Revert changes to while loop handling in analyze_return_paths (FuelLa…

…bs#3433)

Revert changes to while loop handling in `analyze_return_paths`.

sway-core/src/control_flow_analysis/analyze_return_paths.rs

@@ -20,7 +20,7 @@ impl ControlFlowGraph {
         // do a depth first traversal and cover individual inner ast nodes
         let mut leaves = vec![];
         for ast_entrypoint in module_nodes {
-            let l_leaves = connect_node(type_engine, ast_entrypoint, &mut graph, &leaves)?.0;
+            let l_leaves = connect_node(type_engine, ast_entrypoint, &mut graph, &leaves)?;
             if let NodeConnection::NextStep(nodes) = l_leaves {
                 leaves = nodes;
             }
@@ -126,7 +126,7 @@ fn connect_node(
     node: &ty::TyAstNode,
     graph: &mut ControlFlowGraph,
     leaves: &[NodeIndex],
-) -> Result<(NodeConnection, ReturnStatementNodes), CompileError> {
+) -> Result<NodeConnection, CompileError> {
     let span = node.span.clone();
     match &node.content {
         ty::TyAstNodeContent::Expression(ty::TyExpression {
@@ -138,46 +138,20 @@ fn connect_node(
             for leaf_ix in leaves {
                 graph.add_edge(*leaf_ix, this_index, "".into());
             }
-            Ok((NodeConnection::Return(this_index), vec![]))
+            Ok(NodeConnection::Return(this_index))
         }
         ty::TyAstNodeContent::Expression(ty::TyExpression {
-            expression: ty::TyExpressionVariant::WhileLoop { body, .. },
+            expression: ty::TyExpressionVariant::WhileLoop { .. },
             ..
         }) => {
-            // This is very similar to the dead code analysis for a while loop.
-            let entry = graph.add_node(node.into());
-            let while_loop_exit = graph.add_node("while loop exit".to_string().into());
-            for leaf in leaves {
-                graph.add_edge(*leaf, entry, "".into());
-            }
-            // it is possible for a whole while loop to be skipped so add edge from
-            // beginning of while loop straight to exit
-            graph.add_edge(
-                entry,
-                while_loop_exit,
-                "condition is initially false".into(),
-            );
-            let mut leaves = vec![entry];
-
-            // We need to dig into the body of the while loop in case there is a break or a
-            // continue at some level.
-            let (l_leaves, inner_returns) =
-                depth_first_insertion_code_block(type_engine, body, graph, &leaves)?;
-
-            // insert edges from end of block back to beginning of it
-            for leaf in &l_leaves {
-                graph.add_edge(*leaf, entry, "loop repeats".into());
-            }
-
-            leaves = l_leaves;
+            // An abridged version of the dead code analysis for a while loop
+            // since we don't really care about what the loop body contains when detecting
+            // divergent paths
+            let node = graph.add_node(node.into());
             for leaf in leaves {
-                graph.add_edge(leaf, while_loop_exit, "".into());
+                graph.add_edge(*leaf, node, "while loop entry".into());
             }
-
-            Ok((
-                NodeConnection::NextStep(vec![while_loop_exit]),
-                inner_returns,
-            ))
+            Ok(NodeConnection::NextStep(vec![node]))
         }
         ty::TyAstNodeContent::Expression(ty::TyExpression { .. }) => {
             let entry = graph.add_node(node.into());
@@ -186,19 +160,11 @@ fn connect_node(
             for leaf in leaves {
                 graph.add_edge(*leaf, entry, "".into());
             }
-            Ok((NodeConnection::NextStep(vec![entry]), vec![]))
+            Ok(NodeConnection::NextStep(vec![entry]))
         }
-        ty::TyAstNodeContent::SideEffect => Ok((NodeConnection::NextStep(leaves.to_vec()), vec![])),
-        ty::TyAstNodeContent::Declaration(decl) => Ok((
-            NodeConnection::NextStep(connect_declaration(
-                type_engine,
-                node,
-                decl,
-                graph,
-                span,
-                leaves,
-            )?),
-            vec![],
+        ty::TyAstNodeContent::SideEffect => Ok(NodeConnection::NextStep(leaves.to_vec())),
+        ty::TyAstNodeContent::Declaration(decl) => Ok(NodeConnection::NextStep(
+            connect_declaration(type_engine, node, decl, graph, span, leaves)?,
         )),
     }
 }
@@ -318,7 +284,7 @@ fn connect_typed_fn_decl(
 ) -> Result<(), CompileError> {
     let fn_exit_node = graph.add_node(format!("\"{}\" fn exit", fn_decl.name.as_str()).into());
     let return_nodes =
-        depth_first_insertion_code_block(type_engine, &fn_decl.body, graph, &[entry_node])?.0;
+        depth_first_insertion_code_block(type_engine, &fn_decl.body, graph, &[entry_node])?;
     for node in return_nodes {
         graph.add_edge(node, fn_exit_node, "return".into());
     }
@@ -343,18 +309,17 @@ fn depth_first_insertion_code_block(
     node_content: &ty::TyCodeBlock,
     graph: &mut ControlFlowGraph,
     leaves: &[NodeIndex],
-) -> Result<(ReturnStatementNodes, Vec<NodeIndex>), CompileError> {
+) -> Result<ReturnStatementNodes, CompileError> {
     let mut leaves = leaves.to_vec();
     let mut return_nodes = vec![];
     for node in node_content.contents.iter() {
-        let (this_node, inner_returns) = connect_node(type_engine, node, graph, &leaves)?;
+        let this_node = connect_node(type_engine, node, graph, &leaves)?;
         match this_node {
             NodeConnection::NextStep(nodes) => leaves = nodes,
             NodeConnection::Return(node) => {
                 return_nodes.push(node);
             }
         }
-        return_nodes.extend(inner_returns);
     }
-    Ok((return_nodes, leaves))
+    Ok(return_nodes)
 }

test/src/e2e_vm_tests/test_programs/should_fail/while_explicit_ret_1/Forc.lock

@@ -0,0 +1,3 @@
+[[package]]
+name = 'while_explicit_ret_1'
+source = 'member'

test/src/e2e_vm_tests/test_programs/should_fail/while_explicit_ret_1/Forc.toml

@@ -0,0 +1,6 @@
+[project]
+authors = ["Fuel Labs <[email protected]>"]
+entry = "main.sw"
+implicit-std = false
+license = "Apache-2.0"
+name = "while_explicit_ret_1"

test/src/e2e_vm_tests/test_programs/should_fail/while_explicit_ret_1/src/main.sw

@@ -0,0 +1,7 @@
+script;
+
+fn main() -> u64 {
+    while true {
+        return 0;
+    };
+}

test/src/e2e_vm_tests/test_programs/should_fail/while_explicit_ret_1/test.toml

@@ -0,0 +1,3 @@
+category = "fail"
+
+# check: $()This path must return a value of type "u64" from function "main", but it does not.

test/src/e2e_vm_tests/test_programs/should_fail/while_explicit_ret_2/Forc.lock

@@ -0,0 +1,3 @@
+[[package]]
+name = 'while_explicit_ret_2'
+source = 'member'

test/src/e2e_vm_tests/test_programs/should_fail/while_explicit_ret_2/Forc.toml

@@ -0,0 +1,6 @@
+[project]
+authors = ["Fuel Labs <[email protected]>"]
+entry = "main.sw"
+implicit-std = false
+license = "Apache-2.0"
+name = "while_explicit_ret_2"

test/src/e2e_vm_tests/test_programs/should_fail/while_explicit_ret_2/src/main.sw

@@ -0,0 +1,8 @@
+script;
+
+fn main() -> u64 {
+    while true {
+        if true {        }
+        return 0;
+    };
+}

test/src/e2e_vm_tests/test_programs/should_fail/while_explicit_ret_2/test.toml

@@ -0,0 +1,3 @@
+category = "fail"
+
+# check: $()This path must return a value of type "u64" from function "main", but it does not.