Repeated configure run with gcc already installed treats gcc as not installed

[jdemeyer]

If ./configure detects an existing GCC installed in Sage (SAGE_INSTALL_GCC=exists) then it should keep gcc selected among the packages to be installed as part of the distribution. Otherwise it basically deselects gcc which is the wrong thing to do (with any package).

Depends on #25857

CC: @embray

Component: build

Author: Erik Bray

Branch/Commit: 5d0a981

Reviewer: Volker Braun, Julian Rüth, Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/25188

[jdemeyer]

Attachment: Makefile.gz

Auto-generated build/make/Makefile

[embray]

comment:3

I don't think this is any different from how it used to work. For each package, there is a variable in the Makefile called inst_<pkgname>. If the package should be installed (particularly as a dependency of another package) its inst_<pkgname> should point to the real stamp file for that package under SAGE_SPKG_INSTS. However, if the package is not being installed in Sage (i.e. due to a configure check) then its inst_<pkgname> just points to .dummy. But explicit build rules for that package are still added to the Makefile, so if you run make gfortran you can still install the gfortran package, overriding the configure-time determination.

I'm not 100% convinced that's the best behavior (I think if you want to override a configure-based selection you should have to actually re-run configure). But that's how it always worked until now.

[embray]

comment:4

I think the problem has more to do with the oddities of how gcc is being handled, especially since #24703.

I was confused because you wrote that "gcc is also installed", but in your Makefile it has gcc in DUMMY_PACKAGES implying that it was not selected for installation. Yet all the packages have $(SAGE_LOCAL)/bin/gcc as dependencies implying that it was installed at some point.

I think that what #24703 missed is that even if $SAGE_INSTALL_GCC = exists it needs to be setting needs_to_install_gcc = yes (this doesn't actually mean it will reinstall gcc if it isn't necessary to--this just means gcc is selected for possible installation in Sage, pending checking of its prerequisites by make). Since that isn't happening, the build system gets into a funny state where Sage's gcc is installed, but the build system doesn't really think it should be.

[embray]

Branch: u/embray/build/ticket-25188

[embray]

Author: Erik Bray

[embray]

Commit: 2f97ecf

[embray]

comment:5

I'm not positive since you weren't clear on the actual symptoms, but I think this should fix the basic problem (I'm guessing that it was a complaint about no target for $(SAGE_LOCAL)/bin/gcc).

---

New commits:

2f97ecf

should still set need_to_install_gcc=yes in configure if Sage's gcc is already installed

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

0baf862

build/make/Makefile should be rebuild with build/make/Makefile.in is updated

[sagetrac-git]

Changed commit from 2f97ecf to 0baf862

[jdemeyer]

comment:7

I haven't reviewed the patch, but it would really be useful if DEBUG_RULES=1 would show everything that ends up in the Makefile. In particular, the expansions of the inst_FOO variables are currently missing.

This is precisely the sort of thing why I opposed #21524: the Makefile rules are too obscure to understand what is broken.

[jdemeyer]

comment:8

Replying to @embray:

I was confused because you wrote that "gcc is also installed", but in your Makefile it has gcc in DUMMY_PACKAGES implying that it was not selected for installation. Yet all the packages have $(SAGE_LOCAL)/bin/gcc as dependencies implying that it was installed at some point.

Yes, I meant "gcc has been installed at some point in the past". configure correctly detects that gfortran should not be installed, but it's still being installed anyway.

[jdemeyer]

comment:9

Replying to @embray:

if you run make gfortran you can still install the gfortran package, overriding the configure-time determination.

To be clear: this is not what I'm doing. gfortran is build during the normal build process.

[jdemeyer]

comment:10

Never mind, user error...

[embray]

comment:11

Replying to @jdemeyer:

I haven't reviewed the patch, but it would really be useful if DEBUG_RULES=1 would show everything that ends up in the Makefile. In particular, the expansions of the inst_FOO variables are currently missing.

This is precisely the sort of thing why I opposed #21524: the Makefile rules are too obscure to understand what is broken.

I don't think anything's really being obscured here. The old hard-coded makefile didn't expand those variables either so if you suspected something to do with them you've lost nothing.

[embray]

comment:12

Well don't just close it. You've been very vague about what the actual problem is here, though you led me to actually examine the issue closely and this fix actually is the correct thing to do.

If ./configure detects an existing GCC installed in Sage (SAGE_INSTALL_GCC=exists) then it should keep gcc selected among the packages to be installed as part of the distribution. Otherwise it basically deselects gcc which is the wrong thing to do (with any package).

[sagetrac-git]

Changed commit from d71c88f to f062068

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

f062068

fix accidentally removed blank line needed to make debugging output look better

[embray]

comment:34

I had to make a small change over the previous fix, but I'm pretty confident this works. I also had to merge in the fix from #25857 in order to be able to be able to test this at all without breaking things too much.

You can install sage-gcc, then packages that gcc depends on like mpir can be reinstalled and updated as much as you want. This isn't a problem because, in part, all of gcc's dependencies are listed as prerequisite-only.

[embray]

Dependencies: #25857

[dimpase]

comment:36

I suppose this also needs configure tarball and bump...

[embray]

comment:37

It might not need a configure tarball, since this looks like one of those ones that "happens to work" even without rebuilding configure.

[dimpase]

Changed reviewer from Volker Braun, Julian Rüth to Volker Braun, Julian Rüth, Dima Pasechnik

[vbraun]

comment:39

Merge conflict

[dimpase]

comment:41

Replying to @vbraun:
IIRC that work branch was https://github.com/sagemath/sage - but this does not seem to be the case anymore. Please advice where to look.

[dimpase]

comment:42

a trivial merge

[dimpase]

Changed branch from u/embray/build/ticket-25188 to public/build/ticket-25188

[dimpase]

Changed commit from f062068 to 5d0a981

[vbraun]

Changed branch from public/build/ticket-25188 to 5d0a981