[gentoo-pms] [PATCH] Ban empty groups in dependency specifications.

[Ulrich Müller]

The specification for empty groups was originally added to match
historical Portage behaviour, but deviates from the usual convention
that empty OR operations should evaluate to false.

However, Portage was changed in 2011 to treat empty dependency groups
as an error, therefore ebuilds cannot rely on any definite behaviour.
Consequently, empty groups are not used by any ebuild or eclass in the
Gentoo repository.

This is an retroactive change for all EAPIs.

Bug: 370565
---
 dependencies.tex | 26 ++++++++++----------------
 1 file changed, 10 insertions(+), 16 deletions(-)

diff --git a/dependencies.tex b/dependencies.tex
index d9a6f1a..62cd669 100644
--- a/dependencies.tex
+++ b/dependencies.tex
@@ -57,33 +57,33 @@ be surrounded on both sides by whitespace, except at the start and end of the st
 \item A use flag name, optionally preceded by an exclamation mark. Permitted in \t{REQUIRED_USE}.
 \item A simple string. Permitted in \t{RESTRICT} and \t{PROPERTIES}.
 \item An all-of group, which consists of an open parenthesis, followed by whitespace,
-    followed by zero or more of (a dependency item of any kind followed by whitespace), followed
+    followed by one or more of (a dependency item of any kind followed by whitespace), followed
     by a close parenthesis. More formally:
-    \t{all-of} \t{::=} \t{'(' whitespace (item whitespace)* ')'}. Permitted in all specification
+    \t{all-of} \t{::=} \t{'(' whitespace (item whitespace)+ ')'}. Permitted in all specification
     style variables.
 \item An any-of group, which consists of the string \t{||}, followed by whitespace,
-    followed by an open parenthesis, followed by whitespace, followed by zero or more
+    followed by an open parenthesis, followed by whitespace, followed by one or more
     of (a dependency item of any kind followed by whitespace), followed by a close parenthesis.
-    More formally: \t{any-of} \t{::=} \t{'||' whitespace '(' whitespace (item whitespace)* ')'}.
+    More formally: \t{any-of} \t{::=} \t{'||' whitespace '(' whitespace (item whitespace)+ ')'}.
     Permitted in \t{DEPEND}, \t{RDEPEND}, \t{PDEPEND}, \t{LICENSE}, \t{REQUIRED_USE}.
 \item An exactly-one-of group, which consists of the string \t{\textasciicircum\textasciicircum},
     followed by whitespace, followed by an open parenthesis, followed by whitespace, followed by
-    zero or more of (a dependency item of any kind followed by whitespace), followed by a close
+    one or more of (a dependency item of any kind followed by whitespace), followed by a close
     parenthesis. More formally: \t{exactly-one-of} \t{::=} \t{'\textasciicircum\textasciicircum'
-    whitespace '(' whitespace (item whitespace)* ')'}.
+    whitespace '(' whitespace (item whitespace)+ ')'}.
     Permitted in \t{REQUIRED_USE}.
 \item \featurelabel{at-most-one-of} An at-most-one-of group, which consists of the string \t{??},
     followed by whitespace, followed by an open parenthesis, followed by whitespace, followed by
-    zero or more of (a dependency item of any kind followed by whitespace), followed by a close
+    one or more of (a dependency item of any kind followed by whitespace), followed by a close
     parenthesis. More formally: \t{at-most-one-of} \t{::=} \t{'??'\ whitespace '(' whitespace
-    (item whitespace)* ')'}. Permitted in \t{REQUIRED_USE} in EAPIs listed in
+    (item whitespace)+ ')'}. Permitted in \t{REQUIRED_USE} in EAPIs listed in
     table~\ref{tab:at-most-one-of-table} as supporting \t{REQUIRED_USE ??}\ groups.
 \item A use-conditional group, which consists of an optional exclamation mark, followed by
     a use flag name, followed by a question mark, followed by whitespace, followed by
-    an open parenthesis, followed by whitespace, followed by zero or more of (a dependency item
+    an open parenthesis, followed by whitespace, followed by one or more of (a dependency item
     of any kind followed by whitespace), followed by a close parenthesis. More formally:
     \t{use-conditional} \t{::=} \t{'!'?\ flag-name '?'\ whitespace '(' whitespace (item
-    whitespace)* ')'}.
+    whitespace)+ ')'}.
     Permitted in all specification style variables.
 \end{compactitem}
 
@@ -138,8 +138,6 @@ for match purposes.
 In an any-of group, at least one immediate child element must be matched. A blocker is
 considered to be matched if its associated package dependency specification is not matched.
 
-An empty any-of group counts as being matched.
-
 \subsection{Exactly-one-of dependency specifications}
 
 Any use-conditional group that is an immediate child of an exactly-one-of group, if not enabled
@@ -148,8 +146,6 @@ exactly-one-of group for match purposes.
 
 In an exactly-one-of group, exactly one immediate child element must be matched.
 
-An empty exactly-one-of group counts as being matched.
-
 \subsection{At-most-one-of dependency specifications}
 
 Any use-conditional group that is an immediate child of an at-most-one-of group, if not enabled
@@ -158,8 +154,6 @@ at-most-one-of group for match purposes.
 
 In an at-most-one-of group, at most one immediate child element must be matched.
 
-An empty at-most-one-of group counts as being matched.
-
 \subsection{Package dependency specifications}
 
 A package dependency can be in one of the following base formats. A package manager must warn or
-- 
2.14.1