From f13260dd43771bd7e9594cbad942b7d9aa4292fc Mon Sep 17 00:00:00 2001
From: Charles Brunet <charles.brunet@optelgroup.com>
Date: Fri, 25 Aug 2023 09:18:21 -0400
Subject: [PATCH] parser: add ElseNode

---
 mesonbuild/ast/interpreter.py                 |  2 +-
 mesonbuild/ast/visitor.py                     |  4 ++++
 mesonbuild/interpreterbase/interpreterbase.py |  2 +-
 mesonbuild/mparser.py                         | 17 +++++++++++++----
 4 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/mesonbuild/ast/interpreter.py b/mesonbuild/ast/interpreter.py
index 1dea817b1..da2119c89 100644
--- a/mesonbuild/ast/interpreter.py
+++ b/mesonbuild/ast/interpreter.py
@@ -312,7 +312,7 @@ class AstInterpreter(InterpreterBase):
         for i in node.ifs:
             self.evaluate_codeblock(i.block)
         if not isinstance(node.elseblock, EmptyNode):
-            self.evaluate_codeblock(node.elseblock)
+            self.evaluate_codeblock(node.elseblock.block)
 
     def get_variable(self, varname: str) -> int:
         return 0
diff --git a/mesonbuild/ast/visitor.py b/mesonbuild/ast/visitor.py
index 5b1fb6a09..a83782655 100644
--- a/mesonbuild/ast/visitor.py
+++ b/mesonbuild/ast/visitor.py
@@ -143,6 +143,10 @@ class AstVisitor:
         node.condition.accept(self)
         node.block.accept(self)
 
+    def visit_ElseNode(self, node: mparser.IfNode) -> None:
+        self.visit_default_func(node)
+        node.block.accept(self)
+
     def visit_TernaryNode(self, node: mparser.TernaryNode) -> None:
         self.visit_default_func(node)
         node.condition.accept(self)
diff --git a/mesonbuild/interpreterbase/interpreterbase.py b/mesonbuild/interpreterbase/interpreterbase.py
index 7e3f8da5a..5b07dc075 100644
--- a/mesonbuild/interpreterbase/interpreterbase.py
+++ b/mesonbuild/interpreterbase/interpreterbase.py
@@ -303,7 +303,7 @@ class InterpreterBase:
                     mesonlib.project_meson_versions[self.subproject] = prev_meson_version
                 return None
         if not isinstance(node.elseblock, mparser.EmptyNode):
-            self.evaluate_codeblock(node.elseblock)
+            self.evaluate_codeblock(node.elseblock.block)
         return None
 
     def evaluate_testcase(self, node: mparser.TestCaseClauseNode) -> T.Optional[Disabler]:
diff --git a/mesonbuild/mparser.py b/mesonbuild/mparser.py
index ce83cc283..6b578b5af 100644
--- a/mesonbuild/mparser.py
+++ b/mesonbuild/mparser.py
@@ -534,17 +534,25 @@ class IfNode(BaseNode):
         self.condition = condition
         self.block = block
 
+@dataclass(unsafe_hash=True)
+class ElseNode(BaseNode):
+
+    block: CodeBlockNode
+
+    def __init__(self, block: CodeBlockNode):
+        super().__init__(block.lineno, block.colno, block.filename)
+        self.block = block
 
 @dataclass(unsafe_hash=True)
 class IfClauseNode(BaseNode):
 
     ifs: T.List[IfNode] = field(hash=False)
-    elseblock: T.Union[EmptyNode, CodeBlockNode]
+    elseblock: T.Union[EmptyNode, ElseNode]
 
     def __init__(self, linenode: BaseNode):
         super().__init__(linenode.lineno, linenode.colno, linenode.filename)
         self.ifs = []
-        self.elseblock = None
+        self.elseblock = EmptyNode(linenode.lineno, linenode.colno, linenode.filename)
 
 @dataclass(unsafe_hash=True)
 class TestCaseClauseNode(BaseNode):
@@ -919,10 +927,11 @@ class Parser:
             b = self.codeblock()
             clause.ifs.append(IfNode(s, s, b))
 
-    def elseblock(self) -> T.Union[CodeBlockNode, EmptyNode]:
+    def elseblock(self) -> T.Union[ElseNode, EmptyNode]:
         if self.accept('else'):
             self.expect('eol')
-            return self.codeblock()
+            block = self.codeblock()
+            return ElseNode(block)
         return EmptyNode(self.current.lineno, self.current.colno, self.current.filename)
 
     def testcaseblock(self) -> TestCaseClauseNode: