Add initial variable work

.github/copilot-instructions.md

@@ -26,9 +26,8 @@ There will be no `test_buffer.h`. Instead, `test.c` will directly
 Every syntax error path identified in the parser MUST have a corresponding test.
 
 ## Language Syntax
-Since this is a compiler for a new language, do not assume anything
-of its syntax.
-Always check the `specs` directory.
+Since this is a compiler for a new language, do not assume anything of its syntax.
+Always check the `specs` directory to see examples and documentation about the language.
 
 If there is anything unclear, ask the user for clarification.
 It is certainly possible that there are contradictions in the

v0/ast.h

@@ -62,6 +62,26 @@ typedef struct {
     bool is_public;
 } AliasDeclaration;
 
+/**
+ * A declaration of a variable, which may be a constant or not, and may be static or not.
+ */
+typedef struct {
+    /** @brief The name of the variable. */
+    char* name;
+
+    /** @brief The type of the variable. */
+    TypeExpression type;
+
+    /** @brief Whether the variable is public or not. */
+    bool is_public;
+
+    /** @brief Whether the variable is static or not. */
+    bool is_static;
+
+    /** @brief Whether the variable is a constant or not. */
+    bool is_const;
+} VariableDeclaration;
+
 /**
  * The top-level model.
  * Every file matches an entire Module.
@@ -81,6 +101,12 @@ typedef struct {
 
     /** @brief The number of aliases in the module. */
     size_t alias_count;
+
+    /** @brief The list of variables in the module. */
+    VariableDeclaration* variables;
+
+    /** @brief The number of variables in the module. */
+    size_t variable_count;
 } Module;
 
 #endif