+// A version script essentially maps a symbol name to a version tag
+// and an indication of whether symbol is global or local within that
+// version tag. Each symbol maps to at most one version tag.
+// Unfortunately, in practice, version scripts are ambiguous, and list
+// symbols multiple times. Thus, we have to document the matching
+// process.
+
+// This is a description of what the GNU linker does as of 2010-01-11.
+// It walks through the version tags in the order in which they appear
+// in the version script. For each tag, it first walks through the
+// global patterns for that tag, then the local patterns. When
+// looking at a single pattern, it first applies any language specific
+// demangling as specified for the pattern, and then matches the
+// resulting symbol name to the pattern. If it finds an exact match
+// for a literal pattern (a pattern enclosed in quotes or with no
+// wildcard characters), then that is the match that it uses. If
+// finds a match with a wildcard pattern, then it saves it and
+// continues searching. Wildcard patterns that are exactly "*" are
+// saved separately.
+
+// If no exact match with a literal pattern is ever found, then if a
+// wildcard match with a global pattern was found it is used,
+// otherwise if a wildcard match with a local pattern was found it is
+// used.
+
+// This is the result:
+// * If there is an exact match, then we use the first tag in the
+// version script where it matches.
+// + If the exact match in that tag is global, it is used.
+// + Otherwise the exact match in that tag is local, and is used.
+// * Otherwise, if there is any match with a global wildcard pattern:
+// + If there is any match with a wildcard pattern which is not
+// "*", then we use the tag in which the *last* such pattern
+// appears.
+// + Otherwise, we matched "*". If there is no match with a local
+// wildcard pattern which is not "*", then we use the *last*
+// match with a global "*". Otherwise, continue.
+// * Otherwise, if there is any match with a local wildcard pattern:
+// + If there is any match with a wildcard pattern which is not
+// "*", then we use the tag in which the *last* such pattern
+// appears.
+// + Otherwise, we matched "*", and we use the tag in which the
+// *last* such match occurred.
+
+// There is an additional wrinkle. When the GNU linker finds a symbol
+// with a version defined in an object file due to a .symver
+// directive, it looks up that symbol name in that version tag. If it
+// finds it, it matches the symbol name against the patterns for that
+// version. If there is no match with a global pattern, but there is
+// a match with a local pattern, then the GNU linker marks the symbol
+// as local.
+
+// We want gold to be generally compatible, but we also want gold to
+// be fast. These are the rules that gold implements:
+// * If there is an exact match for the mangled name, we use it.
+// + If there is more than one exact match, we give a warning, and
+// we use the first tag in the script which matches.
+// + If a symbol has an exact match as both global and local for
+// the same version tag, we give an error.
+// * Otherwise, we look for an extern C++ or an extern Java exact
+// match. If we find an exact match, we use it.
+// + If there is more than one exact match, we give a warning, and
+// we use the first tag in the script which matches.
+// + If a symbol has an exact match as both global and local for
+// the same version tag, we give an error.
+// * Otherwise, we look through the wildcard patterns, ignoring "*"
+// patterns. We look through the version tags in reverse order.
+// For each version tag, we look through the global patterns and
+// then the local patterns. We use the first match we find (i.e.,
+// the last matching version tag in the file).
+// * Otherwise, we use the "*" pattern if there is one. We give an
+// error if there are multiple "*" patterns.
+
+// At least for now, gold does not look up the version tag for a
+// symbol version found in an object file to see if it should be
+// forced local. There are other ways to force a symbol to be local,
+// and I don't understand why this one is useful.
+
+// Build a set of fast lookup tables for a version script.
+
+void
+Version_script_info::build_lookup_tables()
+{
+ size_t size = this->version_trees_.size();
+ for (size_t j = 0; j < size; ++j)
+ {
+ const Version_tree* v = this->version_trees_[j];
+ this->build_expression_list_lookup(v->local, v, false);
+ this->build_expression_list_lookup(v->global, v, true);
+ }
+}
+
+// If a pattern has backlashes but no unquoted wildcard characters,
+// then we apply backslash unquoting and look for an exact match.
+// Otherwise we treat it as a wildcard pattern. This function returns
+// true for a wildcard pattern. Otherwise, it does backslash
+// unquoting on *PATTERN and returns false. If this returns true,
+// *PATTERN may have been partially unquoted.