PKGBUILD: handle arch specific attributes

This introduces support for architecture-specific conflicts, depends,
optdepends, makedepends, replaces, and conflicts by appending "_$CARCH"
to the array name. For example, in the global section:

  arch=('i686' 'x86_64')
  depends=('foo')
  depends_x86_64=('bar')

This will generate depends of 'foo' and 'bar' on x86_64, but only 'foo'
on i686. Moreover, this is supported in the package functions with the
same heuristics as the generic names, e.g.

  ...
  arch=('i686' 'x86_64')
  depends=('foo')
  ...

  package_somepkg() {
    depends_x86_64=('bar')

    ...
  }

Again, will cause x86_64 to have depends of 'foo' and 'bar', but only
'foo' for i686.

doc/PKGBUILD.5.txt

@@ -183,17 +183,26 @@ If the dependency name appears to be a library (ends with .so), makepkg will
 try to find a binary that depends on the library in the built package and
 append the version needed by the binary. Appending the version yourself
 disables automatic detection.
++
+Additional architecture-specific depends can be added by appending an
+underscore and the architecture name e.g., 'depends_x86_64=()'.
 
 *makedepends (array)*::
 	An array of packages this package depends on to build but are not
 	needed at runtime. Packages in this list follow the same format as
 	depends.
++
+Additional architecture-specific makedepends can be added by appending an
+underscore and the architecture name e.g., 'makedepends_x86_64=()'.
 
 *checkdepends (array)*::
 	An array of packages this package depends on to run its test suite
 	but are not needed at runtime. Packages in this list follow the same
 	format as depends. These dependencies are only considered when the
 	check() function is present and is to be run by makepkg.
++
+Additional architecture-specific checkdepends can be added by appending an
+underscore and the architecture name e.g., 'checkdepends_x86_64=()'.
 
 *optdepends (array)*::
 	An array of packages (and accompanying reasons) that are not essential for
@@ -203,12 +212,18 @@ disables automatic detection.
 	for specifying optdepends is:
 
 	optdepends=('fakeroot: for makepkg usage as normal user')
++
+Architecture-specific optdepends can be added by appending an underscore and
+the architecture name e.g., 'optdepends_x86_64=()'.
 
 *conflicts (array)*::
 	An array of packages that will conflict with this package (i.e. they
 	cannot both be installed at the same time). This directive follows the
 	same format as depends. Versioned conflicts are supported using the
 	operators as described in `depends`.
++
+Additional architecture-specific conflicts can be added by appending an
+underscore and the architecture name e.g., 'conflicts_x86_64=()'.
 
 *provides (array)*::
 	An array of ``virtual provisions'' this package provides. This allows
@@ -224,6 +239,9 @@ only specific versions of a package may be provided.
 If the provision name appears to be a library (ends with .so), makepkg will
 try to find the library in the built package and append the correct
 version. Appending the version yourself disables automatic detection.
++
+Additional architecture-specific provides can be added by appending an
+underscore and the architecture name e.g., 'provides_x86_64=()'.
 
 *replaces (array)*::
 	An array of packages this package should replace. This can be used
@@ -234,6 +252,9 @@ version. Appending the version yourself disables automatic detection.
 +
 Sysupgrade is currently the only pacman operation that utilizes this field.
 A normal sync or upgrade will not use its value.
++
+Additional architecture-specific replaces can be added by appending an
+underscore and the architecture name e.g., 'replaces_x86_64=()'.
 
 *options (array)*::
 	This array allows you to override some of makepkg's default behavior

scripts/makepkg.sh.in

@@ -1475,6 +1475,24 @@ source_safe() {
 	shopt -s extglob
 }
 
+merge_arch_attrs() {
+	local attr supported_attrs=(
+		provides conflicts depends replaces optdepends
+		makedepends checkdepends)
+
+	for attr in "${supported_attrs[@]}"; do
+		eval "$attr+=(\"\${${attr}_$CARCH[@]}\")"
+	done
+
+	# ensure that calling this function is idempotent.
+	unset -v "${supported_attrs[@]/%/_$CARCH}"
+}
+
+source_buildfile() {
+	source_safe "$@"
+	merge_arch_attrs
+}
+
 run_function_safe() {
 	local restoretrap
 
@@ -1893,6 +1911,8 @@ write_pkginfo() {
 	local size="$(@DUPATH@ @DUFLAGS@)"
 	size="$(( ${size%%[^0-9]*} * 1024 ))"
 
+	merge_arch_attrs
+
 	msg2 "$(gettext "Generating %s file...")" ".PKGINFO"
 	printf "# Generated by makepkg %s\n" "$makepkg_version"
 	printf "# using %s\n" "$(fakeroot -v)"
@@ -2359,13 +2379,24 @@ lint_arch() {
 }
 
 lint_provides() {
-	local list name provides_list ret=0
+	local a list name provides_list ret=0
 
 	provides_list=("${provides[@]}")
+	for a in "${arch[@]}"; do
+		array_build list "provides_$a"
+		provides_list+=("${list[@]}")
+	done
+
 	for name in "${pkgname[@]}"; do
 		if extract_function_var "package_$name" provides 1 list; then
 			provides_list+=("${list[@]}")
 		fi
+
+		for a in "${arch[@]}"; do
+			if extract_function_var "package_$name" "provides_$a" 1 list; then
+				provides_list+=("${list[@]}")
+			fi
+		done
 	done
 
 	for provide in "${provides_list[@]}"; do
@@ -2399,13 +2430,24 @@ lint_backup() {
 }
 
 lint_optdepends() {
-	local list name optdepends_list ret=0
+	local a list name optdepends_list ret=0
 
 	optdepends_list=("${optdepends[@]}")
+	for a in "${arch[@]}"; do
+		array_build list "optdepends_$a"
+		optdepends_list+=("${list[@]}")
+	done
+
 	for name in "${pkgname[@]}"; do
 		if extract_function_var "package_$name" optdepends 1 list; then
 			optdepends_list+=("${list[@]}")
 		fi
+
+		for a in "${arch[@]}"; do
+			if extract_function_var "package_$name" "optdepends_$a" 1 list; then
+				optdepends_list+=("${list[@]}")
+			fi
+		done
 	done
 
 	for name in "${optdepends_list[@]}"; do
@@ -3161,7 +3203,7 @@ else
 	if [[ ${BUILDFILE:0:1} != "/" ]]; then
 		BUILDFILE="$startdir/$BUILDFILE"
 	fi
-	source_safe "$BUILDFILE"
+	source_buildfile "$BUILDFILE"
 fi
 
 # set defaults if they weren't specified in buildfile