipes from dependent rules.

I have checked GNU make 3.81, 4.0 and 4.1: they are all affected by this
issue.

I've attached 3 makefiles that highlight the problem. We have

* file "a" that depends on file "b"
* file "b" is one of the files generated when file "d" is updated
* the target for dependency "d" is file/.PHONY target "c"
* the empty rule "b: c" makes sure that the dependencies are correct, i.e.
when we ask for "a" the rule for "c" is triggered

Without recipe attached to rule "b: c" the file "a" is not updated on first
rebuild, only on the second one.

Example 1 uses a .PHONY target for "c", example 2 does not. The example output
is generated with make 4.1 to have the "--trace" option available.


Example 1: wrong execution on rebuild:


$ make --version
GNU Make 4.1
Built for x86_64-unknown-linux-gnu
...

# clean build
$ make clean
rm -f a b c d e
$ make --no-print-directory --trace
Makefile:21: target 'c' does not exist
make -f Makefile2
Makefile2:8: target 'd' does not exist
touch d
Makefile2:5: update target 'b' due to: d
cp d b
Makefile:7: update target 'a' due to: b
cp b a

# rebuild without source change
$ make --no-print-directory --trace
Makefile:21: target 'c' does not exist
make -f Makefile2
make[1]: Nothing to be done for 'all'.

# 1st rebuild after source change
$ touch d
$ make --no-print-directory --trace
Makefile:21: target 'c' does not exist
make -f Makefile2
Makefile2:5: update target 'b' due to: d
cp d b

# 2nd rebuild after source change
$ make --no-print-directory --trace
Makefile:21: target 'c' does not exist
make -f Makefile2
make[1]: Nothing to be done for 'all'.
Makefile:7: update target 'a' due to: b
cp b a

# 3rd rebuild after source change
$ make --no-print-directory --trace
Makefile:21: target 'c' does not exist
make -f Makefile2
make[1]: Nothing to be done for 'all'.

# check that other target doesn't trigger phony target
$ make --no-print-directory --trace all2
Makefile:24: target 'e' does not exist
touch e


Example 1: correct execution on rebuild by adding a no-op ":" recipe


# clean build
$ make clean
rm -f a b c d e
$ make --no-print-directory --trace _workaround1:=1
Makefile:21: target 'c' does not exist
make -f Makefile2
Makefile2:8: target 'd' does not exist
touch d
Makefile2:5: update target 'b' due to: d
cp d b
Makefile:14: update target 'b' due to: c
:
Makefile:7: update target 'a' due to: b
cp b a

# rebuild without source change
$ make --no-print-directory --trace _workaround1:=1
Makefile:21: target 'c' does not exist
make -f Makefile2
make[1]: Nothing to be done for 'all'.
Makefile:14: update target 'b' due to: c
:

# 1st rebuild after source change
$ touch d
$ make --no-print-directory --trace _workaround1:=1
Makefile:21: target 'c' does not exist
make -f Makefile2
Makefile2:5: update target 'b' due to: d
cp d b
Makefile:14: update target 'b' due to: c
:
Makefile:7: update target 'a' due to: b
cp b a

# 2nd rebuild after source change
$ make --no-print-directory --trace _workaround1:=1
Makefile:21: target 'c' does not exist
make -f Makefile2
make[1]: Nothing to be done for 'all'.
Makefile:14: update target 'b' due to: c
:


Example 1: correct execution on rebuild by adding an empty recipe


# clean build
$ make clean
rm -f a b c d e
$ make --no-print-directory --trace _workaround2:=1
Makefile:21: target 'c' does not exist
make -f Makefile2
Makefile2:8: target 'd' does not exist
touch d
Makefile2:5: update target 'b' due to: d
cp d b
Makefile:7: update target 'a' due to: b
cp b a

# rebuild without source change
$ make --no-print-directory --trace _workaround2:=1
Makefile:21: target 'c' does not exist
make -f Makefile2
make[1]: Nothing to be done for 'all'.

# 1st rebuild after source change
$ touch d
$ make --no-print-directory --trace _workaround2:=1
Makefile:21: target 'c' does not exist
make -f Makefile2
Makefile2:5: update target 'b' due to: d
cp d b
Makefile:7: update target 'a' due to: b
cp b a

# 2nd rebuild after source change
$ make --no-print-directory --trace _workaround2:=1
Makefile:21: target 'c' does not exist
make -f Makefile2
make[1]: Nothing to be done for 'all'.



Example 2: wrong execution on rebuild:


# clean build
$ make -f Makefile.no-phony clean
rm -f a b c d e

# rebuild without source change
$ make -f Makefile.no-phony --trace
Makefile.no-phony:23: target 'd' does not exist
touch d
Makefile.no-phony:19: update target 'c' due to: d
touch c
touch b
Makefile.no-phony:7: update target 'a' due to: b
cp b a

# 1st rebuild after source change
$ touch d
$ make -f Makefile.no-phony --trace
Makefile.no-phony:19: update target 'c' due to: d
touch c
touch b

# 2nd rebuild after source change
$ make -f Makefile.no-phony --trace
Makefile.no-phony:7: update target 'a' due to: b
cp b a

# 3rd rebuild after source change
$ make -f Makefile.no-phony --trace
make: Nothing to be done for 'all'.


Example 2: correct execution on rebuild by adding a no-op ":" recipe


# clean build
$ make -f Makefile.no-phony clean
rm -f a b c d e
$ make -f Makefile.no-phony --trace _workaround1:=1
Makefile.no-phony:23: target 'd' does not exist
touch d
Makefile.no-phony:19: update target 'c' due to: d
touch c
touch b
Makefile.no-phony:14: update target 'b' due to: c
:
Makefile.no-phony:7: update target 'a' due to: b
cp b a

# rebuild without source change
$ make -f Makefile.no-phony --trace _workaround1:=1
make: Nothing to be done for 'all'.

# 1st rebuild after source change
$ touch d
$ make -f Makefile.no-phony --trace _workaround1:=1
Makefile.no-phony:19: update target 'c' due to: d
touch c
touch b
Makefile.no-phony:14: update target 'b' due to: c
:
Makefile.no-phony:7: update target 'a' due to: b
cp b a

# 2nd rebuild after source change
$ make -f Makefile.no-phony --trace _workaround1:=1
make: Nothing to be done for 'all'.


Example 2: correct execution on rebuild by adding an empty recipe


# clean build
$ make -f Makefile.no-phony clean
rm -f a b c d e
$ make -f Makefile.no-phony --trace _workaround2:=1
Makefile.no-phony:23: target 'd' does not exist
touch d
Makefile.no-phony:19: update target 'c' due to: d
touch c
touch b
Makefile.no-phony:7: update target 'a' due to: b
cp b a

# rebuild without source change
$ make -f Makefile.no-phony --trace _workaround2:=1
make: Nothing to be done for 'all'.

# 1st rebuild after source change
$ touch d
$ make -f Makefile.no-phony --trace _workaround2:=1
Makefile.no-phony:19: update target 'c' due to: d
touch c
touch b
Makefile.no-phony:7: update target 'a' due to: b
cp b a

# 2nd rebuild after source change
$ make -f Makefile.no-phony --trace _workaround2:=1
make: Nothing to be done for 'all'.





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File Attachments:


-------------------------------------------------------
Date: Thu 03 Dec 2015 07:58:39 AM GMT  Name: Makefile  Size: 233B   By:
stefanb
Example makefiles
<http://savannah.gnu.org/bugs/download.php?file_id=35624>
-------------------------------------------------------
Date: Thu 03 Dec 2015 07:58:39 AM GMT  Name: Makefile2  Size: 48B   By:
stefanb
Example makefiles
<http://savannah.gnu.org/bugs/download.php?file_id=35625>
-------------------------------------------------------
Date: Thu 03 Dec 2015 07:58:39 AM GMT  Name: Makefile.no-phony  Size: 185B  
By: stefanb
Example makefiles
<http://savannah.gnu.org/bugs/download.php?file_id=35626>

    _______________________________________________________

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