sage: Determine SAGE_LOCAL, SAGE_ROOT via sage-config if it exists

[mkoeppe]

We reduce the runtime dependency of sage on sage-env-config.

We query sage-config (installed by sage_conf, which has a dependency on our python3 package) for the values of SAGE_LOCAL and SAGE_ROOT. sage-config must be in the same directory as $0.

This allows the installed sage script to be invoked directly from $SAGE_LOCAL/bin in an environment without SAGE_... variables, restoring what was previously implemented in #25486.

Also, we move sourcing of sage-env-config (but not sage-env!) earlier in the sage script.
This is so that commands such as $SAGE_LOCAL/bin/sage --root work correctly.

Follow-up tickets:

• Make $SAGE_LOCAL/bin/sage work again from any directory, in an environment without SAGE_* variables, following symlinks #30888 resolve symlinks so it even works for symlinks to $SAGE_LOCAL/bin/sage
• src/bin/sage-env: Make sure $SAGE_VENV/bin is at the beginning of the PATH #30013 set SAGE_VENV too
• remove the build-time dependency of the sage distribution on src/bin/sage-env-config

CC: @kiwifb @orlitzky @jhpalmieri @antonio-rojas @seblabbe

Component: build

Keywords: sd111

Author: Matthias Koeppe

Branch/Commit: eb3793e

Reviewer: Dima Pasechnik, François Bissey

Issue created by migration from https://trac.sagemath.org/ticket/29852

[mkoeppe]

Description changed:

--- 
+++ 
@@ -3,5 +3,6 @@
 * the runtime dependency of sagelib on `sage-env-config`.
 
 Instead we use `sage-config` from `sage_conf` (which has a dependency on our `python3` package, of course).
+In this ticket, we do this for `SAGE_LOCAL` and `SAGE_ROOT`.
 
 

[mkoeppe]

Changed dependencies from #29825 to #29850

[mkoeppe]

Changed dependencies from #29850 to #22731

[mkoeppe]

Branch: u/mkoeppe/get_rid_of_sage_env_config

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,8 +1,15 @@
-We remove 
-* the build-time dependency of the sage distribution on `src/bin/sage-env-config` 
-* the runtime dependency of sagelib on `sage-env-config`.
+We reduce the runtime dependency of `sage` on `sage-env-config`.
 
-Instead we use `sage-config` from `sage_conf` (which has a dependency on our `python3` package, of course).
-In this ticket, we do this for `SAGE_LOCAL` and `SAGE_ROOT`.
+We query `sage-config` from `sage_conf` (which has a dependency on our `python3` package, of course) for the values of `SAGE_LOCAL` and `SAGE_ROOT`. `sage-config` must be in the same directory as $0.
+
+This allows the installed `sage` script to be invoked directly from `$SAGE_LOCAL/bin` in an environment without `SAGE_...` variables, restoring what was previously implemented in #25486.
+
+Also, we move sourcing of `sage-env-config` (but not `sage-env`!) earlier in the `sage` script. 
+This is so that commands such as `sage --root` work correctly.
+
+Follow-up tickets:
+- #30888 resolve symlinks so it even works for symlinks to `$SAGE_LOCAL/bin/sage`
+- #30013 set `SAGE_VENV` too
+- remove the build-time dependency of the sage distribution on `src/bin/sage-env-config` 
 
 

[mkoeppe]

Last 10 new commits:

8f88709	src/bin/sage: Only source sage-env-config if it exists
ab2655e	src/bin/sage: Use python3 etc. from PATH instead of using SAGE_LOCAL
4577f37	src/bin/sage-env: Make sage-env-config optional
c35c170	sage.env: Add SAGE_VENV
c585d94	src/sage: Replace some SAGE_LOCAL by SAGE_VENV
2fd195f	src/bin/sage: Fix reference to trac ticket
f3b7a9c	src/sage/env.py: Add documentation
995af9f	Merge branch 't/22731/22731' into t/29852/get_rid_of_sage_env_config
2bce7b8	src/bin/sage: Find SAGE_ROOT, SAGE_LOCAL from sage-config
9810f49	src/bin/sage: Determine SAGE_ROOT, SAGE_LOCAL earlier

[mkoeppe]

Commit: 9810f49

[mkoeppe]

Description changed:

--- 
+++ 
@@ -5,7 +5,7 @@
 This allows the installed `sage` script to be invoked directly from `$SAGE_LOCAL/bin` in an environment without `SAGE_...` variables, restoring what was previously implemented in #25486.
 
 Also, we move sourcing of `sage-env-config` (but not `sage-env`!) earlier in the `sage` script. 
-This is so that commands such as `sage --root` work correctly.
+This is so that commands such as `$SAGE_LOCAL/bin/sage --root` work correctly.
 
 Follow-up tickets:
 - #30888 resolve symlinks so it even works for symlinks to `$SAGE_LOCAL/bin/sage`

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,6 +1,6 @@
 We reduce the runtime dependency of `sage` on `sage-env-config`.
 
-We query `sage-config` from `sage_conf` (which has a dependency on our `python3` package, of course) for the values of `SAGE_LOCAL` and `SAGE_ROOT`. `sage-config` must be in the same directory as $0.
+We query `sage-config` (installed by `sage_conf`, which has a dependency on our `python3` package) for the values of `SAGE_LOCAL` and `SAGE_ROOT`. `sage-config` must be in the same directory as $0.
 
 This allows the installed `sage` script to be invoked directly from `$SAGE_LOCAL/bin` in an environment without `SAGE_...` variables, restoring what was previously implemented in #25486.
 

[dimpase]

comment:10

lgtm

[dimpase]

Reviewer: Dima Pasechnik

[mkoeppe]

comment:11

Thanks!