| Message ID | c09add9a59c5afc09926.1402085578@localhost |
|---|---|
| State | Superseded |
| Headers | show |
Thomas, All, On 2014-06-06 22:12 +0200, Thomas De Schampheleire spake thusly: > As the rules with respect to variable and function references and the need > for single or double dollar signs are not trivial, add a comment in > pkg-generic.mk describing them. > > Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com> Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr> Regards, Yann E. MORIN. > --- > v3: expand exception for pkgdir and pkgname > v2: clarify exception for pkgdir and pkgname > > package/pkg-generic.mk | 23 +++++++++++++++++++++++ > 1 files changed, 23 insertions(+), 0 deletions(-) > > diff -r b1861ead4977 -r c09add9a59c5 package/pkg-generic.mk > --- a/package/pkg-generic.mk Thu May 08 21:53:48 2014 +0200 > +++ b/package/pkg-generic.mk Sat May 10 10:04:45 2014 +0200 > @@ -269,6 +269,29 @@ > # argument 3 is the uppercase package name, without the HOST_ prefix > # for host packages > # argument 4 is the type (target or host) > +# > +# Note about variable and function references: inside all blocks that are > +# evaluated with $(eval), which includes all 'inner-xxx-package' blocks, > +# specific rules apply with respect to variable and function references. > +# - Numbered variables (parameters to the block) can be referenced with a single > +# dollar sign: $(1), $(2), $(3), etc. > +# - pkgdir and pkgname should be referenced with a single dollar sign too. These > +# functions rely on 'the most recently parsed makefile' which is supposed to > +# be the package .mk file. If we defer the evaluation of these functions using > +# double dollar signs, then they may be evaluated too late, when other > +# makefiles have already been parsed. One specific case is when $$(pkgdir) is > +# assigned to a variable using deferred evaluation with '=' and this variable > +# is used in a target rule outside the eval'ed inner block. In this case, the > +# pkgdir will be that of the last makefile parsed by buildroot, which is not > +# the expected value. This mechanism is for example used for the TARGET_PATCH > +# rule. > +# - All other variables should be referenced with a double dollar sign: > +# $$(TARGET_DIR), $$($(2)_VERSION), etc. Also all make functions should be > +# referenced with a double dollar sign: $$(subst), $$(call), $$(filter-out), > +# etc. This rule ensures that these variables and functions are only expanded > +# during the $(eval) step, and not earlier. Otherwise, unintuitive and > +# undesired behavior occurs with respect to these variables and functions. > +# > ################################################################################ > > define inner-generic-package
Dear Thomas De Schampheleire, On Fri, 06 Jun 2014 22:12:58 +0200, Thomas De Schampheleire wrote: > As the rules with respect to variable and function references and the need > for single or double dollar signs are not trivial, add a comment in > pkg-generic.mk describing them. > > Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com> Reviewed-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
diff -r b1861ead4977 -r c09add9a59c5 package/pkg-generic.mk --- a/package/pkg-generic.mk Thu May 08 21:53:48 2014 +0200 +++ b/package/pkg-generic.mk Sat May 10 10:04:45 2014 +0200 @@ -269,6 +269,29 @@ # argument 3 is the uppercase package name, without the HOST_ prefix # for host packages # argument 4 is the type (target or host) +# +# Note about variable and function references: inside all blocks that are +# evaluated with $(eval), which includes all 'inner-xxx-package' blocks, +# specific rules apply with respect to variable and function references. +# - Numbered variables (parameters to the block) can be referenced with a single +# dollar sign: $(1), $(2), $(3), etc. +# - pkgdir and pkgname should be referenced with a single dollar sign too. These +# functions rely on 'the most recently parsed makefile' which is supposed to +# be the package .mk file. If we defer the evaluation of these functions using +# double dollar signs, then they may be evaluated too late, when other +# makefiles have already been parsed. One specific case is when $$(pkgdir) is +# assigned to a variable using deferred evaluation with '=' and this variable +# is used in a target rule outside the eval'ed inner block. In this case, the +# pkgdir will be that of the last makefile parsed by buildroot, which is not +# the expected value. This mechanism is for example used for the TARGET_PATCH +# rule. +# - All other variables should be referenced with a double dollar sign: +# $$(TARGET_DIR), $$($(2)_VERSION), etc. Also all make functions should be +# referenced with a double dollar sign: $$(subst), $$(call), $$(filter-out), +# etc. This rule ensures that these variables and functions are only expanded +# during the $(eval) step, and not earlier. Otherwise, unintuitive and +# undesired behavior occurs with respect to these variables and functions. +# ################################################################################ define inner-generic-package
As the rules with respect to variable and function references and the need for single or double dollar signs are not trivial, add a comment in pkg-generic.mk describing them. Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com> --- v3: expand exception for pkgdir and pkgname v2: clarify exception for pkgdir and pkgname package/pkg-generic.mk | 23 +++++++++++++++++++++++ 1 files changed, 23 insertions(+), 0 deletions(-)