Fix usage for let else statements. (#8209)

Author: ilyalesokhin-starkware

crates/cairo-lang-semantic/src/usage/mod.rs

@@ -12,7 +12,8 @@ use crate::expr::fmt::ExprFormatter;
 use crate::expr::objects::Arenas;
 use crate::{
     ConcreteStructId, Condition, Expr, ExprFunctionCallArg, ExprId, ExprVarMemberPath,
-    FixedSizeArrayItems, FunctionBody, Parameter, Pattern, PatternId, Statement, VarId,
+    FixedSizeArrayItems, FunctionBody, Parameter, Pattern, PatternId, Statement, StatementLet,
+    VarId,
 };
 
 #[cfg(test)]
@@ -233,9 +234,18 @@ impl Usages {
                 let mut usage = Default::default();
                 for stmt in &expr.statements {
                     match &arenas.statements[*stmt] {
-                        Statement::Let(stmt) => {
-                            self.handle_expr(arenas, stmt.expr, &mut usage);
-                            Self::handle_pattern(&arenas.patterns, stmt.pattern, &mut usage);
+                        Statement::Let(StatementLet {
+                            pattern,
+                            expr,
+                            else_clause,
+                            stable_ptr: _,
+                        }) => {
+                            self.handle_expr(arenas, *expr, &mut usage);
+                            Self::handle_pattern(&arenas.patterns, *pattern, &mut usage);
+
+                            if let Some(else_clause) = else_clause {
+                                self.handle_expr(arenas, *else_clause, &mut usage);
+                            }
                         }
                         Statement::Expr(stmt) => self.handle_expr(arenas, stmt.expr, &mut usage),
                         Statement::Continue(_) => (),

crates/cairo-lang-semantic/src/usage/test_data/usage

@@ -210,3 +210,32 @@ For 4:4:
   Usage: LocalVarId(test::in), LocalVarId(test::counter),
   Changes: LocalVarId(test::in), LocalVarId(test::counter),
   Snapshot_Usage: LocalVarId(test::inner),
+
+//! > ==========================================================================
+
+//! > closure in else block.
+
+//! > test_runner_name
+test_function_usage
+
+//! > function
+fn foo(mut a: Span<u32>, mut b: Span<u32>) -> Option<usize> {
+    let Some(_) = a.pop_front() else {
+        return b.pop_front().map(|q| *q);
+    };
+
+    None
+}
+
+//! > function_name
+foo
+
+//! > module_code
+
+//! > semantic_diagnostics
+
+//! > usage
+Closure 2:33:
+  Usage:
+  Changes:
+  Snapshot_Usage: