abd7a47461
* guix/scripts/build.scm (package-dependents/spec)
(package-toolchain-rewriting, transform-package-toolchain): New procedures.
(%transformations): Add it.
(%transformation-options, show-transformation-options-help): Add
'--with-c-toolchain'.
* tests/scripts-build.scm (depends-on-toolchain?): New procedure.
("options->transformation, with-c-toolchain")
("options->transformation, with-c-toolchain twice")
New test.
("options->transformation, with-c-toolchain, no effect"): New tests.
* doc/guix.texi (Package Transformation Options): Document it.