sage-env, sage-build-env: No longer allow environment variables CC, CFLAGS, ... to override configured variables

[mkoeppe]

After this change, only ./configure will pick up these variables from the environment.

This is an incompatible change to long-standing behavior of Sage, but the change will bring the build system in line with autotools and avoid confusing failures.

Overriding CC, CFLAGS, ... will still be possible by passing them as makefile variables on the command line (make CFLAGS="-gggg" build)

(previous related tickets: #29507, #23570, #30375)

CC: @kliem @dimpase

Component: build

Author: Jonathan Kliem

Branch/Commit: public/32436 @ 1e5da46

Reviewer: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/32436

[mkoeppe]

Description changed:

--- 
+++ 
@@ -2,3 +2,4 @@
 
 Bonus points if overriding CC, CFLAGS, ... will still be possible by passing them as makefile variables on the command line (`make CFLAGS="-gggg" build`)
 
+(previous related tickets: #29507, #23570, #30375)

[dimpase]

comment:2

so e.g. FC=footran ./configure
will have no effect?

This will need a bit of testing, as, iirc, some packages really need env vars set.

[mkoeppe]

comment:3

No, FC=footran ./configure (or ./configure FC=footran) will of course use the variable.

But FC=footran make will not use the variable (except if it invokes ./configure --recheck).

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,3 +1,5 @@
+After this change, only `./configure` will pick up these variables from the environment.
+
 This is an incompatible change to long-standing behavior of Sage, but the change will bring the build system in line with autotools and avoid confusing failures such as the one reported in: https://groups.google.com/g/sage-release/c/WX3m7T8-SeM/m/It62bpVpAgAJ
 
 Bonus points if overriding CC, CFLAGS, ... will still be possible by passing them as makefile variables on the command line (`make CFLAGS="-gggg" build`)

[mkoeppe]

comment:4

Replying to @dimpase:

some packages really need env vars set.

Of course, that's why our build scripts (sage-env, sage-build-env) set them (to the configured values)

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,6 +1,6 @@
 After this change, only `./configure` will pick up these variables from the environment.
 
-This is an incompatible change to long-standing behavior of Sage, but the change will bring the build system in line with autotools and avoid confusing failures such as the one reported in: https://groups.google.com/g/sage-release/c/WX3m7T8-SeM/m/It62bpVpAgAJ
+This is an incompatible change to long-standing behavior of Sage, but the change will bring the build system in line with autotools and avoid confusing failures.
 
 Bonus points if overriding CC, CFLAGS, ... will still be possible by passing them as makefile variables on the command line (`make CFLAGS="-gggg" build`)
 

[kliem]

Commit: 3436a5b

[kliem]

Author: Jonathan Kliem

[kliem]

Branch: public/32436

[kliem]

New commits:

3436a5b

do not overwrite configured CC, CFLAGS etc. unless as optional make argument

[kliem]

Description changed:

--- 
+++ 
@@ -2,6 +2,6 @@
 
 This is an incompatible change to long-standing behavior of Sage, but the change will bring the build system in line with autotools and avoid confusing failures.
 
-Bonus points if overriding CC, CFLAGS, ... will still be possible by passing them as makefile variables on the command line (`make CFLAGS="-gggg" build`)
+Overriding CC, CFLAGS, ... will still be possible by passing them as makefile variables on the command line (`make CFLAGS="-gggg" build`)
 
 (previous related tickets: #29507, #23570, #30375)

[mkoeppe]

comment:8

Looking good except that this comment:

 
 # The compilers are set in order of priority by
-# 1) environment variables
+# 1) given as make arguments (e.g. ``make CC=gcc``)
 # 2) compiler installed by sage
-# 3) compiler set at configuration time 
+# 3) compiler set at configuration time
 if [ -z "$CC" ]; then

is not quite accurate. Better to distinguish the cases sage -buildsh (or make) vs other uses

[kliem]

comment:9

Replying to @mkoeppe:

Looking good except that this comment:

 
 # The compilers are set in order of priority by
-# 1) environment variables
+# 1) given as make arguments (e.g. ``make CC=gcc``)
 # 2) compiler installed by sage
-# 3) compiler set at configuration time 
+# 3) compiler set at configuration time
 if [ -z "$CC" ]; then

is not quite accurate. Better to distinguish the cases sage -buildsh (or make) vs other uses

I don't understand. What do you think the correct comment would be?

Currently, $CC, $FC, $CXX are picked up for any use of sage -... and make ....
The first modification is only possible with make (or in sage --buildsh and sage -sh after having started it).

[mkoeppe]

comment:10

Stalled in needs_review or needs_info; likely won't make it into Sage 9.5.