Fixes DCA unused struct warning. (FuelLabs#4238)

## Description The issue was that a struct that is used as an accessed field of a public struct results in unused struct warning. The solution was to add to the DCA graph an edge from the access fields to the parent struct. DCA graph before fix: ![3683_before](https://user-images.githubusercontent.com/1188095/223726504-2dc36d96-adf6-464f-b413-af4e7c928647.png) DCA graph after fix: ![3683_after](https://user-images.githubusercontent.com/1188095/223726534-326e29f6-a590-427c-9c1a-f6175891e6c1.png) Closes FuelLabs#3683 ## Checklist - [x] I have linked to any relevant issues. - [x] I have commented my code, particularly in hard-to-understand areas. - [ ] I have updated the documentation where relevant (API docs, the reference, and the Sway book). - [x] I have added tests that prove my fix is effective or that my feature works. - [x] I have added (or requested a maintainer to add) the necessary `Breaking*` or `New Feature` labels where relevant. - [x] I have done my best to ensure that my PR adheres to [the Fuel Labs Code Review Standards](https://github.com/FuelLabs/rfcs/blob/master/text/code-standards/external-contributors.md). - [x] I have requested a review from the relevant team or maintainers. Co-authored-by: João Matos <[email protected]>
taaraneh · Mar 8, 2023 · 0cafc16 · 0cafc16
1 parent 0dcae3d
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diff --git a/sway-core/src/control_flow_analysis/dead_code_analysis.rs b/sway-core/src/control_flow_analysis/dead_code_analysis.rs
@@ -1219,6 +1219,14 @@ fn connect_expression<'eng: 'cfg, 'cfg>(
                 graph.add_edge(*leaf, this_ix, "".into());
             }
             graph.add_edge(this_ix, field_ix, "".into());
+
+            if let Some(struct_node_ix) = graph
+                .namespace
+                .find_struct_decl(resolved_type_of_parent.suffix.as_str())
+            {
+                graph.add_edge(this_ix, *struct_node_ix, "".into());
+            }
+
             Ok(vec![this_ix])
         }
         AsmExpression { registers, .. } => {

diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/dca/struct_field_no_warning/Forc.lock b/test/src/e2e_vm_tests/test_programs/should_pass/dca/struct_field_no_warning/Forc.lock
@@ -0,0 +1,3 @@
+[[package]]
+name = 'struct_field_no_warning'
+source = 'member'
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/dca/struct_field_no_warning/Forc.toml b/test/src/e2e_vm_tests/test_programs/should_pass/dca/struct_field_no_warning/Forc.toml
@@ -0,0 +1,6 @@
+[project]
+authors = ["Fuel Labs <[email protected]>"]
+entry = "main.sw"
+implicit-std = false
+license = "Apache-2.0"
+name = "struct_field_no_warning"
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/dca/struct_field_no_warning/src/main.sw b/test/src/e2e_vm_tests/test_programs/should_pass/dca/struct_field_no_warning/src/main.sw
@@ -0,0 +1,13 @@
+script;
+
+struct CallData {
+  id: u64,
+}
+
+pub struct Proposal {
+  call_data: CallData,
+}
+
+fn main(p: Proposal) -> u64 {
+  p.call_data.id
+}
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/dca/struct_field_no_warning/test.toml b/test/src/e2e_vm_tests/test_programs/should_pass/dca/struct_field_no_warning/test.toml
@@ -0,0 +1 @@
+category = "compile"