Re: SCons misses a dependency which results in incorrect output.

Tal Dayan <[email protected]> Wed, 16 Jul 2025 17:14:40 -0700
Newsgroups gmane.comp.programming.tools.scons.user
Message-ID <CAM+zu_4-KWDR3O7K4ZN2Uv=vdir-vvu_vgBGhkrsKWaF6ADSbw@mail.gmail.com>
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Our system is based on Python plugin classes that provide scons Builders so
I wonder if we can just define our own subclass of Builder that
automatically adds the deletion on errors functionality.

https://github.com/FPGAwars/apio/blob/008b090e92246414353776ef5df4c0dd3e274=
fab/apio/scons/plugin_ice40.py#L62C16-L62C23

On Wed, Jul 16, 2025 at 5:02=E2=80=AFPM Bill Deegan <bill@baddogconsulting.=
com>
wrote:

> Tai,
>
> If you have a program you're running as the action in a command which is
> erroring out but writing the file, you can work around this issue for the
> time being by wrapping that program with a script which checks the exit
> value of your program, and removing the target files if it exits with an
> error status.
>
> That should be sufficient to get you going again.
>
> -Bill
>
> On Wed, Jul 16, 2025 at 3:18=E2=80=AFPM Bill Deegan <bill@baddogconsultin=
g.com>
> wrote:
>
>> Did you read my explanation and how to fix it in your environment
>> assuming command.sh is similar to what's really happening in your build?
>>
>>
>> On Wed, Jul 16, 2025 at 3:16=E2=80=AFPM Bill Deegan <bill@baddogconsulti=
ng.com>
>> wrote:
>>
>>> It's an enhancement request.
>>>
>>> The bug is in your command.sh script.
>>> I'll change the description and text.
>>>
>>>
>>>
>>> On Wed, Jul 16, 2025 at 12:56=E2=80=AFPM Tal Dayan <[email protected]> wrot=
e:
>>>
>>>> Hi Bill, I will file an issue.
>>>>
>>>> I don't think it's safe for SCons to assume that once a program writes
>>>> an output file it can't crash.
>>>>
>>>> On Wed, Jul 16, 2025 at 12:45=E2=80=AFPM Bill Deegan <bill@baddogconsu=
lting.com>
>>>> wrote:
>>>>
>>>>> Arguably your command.sh is incorrectly written.
>>>>>
>>>>>  It copies the file and then checks it's contents and exits with erro=
r
>>>>> status if there improper.
>>>>>
>>>>> So a quick fix would be to check the input before copying the file.
>>>>>
>>>>> From the URL you posted in other email here's the command.sh
>>>>> #!/bin/bash
>>>>> # Usage: ./command input > output
>>>>>
>>>>> # Copy source to destination
>>>>> cp "$1" "$2"
>>>>>
>>>>> # If the input file stats with 'bad' inject an error AFTER creating
>>>>> the output file.
>>>>>
>>>>> first_line=3D$(head -n 1 "$1")
>>>>>
>>>>> if [[ "$first_line" =3D=3D bad* ]]; then
>>>>>   exit 1
>>>>> fi
>>>>>
>>>>> exit 0
>>>>>
>>>>> Change it to this:
>>>>> #!/bin/bash
>>>>> # Usage: ./command input > output
>>>>>
>>>>> # If the input file stats with 'bad' inject an error AFTER creating
>>>>> the output file.
>>>>>
>>>>> first_line=3D$(head -n 1 "$1")
>>>>>
>>>>> if [[ "$first_line" =3D=3D bad* ]]; then
>>>>>   exit 1
>>>>> fi
>>>>>
>>>>> # Copy source to destination
>>>>> cp "$1" "$2"
>>>>>
>>>>> exit 0
>>>>>
>>>>> Results:
>>>>>
>>>>> % ./run.sh
>>>>>
>>>>> ----- Iteration 1: file1 =3D 'good' -----
>>>>>
>>>>> scons: Reading SConscript files ...
>>>>> scons: done reading SConscript files.
>>>>> scons: Building targets ...
>>>>> scons: building `file2' because it doesn't exist
>>>>> ./command.sh file1 file2
>>>>> +-file2
>>>>>   +-file1
>>>>> scons: done building targets.
>>>>>
>>>>> File1
>>>>> MD5 (file1) =3D d7f986677d9f563bd1794b09d82206a3
>>>>>      1 good
>>>>>
>>>>> File2
>>>>> MD5 (file2) =3D d7f986677d9f563bd1794b09d82206a3
>>>>>      1 good
>>>>>
>>>>> DBlite:
>>>>> =3D=3D=3D .:
>>>>> file1: d7f986677d9f563bd1794b09d82206a3 1752694898 5
>>>>> file2: d7f986677d9f563bd1794b09d82206a3 1752694898 5
>>>>>         file1: d7f986677d9f563bd1794b09d82206a3 1752694898 5
>>>>>         2dbc2dce125a753309a27b7d5157aaaa [./command.sh $SOURCE $TARGE=
T]
>>>>>
>>>>> ----- Iteration 2: file1 =3D 'bad' -----
>>>>>
>>>>> scons: Reading SConscript files ...
>>>>> scons: done reading SConscript files.
>>>>> scons: Building targets ...
>>>>> scons: rebuilding `file2' because `file1' changed
>>>>> ./command.sh file1 file2
>>>>> scons: *** [file2] Error 1
>>>>> +-file2
>>>>>   +-file1
>>>>> scons: building terminated because of errors.
>>>>>
>>>>> File1
>>>>> MD5 (file1) =3D df207dc9143c6fabf60b69b9c3035103
>>>>>      1 bad
>>>>>
>>>>> File2
>>>>> md5: file2: No such file or directory
>>>>> cat: file2: No such file or directory
>>>>>
>>>>> DBlite:
>>>>> =3D=3D=3D .:
>>>>> file1: df207dc9143c6fabf60b69b9c3035103 1752694898 4
>>>>> file2: d7f986677d9f563bd1794b09d82206a3 1752694898 5
>>>>>         file1: d7f986677d9f563bd1794b09d82206a3 1752694898 5
>>>>>         2dbc2dce125a753309a27b7d5157aaaa [./command.sh $SOURCE $TARGE=
T]
>>>>>
>>>>> ----- Iteration 3: file1 =3D 'good' -----
>>>>>
>>>>> scons: Reading SConscript files ...
>>>>> scons: done reading SConscript files.
>>>>> scons: Building targets ...
>>>>> scons: building `file2' because it doesn't exist
>>>>> ./command.sh file1 file2
>>>>> +-file2
>>>>>   +-file1
>>>>> scons: done building targets.
>>>>>
>>>>> File1
>>>>> MD5 (file1) =3D d7f986677d9f563bd1794b09d82206a3
>>>>>      1 good
>>>>>
>>>>> File2
>>>>> MD5 (file2) =3D d7f986677d9f563bd1794b09d82206a3
>>>>>      1 good
>>>>>
>>>>> DBlite:
>>>>> =3D=3D=3D .:
>>>>> file1: d7f986677d9f563bd1794b09d82206a3 1752694899 5
>>>>> file2: d7f986677d9f563bd1794b09d82206a3 1752694899 5
>>>>>         file1: d7f986677d9f563bd1794b09d82206a3 1752694899 5
>>>>>         2dbc2dce125a753309a27b7d5157aaaa [./command.sh $SOURCE $TARGE=
T]
>>>>>
>>>>> There's not presently logic in SCons to delete target files if the
>>>>> associated action yields an error.
>>>>>
>>>>> I think what you want is equivalent to makes .DELETE_ON_FAILURE,
>>>>> there's actually a SO question on this:
>>>>>
>>>>> https://stackoverflow.com/questions/29546276/scons-delete-target-on-f=
ailure-of-any-action
>>>>>
>>>>> Please go ahead and file an enhancement request to add equivalent
>>>>> to DELETE_ON_FAILURE, please include your reproducer scripts.
>>>>>
>>>>> -Bill
>>>>>
>>>>> On Wed, Jul 16, 2025 at 10:44=E2=80=AFAM Tal Dayan <[email protected]> wr=
ote:
>>>>>
>>>>>> Looking at the end state of scons after invocation #3, the actual md=
5
>>>>>> of file2 doesn't match its md5 in the dblite.
>>>>>>
>>>>>> https://i.imgur.com/NGco3yQ.png
>>>>>>
>>>>>> On Wed, Jul 16, 2025 at 10:33=E2=80=AFAM Tal Dayan <[email protected]> w=
rote:
>>>>>>
>>>>>>> Hi Keith, I updated the example files here
>>>>>>> https://github.com/FPGAwars/apio/issues/676
>>>>>>>
>>>>>>> They now include the md5 of the files and a dump of .sconsign.dblit=
e
>>>>>>>
>>>>>>> On Wed, Jul 16, 2025 at 10:08=E2=80=AFAM Keith Prussing <
>>>>>>> [email protected]> wrote:
>>>>>>>
>>>>>>>> I suspect it's because `file1` has the same hash in the
>>>>>>>> .sconsign.dblite as the last "good" build (i.e. the first one). Th=
us
>>>>>>>> you get the line "scons: `file2' is up to date." on the third run.
>>>>>>>> However, I am not an expert in the specifics of SCons' hashing
>>>>>>>> methods.
>>>>>>>>
>>>>>>>> On Wed, Jul 16, 2025 at 12:38=E2=80=AFPM Tal Dayan <[email protected]>=
 wrote:
>>>>>>>> >
>>>>>>>> > Hi all,
>>>>>>>> >
>>>>>>>> > We encountered this problem with the nextpnr tool and created
>>>>>>>> here a small and independent example that demonstrates it.
>>>>>>>> >
>>>>>>>> > In the example below, a shell script 'command.sh' reads the
>>>>>>>> source file 'file1' and writes it to the target file 'file2'. Howe=
ver, if
>>>>>>>> the
>>>>>>>> > source file starts with 'bad' it exits with an error code,
>>>>>>>> *after* creating the target file.
>>>>>>>> >
>>>>>>>> > The script `run.sh', runs scons three times with these values of
>>>>>>>> the source file file1 'good', 'bad', and 'good'.  The expectation =
is that
>>>>>>>> after the third scons run, file2 should contain the value 'good' b=
ut it
>>>>>>>> contains the value 'bad'.
>>>>>>>> >
>>>>>>>> > Do we miss anything or is it simply a bug?
>>>>>>>> >
>>>>>>>> > SConstruct:
>>>>>>>> >
>>>>>>>> > ----------------------------------------------
>>>>>>>> >
>>>>>>>> > # SCons environment
>>>>>>>> >
>>>>>>>> > env =3D Environment()
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > # Copy file1 =E2=86=92 file2 using command.sh
>>>>>>>> >
>>>>>>>> > # Inject an error if file1 starts with 'bad"
>>>>>>>> >
>>>>>>>> > file2 =3D env.Command(
>>>>>>>> >
>>>>>>>> >     target=3D'file2',
>>>>>>>> >
>>>>>>>> >     source=3D'file1',
>>>>>>>> >
>>>>>>>> >     action=3D'./command.sh $SOURCE > $TARGET'
>>>>>>>> >
>>>>>>>> > )
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > # Make 'file2' the default target
>>>>>>>> >
>>>>>>>> > Default(file2)
>>>>>>>> >
>>>>>>>> > ----------------------------------------------
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > command.sh:
>>>>>>>> >
>>>>>>>> > ----------------------------------------------
>>>>>>>> >
>>>>>>>> > #!/bin/bash
>>>>>>>> >
>>>>>>>> > # Usage: ./command input > output
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > # Read from the first argument and copy to stdout
>>>>>>>> >
>>>>>>>> > cat "$1"
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > # If the input file starts with 'bad', inject an error AFTER
>>>>>>>> creating the output file.
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > first_line=3D$(head -n 1 "$1")
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > if [[ "$first_line" =3D=3D bad* ]]; then
>>>>>>>> >
>>>>>>>> >   exit 1
>>>>>>>> >
>>>>>>>> > fi
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > exit 0
>>>>>>>> >
>>>>>>>> > ----------------------------------------------
>>>>>>>> >
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > run.sh
>>>>>>>> >
>>>>>>>> > ----------------------------------------------
>>>>>>>> >
>>>>>>>> > #!/bin/bash
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > # Clean up.
>>>>>>>> >
>>>>>>>> > rm -f .sconsign.dblite
>>>>>>>> >
>>>>>>>> > rm -f file[12]
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > echo
>>>>>>>> >
>>>>>>>> > echo "---- Iteration 1: file1 =3D 'good'"
>>>>>>>> >
>>>>>>>> > echo "good" > file1
>>>>>>>> >
>>>>>>>> > scons
>>>>>>>> >
>>>>>>>> > echo
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > echo "File1"
>>>>>>>> >
>>>>>>>> > cat -n file1
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > echo "File2"
>>>>>>>> >
>>>>>>>> > cat -n file2
>>>>>>>> >
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > echo
>>>>>>>> >
>>>>>>>> > echo "---- Iteration 2: file1 =3D 'bad'"
>>>>>>>> >
>>>>>>>> > echo "bad" > file1
>>>>>>>> >
>>>>>>>> > cat -n file1
>>>>>>>> >
>>>>>>>> > scons
>>>>>>>> >
>>>>>>>> > echo
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > echo "File1"
>>>>>>>> >
>>>>>>>> > cat -n file1
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > echo "File2"
>>>>>>>> >
>>>>>>>> > cat -n file2
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > echo
>>>>>>>> >
>>>>>>>> > echo "---- Iteration 3: file1 =3D 'good'"
>>>>>>>> >
>>>>>>>> > echo "good" > file1
>>>>>>>> >
>>>>>>>> > cat -n file1
>>>>>>>> >
>>>>>>>> > scons
>>>>>>>> >
>>>>>>>> > echo
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > echo "File1"
>>>>>>>> >
>>>>>>>> > cat -n file1
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > echo "File2"
>>>>>>>> >
>>>>>>>> > cat -n file2
>>>>>>>> >
>>>>>>>> > ----------------------------------------------
>>>>>>>> >
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > Run log:
>>>>>>>> >
>>>>>>>> > ----------------------------------------------
>>>>>>>> >
>>>>>>>> > $ ./run.sh
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > ---- Iteration 1: file1 =3D 'good'
>>>>>>>> >
>>>>>>>> > scons: Reading SConscript files ...
>>>>>>>> >
>>>>>>>> > scons: done reading SConscript files.
>>>>>>>> >
>>>>>>>> > scons: Building targets ...
>>>>>>>> >
>>>>>>>> > ./command.sh file1 > file2
>>>>>>>> >
>>>>>>>> > scons: done building targets.
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > File1
>>>>>>>> >
>>>>>>>> >      1 good
>>>>>>>> >
>>>>>>>> > File2
>>>>>>>> >
>>>>>>>> >      1 good
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > ---- Iteration 2: file1 =3D 'bad'
>>>>>>>> >
>>>>>>>> >      1 bad
>>>>>>>> >
>>>>>>>> > scons: Reading SConscript files ...
>>>>>>>> >
>>>>>>>> > scons: done reading SConscript files.
>>>>>>>> >
>>>>>>>> > scons: Building targets ...
>>>>>>>> >
>>>>>>>> > ./command.sh file1 > file2
>>>>>>>> >
>>>>>>>> > scons: *** [file2] Error 1
>>>>>>>> >
>>>>>>>> > scons: building terminated because of errors.
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > File1
>>>>>>>> >
>>>>>>>> >      1 bad
>>>>>>>> >
>>>>>>>> > File2
>>>>>>>> >
>>>>>>>> >      1 bad
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > ---- Iteration 1: file1 =3D 'good'
>>>>>>>> >
>>>>>>>> >      1 good
>>>>>>>> >
>>>>>>>> > scons: Reading SConscript files ...
>>>>>>>> >
>>>>>>>> > scons: done reading SConscript files.
>>>>>>>> >
>>>>>>>> > scons: Building targets ...
>>>>>>>> >
>>>>>>>> > scons: `file2' is up to date.
>>>>>>>> >
>>>>>>>> > scons: done building targets.
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > File1
>>>>>>>> >
>>>>>>>> >      1 good
>>>>>>>> >
>>>>>>>> > File2
>>>>>>>> >
>>>>>>>> >      1 bad
>>>>>>>> >
>>>>>>>> > ----------------------------------------------
>>>>>>>> >
>>>>>>>> > _______________________________________________
>>>>>>>> > Scons-users mailing list
>>>>>>>> > [email protected]
>>>>>>>> > https://pairlist4.pair.net/mailman/listinfo/scons-users
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> Keith Prussing
>>>>>>>> _______________________________________________
>>>>>>>> Scons-users mailing list
>>>>>>>> [email protected]
>>>>>>>> https://pairlist4.pair.net/mailman/listinfo/scons-users
>>>>>>>>
>>>>>>> _______________________________________________
>>>>>> Scons-users mailing list
>>>>>> [email protected]
>>>>>> https://pairlist4.pair.net/mailman/listinfo/scons-users
>>>>>>
>>>>> _______________________________________________
>>>>> Scons-users mailing list
>>>>> [email protected]
>>>>> https://pairlist4.pair.net/mailman/listinfo/scons-users
>>>>>
>>>> _______________________________________________
>>>> Scons-users mailing list
>>>> [email protected]
>>>> https://pairlist4.pair.net/mailman/listinfo/scons-users
>>>>
>>> _______________________________________________
> Scons-users mailing list
> [email protected]
> https://pairlist4.pair.net/mailman/listinfo/scons-users
>

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<div dir=3D"ltr">Our system is based on Python plugin classes that provide =
scons Builders so I wonder if we can just define our own subclass of Builde=
r that automatically adds=C2=A0the=C2=A0deletion on errors functionality.<d=
iv><br></div><div><a href=3D"https://github.com/FPGAwars/apio/blob/008b090e=
92246414353776ef5df4c0dd3e274fab/apio/scons/plugin_ice40.py#L62C16-L62C23">=
https://github.com/FPGAwars/apio/blob/008b090e92246414353776ef5df4c0dd3e274=
fab/apio/scons/plugin_ice40.py#L62C16-L62C23</a></div></div><br><div class=
=3D"gmail_quote gmail_quote_container"><div dir=3D"ltr" class=3D"gmail_attr=
">On Wed, Jul 16, 2025 at 5:02=E2=80=AFPM Bill Deegan &lt;<a href=3D"mailto=
:[email protected]">[email protected]</a>&gt; wrote:<br></d=
iv><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;bord=
er-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr"><div>=
Tai,</div><div><br></div><div>If you have a program you&#39;re running as t=
he action in a command which is erroring out but writing the file, you can =
work around this issue for the time being by wrapping that program with a s=
cript which checks the exit value of your program, and removing the target =
files if it exits with an error status.</div><div><br></div><div>That shoul=
d be sufficient to get you going again.</div><div><br></div><div>-Bill</div=
></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr"=
>On Wed, Jul 16, 2025 at 3:18=E2=80=AFPM Bill Deegan &lt;<a href=3D"mailto:=
[email protected]" target=3D"_blank">[email protected]</a>&=
gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0=
px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div =
dir=3D"ltr"><div>Did you read my explanation and how to fix it in your envi=
ronment assuming command.sh is similar to what&#39;s really happening in yo=
ur build?</div><div><br></div></div><br><div class=3D"gmail_quote"><div dir=
=3D"ltr" class=3D"gmail_attr">On Wed, Jul 16, 2025 at 3:16=E2=80=AFPM Bill =
Deegan &lt;<a href=3D"mailto:[email protected]" target=3D"_blank">b=
[email protected]</a>&gt; wrote:<br></div><blockquote class=3D"gmail=
_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204=
,204);padding-left:1ex"><div dir=3D"ltr"><div>It&#39;s an enhancement reque=
st.</div><div><br></div><div>The bug is in your=C2=A0command.sh script.</di=
v><div>I&#39;ll change the description and text.</div><div><br></div><div><=
br></div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gma=
il_attr">On Wed, Jul 16, 2025 at 12:56=E2=80=AFPM Tal Dayan &lt;<a href=3D"=
mailto:[email protected]" target=3D"_blank">[email protected]</a>&gt; wrote:<br></d=
iv><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;bord=
er-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr">Hi Bi=
ll, I will file an issue.<div><br></div><div>I don&#39;t think it&#39;s saf=
e for SCons to assume that once a program writes an output file it can&#39;=
t crash.=C2=A0</div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" c=
lass=3D"gmail_attr">On Wed, Jul 16, 2025 at 12:45=E2=80=AFPM Bill Deegan &l=
t;<a href=3D"mailto:[email protected]" target=3D"_blank">bill@baddo=
gconsulting.com</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" s=
tyle=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);pad=
ding-left:1ex"><div dir=3D"ltr"><div>Arguably your command.sh is incorrectl=
y written.</div><div><br></div><div>=C2=A0It copies the file and then check=
s it&#39;s contents and exits with error status if there improper.</div><di=
v><br></div><div>So a quick fix would be to check the input before copying =
the file.</div><div><br></div><div>From the URL you posted in other email h=
ere&#39;s the command.sh</div><div><span style=3D"font-family:monospace">#!=
/bin/bash<br># Usage: ./command input &gt; output<br><br># Copy source to d=
estination<br>cp &quot;$1&quot; &quot;$2&quot;<br><br># If the input file s=
tats with &#39;bad&#39; inject an error AFTER creating the output file.<br>=
<br>first_line=3D$(head -n 1 &quot;$1&quot;)<br><br>if [[ &quot;$first_line=
&quot; =3D=3D bad* ]]; then<br>=C2=A0 exit 1<br>fi<br><br>exit 0</span></di=
v><div><span style=3D"font-family:monospace"><br></span></div><div><span st=
yle=3D"font-family:monospace">Change it to this:</span></div><div><span sty=
le=3D"font-family:monospace">#!/bin/bash<br># Usage: ./command input &gt; o=
utput<br><br># If the input file stats with &#39;bad&#39; inject an error A=
FTER creating the output file.<br><br>first_line=3D$(head -n 1 &quot;$1&quo=
t;)<br><br>if [[ &quot;$first_line&quot; =3D=3D bad* ]]; then<br>=C2=A0 exi=
t 1<br>fi<br><br># Copy source to destination<br>cp &quot;$1&quot; &quot;$2=
&quot;<br><br>exit 0</span><br><br></div><div>Results:</div><div><br></div>=
<div><span style=3D"font-family:monospace">% ./run.sh<br><br>----- Iteratio=
n 1: file1 =3D &#39;good&#39; -----<br><br>scons: Reading SConscript files =
...<br>scons: done reading SConscript files.<br>scons: Building targets ...=
<br>scons: building `file2&#39; because it doesn&#39;t exist<br>./command.s=
h file1 file2<br>+-file2<br>=C2=A0 +-file1<br>scons: done building targets.=
<br><br>File1<br>MD5 (file1) =3D d7f986677d9f563bd1794b09d82206a3<br>=C2=A0=
 =C2=A0 =C2=A01	good<br><br>File2<br>MD5 (file2) =3D d7f986677d9f563bd1794b=
09d82206a3<br>=C2=A0 =C2=A0 =C2=A01	good<br><br>DBlite:<br>=3D=3D=3D .:<br>=
file1: d7f986677d9f563bd1794b09d82206a3 1752694898 5<br>file2: d7f986677d9f=
563bd1794b09d82206a3 1752694898 5<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 file1: d7f=
986677d9f563bd1794b09d82206a3 1752694898 5<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 2=
dbc2dce125a753309a27b7d5157aaaa [./command.sh $SOURCE $TARGET]<br><br>-----=
 Iteration 2: file1 =3D &#39;bad&#39; -----<br><br>scons: Reading SConscrip=
t files ...<br>scons: done reading SConscript files.<br>scons: Building tar=
gets ...<br>scons: rebuilding `file2&#39; because `file1&#39; changed<br>./=
command.sh file1 file2<br>scons: *** [file2] Error 1<br>+-file2<br>=C2=A0 +=
-file1<br>scons: building terminated because of errors.<br><br>File1<br>MD5=
 (file1) =3D df207dc9143c6fabf60b69b9c3035103<br>=C2=A0 =C2=A0 =C2=A01	bad<=
br><br>File2<br>md5: file2: No such file or directory<br>cat: file2: No suc=
h file or directory<br><br>DBlite:<br>=3D=3D=3D .:<br>file1: df207dc9143c6f=
abf60b69b9c3035103 1752694898 4<br>file2: d7f986677d9f563bd1794b09d82206a3 =
1752694898 5<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 file1: d7f986677d9f563bd1794b09=
d82206a3 1752694898 5<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 2dbc2dce125a753309a27b=
7d5157aaaa [./command.sh $SOURCE $TARGET]<br><br>----- Iteration 3: file1 =
=3D &#39;good&#39; -----<br><br>scons: Reading SConscript files ...<br>scon=
s: done reading SConscript files.<br>scons: Building targets ...<br>scons: =
building `file2&#39; because it doesn&#39;t exist<br>./command.sh file1 fil=
e2<br>+-file2<br>=C2=A0 +-file1<br>scons: done building targets.<br><br>Fil=
e1<br>MD5 (file1) =3D d7f986677d9f563bd1794b09d82206a3<br>=C2=A0 =C2=A0 =C2=
=A01	good<br><br>File2<br>MD5 (file2) =3D d7f986677d9f563bd1794b09d82206a3<=
br>=C2=A0 =C2=A0 =C2=A01	good<br><br>DBlite:<br>=3D=3D=3D .:<br>file1: d7f9=
86677d9f563bd1794b09d82206a3 1752694899 5<br>file2: d7f986677d9f563bd1794b0=
9d82206a3 1752694899 5<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 file1: d7f986677d9f56=
3bd1794b09d82206a3 1752694899 5<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 2dbc2dce125a=
753309a27b7d5157aaaa [./command.sh $SOURCE $TARGET]</span></div><div><br></=
div><div>There&#39;s not presently logic in SCons to delete target files if=
 the associated action yields an error.</div><div><br></div><div>I think wh=
at you want is equivalent to makes .DELETE_ON_FAILURE, there&#39;s actually=
 a SO question on this:</div><div><a href=3D"https://stackoverflow.com/ques=
tions/29546276/scons-delete-target-on-failure-of-any-action" target=3D"_bla=
nk">https://stackoverflow.com/questions/29546276/scons-delete-target-on-fai=
lure-of-any-action</a></div><div><br></div><div>Please go ahead and file an=
 enhancement request to add equivalent to=C2=A0DELETE_ON_FAILURE, please in=
clude your reproducer scripts.</div><div><br></div><div>-Bill</div></div><b=
r><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On Wed, =
Jul 16, 2025 at 10:44=E2=80=AFAM Tal Dayan &lt;<a href=3D"mailto:tal@zapta.=
com" target=3D"_blank">[email protected]</a>&gt; wrote:<br></div><blockquote cl=
ass=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid=
 rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr">Looking at the end sta=
te of scons after invocation #3, the actual md5 of file2 doesn&#39;t match =
its md5 in the dblite.<div><br></div><div><a href=3D"https://i.imgur.com/NG=
co3yQ.png" target=3D"_blank">https://i.imgur.com/NGco3yQ.png</a></div></div=
><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On We=
d, Jul 16, 2025 at 10:33=E2=80=AFAM Tal Dayan &lt;<a href=3D"mailto:tal@zap=
ta.com" target=3D"_blank">[email protected]</a>&gt; wrote:<br></div><blockquote=
 class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px so=
lid rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr">Hi Keith, I updated=
 the example files here=C2=A0<a href=3D"https://github.com/FPGAwars/apio/is=
sues/676" target=3D"_blank">https://github.com/FPGAwars/apio/issues/676</a>=
<div><br></div><div>They now include the md5 of the files and a dump of=C2=
=A0<span style=3D"font-variant-ligatures:no-common-ligatures;color:rgb(0,0,=
0);font-family:Menlo;font-size:12px">.sconsign.dblite</span></div>





</div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">=
On Wed, Jul 16, 2025 at 10:08=E2=80=AFAM Keith Prussing &lt;<a href=3D"mail=
to:[email protected]" target=3D"_blank">[email protected]</a>&gt; w=
rote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0p=
x 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">I suspect =
it&#39;s because `file1` has the same hash in the<br>
.sconsign.dblite as the last &quot;good&quot; build (i.e. the first one). T=
hus<br>
you get the line &quot;scons: `file2&#39; is up to date.&quot; on the third=
 run.<br>
However, I am not an expert in the specifics of SCons&#39; hashing<br>
methods.<br>
<br>
On Wed, Jul 16, 2025 at 12:38=E2=80=AFPM Tal Dayan &lt;<a href=3D"mailto:ta=
[email protected]" target=3D"_blank">[email protected]</a>&gt; wrote:<br>
&gt;<br>
&gt; Hi all,<br>
&gt;<br>
&gt; We encountered this problem with the nextpnr tool and created here a s=
mall and independent example that demonstrates it.<br>
&gt;<br>
&gt; In the example below, a shell script &#39;command.sh&#39; reads the so=
urce file &#39;file1&#39; and writes it to the target file &#39;file2&#39;.=
 However, if the<br>
&gt; source file starts with &#39;bad&#39; it exits with an error code, *af=
ter* creating the target file.<br>
&gt;<br>
&gt; The script `run.sh&#39;, runs scons three times with these values of t=
he source file file1 &#39;good&#39;, &#39;bad&#39;, and &#39;good&#39;.=C2=
=A0 The expectation is that after the third scons run, file2 should contain=
 the value &#39;good&#39; but it contains the value &#39;bad&#39;.<br>
&gt;<br>
&gt; Do we miss anything or is it simply a bug?<br>
&gt;<br>
&gt; SConstruct:<br>
&gt;<br>
&gt; ----------------------------------------------<br>
&gt;<br>
&gt; # SCons environment<br>
&gt;<br>
&gt; env =3D Environment()<br>
&gt;<br>
&gt;<br>
&gt; # Copy file1 =E2=86=92 file2 using command.sh<br>
&gt;<br>
&gt; # Inject an error if file1 starts with &#39;bad&quot;<br>
&gt;<br>
&gt; file2 =3D env.Command(<br>
&gt;<br>
&gt;=C2=A0 =C2=A0 =C2=A0target=3D&#39;file2&#39;,<br>
&gt;<br>
&gt;=C2=A0 =C2=A0 =C2=A0source=3D&#39;file1&#39;,<br>
&gt;<br>
&gt;=C2=A0 =C2=A0 =C2=A0action=3D&#39;./command.sh $SOURCE &gt; $TARGET&#39=
;<br>
&gt;<br>
&gt; )<br>
&gt;<br>
&gt;<br>
&gt; # Make &#39;file2&#39; the default target<br>
&gt;<br>
&gt; Default(file2)<br>
&gt;<br>
&gt; ----------------------------------------------<br>
&gt;<br>
&gt;<br>
&gt; command.sh:<br>
&gt;<br>
&gt; ----------------------------------------------<br>
&gt;<br>
&gt; #!/bin/bash<br>
&gt;<br>
&gt; # Usage: ./command input &gt; output<br>
&gt;<br>
&gt;<br>
&gt; # Read from the first argument and copy to stdout<br>
&gt;<br>
&gt; cat &quot;$1&quot;<br>
&gt;<br>
&gt;<br>
&gt; # If the input file starts with &#39;bad&#39;, inject an error AFTER c=
reating the output file.<br>
&gt;<br>
&gt;<br>
&gt; first_line=3D$(head -n 1 &quot;$1&quot;)<br>
&gt;<br>
&gt;<br>
&gt; if [[ &quot;$first_line&quot; =3D=3D bad* ]]; then<br>
&gt;<br>
&gt;=C2=A0 =C2=A0exit 1<br>
&gt;<br>
&gt; fi<br>
&gt;<br>
&gt;<br>
&gt; exit 0<br>
&gt;<br>
&gt; ----------------------------------------------<br>
&gt;<br>
&gt;<br>
&gt;<br>
&gt; run.sh<br>
&gt;<br>
&gt; ----------------------------------------------<br>
&gt;<br>
&gt; #!/bin/bash<br>
&gt;<br>
&gt;<br>
&gt; # Clean up.<br>
&gt;<br>
&gt; rm -f .sconsign.dblite<br>
&gt;<br>
&gt; rm -f file[12]<br>
&gt;<br>
&gt;<br>
&gt; echo<br>
&gt;<br>
&gt; echo &quot;---- Iteration 1: file1 =3D &#39;good&#39;&quot;<br>
&gt;<br>
&gt; echo &quot;good&quot; &gt; file1<br>
&gt;<br>
&gt; scons<br>
&gt;<br>
&gt; echo<br>
&gt;<br>
&gt;<br>
&gt; echo &quot;File1&quot;<br>
&gt;<br>
&gt; cat -n file1<br>
&gt;<br>
&gt;<br>
&gt; echo &quot;File2&quot;<br>
&gt;<br>
&gt; cat -n file2<br>
&gt;<br>
&gt;<br>
&gt;<br>
&gt; echo<br>
&gt;<br>
&gt; echo &quot;---- Iteration 2: file1 =3D &#39;bad&#39;&quot;<br>
&gt;<br>
&gt; echo &quot;bad&quot; &gt; file1<br>
&gt;<br>
&gt; cat -n file1<br>
&gt;<br>
&gt; scons<br>
&gt;<br>
&gt; echo<br>
&gt;<br>
&gt;<br>
&gt; echo &quot;File1&quot;<br>
&gt;<br>
&gt; cat -n file1<br>
&gt;<br>
&gt;<br>
&gt; echo &quot;File2&quot;<br>
&gt;<br>
&gt; cat -n file2<br>
&gt;<br>
&gt;<br>
&gt; echo<br>
&gt;<br>
&gt; echo &quot;---- Iteration 3: file1 =3D &#39;good&#39;&quot;<br>
&gt;<br>
&gt; echo &quot;good&quot; &gt; file1<br>
&gt;<br>
&gt; cat -n file1<br>
&gt;<br>
&gt; scons<br>
&gt;<br>
&gt; echo<br>
&gt;<br>
&gt;<br>
&gt; echo &quot;File1&quot;<br>
&gt;<br>
&gt; cat -n file1<br>
&gt;<br>
&gt;<br>
&gt; echo &quot;File2&quot;<br>
&gt;<br>
&gt; cat -n file2<br>
&gt;<br>
&gt; ----------------------------------------------<br>
&gt;<br>
&gt;<br>
&gt;<br>
&gt; Run log:<br>
&gt;<br>
&gt; ----------------------------------------------<br>
&gt;<br>
&gt; $ ./run.sh<br>
&gt;<br>
&gt;<br>
&gt; ---- Iteration 1: file1 =3D &#39;good&#39;<br>
&gt;<br>
&gt; scons: Reading SConscript files ...<br>
&gt;<br>
&gt; scons: done reading SConscript files.<br>
&gt;<br>
&gt; scons: Building targets ...<br>
&gt;<br>
&gt; ./command.sh file1 &gt; file2<br>
&gt;<br>
&gt; scons: done building targets.<br>
&gt;<br>
&gt;<br>
&gt; File1<br>
&gt;<br>
&gt;=C2=A0 =C2=A0 =C2=A0 1 good<br>
&gt;<br>
&gt; File2<br>
&gt;<br>
&gt;=C2=A0 =C2=A0 =C2=A0 1 good<br>
&gt;<br>
&gt;<br>
&gt; ---- Iteration 2: file1 =3D &#39;bad&#39;<br>
&gt;<br>
&gt;=C2=A0 =C2=A0 =C2=A0 1 bad<br>
&gt;<br>
&gt; scons: Reading SConscript files ...<br>
&gt;<br>
&gt; scons: done reading SConscript files.<br>
&gt;<br>
&gt; scons: Building targets ...<br>
&gt;<br>
&gt; ./command.sh file1 &gt; file2<br>
&gt;<br>
&gt; scons: *** [file2] Error 1<br>
&gt;<br>
&gt; scons: building terminated because of errors.<br>
&gt;<br>
&gt;<br>
&gt; File1<br>
&gt;<br>
&gt;=C2=A0 =C2=A0 =C2=A0 1 bad<br>
&gt;<br>
&gt; File2<br>
&gt;<br>
&gt;=C2=A0 =C2=A0 =C2=A0 1 bad<br>
&gt;<br>
&gt;<br>
&gt; ---- Iteration 1: file1 =3D &#39;good&#39;<br>
&gt;<br>
&gt;=C2=A0 =C2=A0 =C2=A0 1 good<br>
&gt;<br>
&gt; scons: Reading SConscript files ...<br>
&gt;<br>
&gt; scons: done reading SConscript files.<br>
&gt;<br>
&gt; scons: Building targets ...<br>
&gt;<br>
&gt; scons: `file2&#39; is up to date.<br>
&gt;<br>
&gt; scons: done building targets.<br>
&gt;<br>
&gt;<br>
&gt; File1<br>
&gt;<br>
&gt;=C2=A0 =C2=A0 =C2=A0 1 good<br>
&gt;<br>
&gt; File2<br>
&gt;<br>
&gt;=C2=A0 =C2=A0 =C2=A0 1 bad<br>
&gt;<br>
&gt; ----------------------------------------------<br>
&gt;<br>
&gt; _______________________________________________<br>
&gt; Scons-users mailing list<br>
&gt; <a href=3D"mailto:[email protected]" target=3D"_blank">Scons-users=
@scons.org</a><br>
&gt; <a href=3D"https://pairlist4.pair.net/mailman/listinfo/scons-users" re=
l=3D"noreferrer" target=3D"_blank">https://pairlist4.pair.net/mailman/listi=
nfo/scons-users</a><br>
<br>
<br>
<br>
-- <br>
Keith Prussing<br>
_______________________________________________<br>
Scons-users mailing list<br>
<a href=3D"mailto:[email protected]" target=3D"_blank">Scons-users@scon=
s.org</a><br>
<a href=3D"https://pairlist4.pair.net/mailman/listinfo/scons-users" rel=3D"=
noreferrer" target=3D"_blank">https://pairlist4.pair.net/mailman/listinfo/s=
cons-users</a><br>
</blockquote></div>
</blockquote></div>
_______________________________________________<br>
Scons-users mailing list<br>
<a href=3D"mailto:[email protected]" target=3D"_blank">Scons-users@scon=
s.org</a><br>
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noreferrer" target=3D"_blank">https://pairlist4.pair.net/mailman/listinfo/s=
cons-users</a><br>
</blockquote></div>
_______________________________________________<br>
Scons-users mailing list<br>
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s.org</a><br>
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noreferrer" target=3D"_blank">https://pairlist4.pair.net/mailman/listinfo/s=
cons-users</a><br>
</blockquote></div>
_______________________________________________<br>
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noreferrer" target=3D"_blank">https://pairlist4.pair.net/mailman/listinfo/s=
cons-users</a><br>
</blockquote></div>
</blockquote></div>
</blockquote></div>
_______________________________________________<br>
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s.org</a><br>
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noreferrer" target=3D"_blank">https://pairlist4.pair.net/mailman/listinfo/s=
cons-users</a><br>
</blockquote></div>

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