VariableOrderWrong: Enforce skel.ebuild variable order

Gentoo developers are rejecting routine version bumps for ebuild
variables being defined in a different order than skel.ebuild.
This new lint ensures pkgcheck identifies these problems before
we waste developer time.

Regarding tests, in spite of the massive diff, all that's been done
is re-ordering the variables to avoid introducing new style warnings
into existing tests.

Signed-off-by: Anthony Ryan <anthonyryan1@gmail.com>
Closes: https://github.com/pkgcore/pkgcheck/pull/645
Signed-off-by: Arthur Zamarin <arthurzam@gentoo.org>

1 files changed, 50 insertions, 0 deletions

diff --git a/src/pkgcheck/checks/codingstyle.py b/src/pkgcheck/checks/codingstyle.py
index 67dbe6c1..63704e47 100644
--- a/src/pkgcheck/checks/codingstyle.py
+++ b/src/pkgcheck/checks/codingstyle.py
@@ -1572,3 +1572,53 @@ class SandboxCallCheck(Check):
                 if len(args) != 1 or ":" in pkg.node_str(args[0]):
                     lineno, _ = node.start_point
                     yield InvalidSandboxCall(line=pkg.node_str(node), lineno=lineno + 1, pkg=pkg)
+
+
+class VariableOrderWrong(results.VersionResult, results.Style):
+    """Variable were defined in an unexpected error."""
+
+    def __init__(self, first_var, second_var, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.first_var = first_var
+        self.second_var = second_var
+
+    @property
+    def desc(self):
+        return f"variable {self.first_var} should occur before {self.second_var}"
+
+
+class VariableOrderCheck(Check):
+    """Scan ebuilds for variables defined in a different order than skel.ebuild dictates."""
+
+    _source = sources.EbuildParseRepoSource
+    known_results = frozenset({VariableOrderWrong})
+
+    # Order from skel.ebuild
+    variable_order = (
+        "DESCRIPTION",
+        "HOMEPAGE",
+        "SRC_URI",
+        "S",
+        "LICENSE",
+        "SLOT",
+        "KEYWORDS",
+        "IUSE",
+        "RESTRICT",
+    )
+
+    def feed(self, pkg: bash.ParseTree):
+        var_assigns = []
+
+        for node in pkg.tree.root_node.children:
+            if node.type == "variable_assignment":
+                used_name = pkg.node_str(node.child_by_field_name("name"))
+                if used_name in self.variable_order:
+                    var_assigns.append(used_name)
+
+        index = 0
+        for first_var in var_assigns:
+            if first_var in self.variable_order:
+                new_index = self.variable_order.index(first_var)
+                if new_index < index:
+                    yield VariableOrderWrong(first_var, self.variable_order[index], pkg=pkg)
+                index = new_index