Fix DCA handling for __revert intrinsic and std::revert. (#5235)

## Description

This fixes dead code analysis for `__revert` and `std::revert`.

~~We add a new `NodeReturnOptions` return struct to `connect_expression`
which can be used to signal to the parent code block handler that the
expression sibling node should not have its leaves connected.~~

Fixes #5214.

## Checklist

- [x] I have linked to any relevant issues.
- [x] I have commented my code, particularly in hard-to-understand
areas.
- [x] 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: Igor Rončević <[email protected]>

forc-pkg/src/lib.rs

@@ -15,7 +15,3 @@ pub use manifest::{
 };
 #[doc(inline)]
 pub use pkg::*;
-
-const CORE: &str = "core";
-const STD: &str = "std";
-const PRELUDE: &str = "prelude";

forc-pkg/src/manifest.rs

@@ -615,7 +615,7 @@ impl PackageManifest {
     /// Note: If only `core` is specified, we are unable to implicitly add `std` as we cannot
     /// guarantee that the user's `core` is compatible with the implicit `std`.
     fn implicitly_include_std_if_missing(&mut self) {
-        use crate::{CORE, STD};
+        use sway_types::constants::{CORE, STD};
         // Don't include `std` if:
         // - this *is* `core` or `std`.
         // - either `core` or `std` packages are already specified.

forc-pkg/src/pkg.rs

@@ -2,7 +2,6 @@ use crate::{
     lock::Lock,
     manifest::{BuildProfile, Dependency, ManifestFile, MemberManifestFiles, PackageManifestFile},
     source::{self, IPFSNode, Source},
-    CORE, PRELUDE, STD,
 };
 use anyhow::{anyhow, bail, Context, Error, Result};
 use forc_util::{
@@ -46,6 +45,7 @@ use sway_core::{
     BuildTarget, Engines, FinalizedEntry,
 };
 use sway_error::{error::CompileError, handler::Handler, warning::CompileWarning};
+use sway_types::constants::{CORE, PRELUDE, STD};
 use sway_types::{Ident, Span, Spanned};
 use sway_utils::{constants, time_expr, PerformanceData, PerformanceMetric};
 use tracing::{info, warn};

sway-core/src/control_flow_analysis/dead_code_analysis.rs

@@ -12,12 +12,17 @@ use crate::{
 };
 use petgraph::{prelude::NodeIndex, visit::Dfs};
 use std::collections::{BTreeSet, HashMap};
+use sway_ast::Intrinsic;
 use sway_error::{error::CompileError, type_error::TypeError};
 use sway_error::{
     handler::Handler,
     warning::{CompileWarning, Warning},
 };
-use sway_types::{constants::ALLOW_DEAD_CODE_NAME, span::Span, Ident, Named, Spanned};
+use sway_types::{
+    constants::{ALLOW_DEAD_CODE_NAME, STD},
+    span::Span,
+    Ident, Named, Spanned,
+};
 
 impl<'cfg> ControlFlowGraph<'cfg> {
     pub(crate) fn find_dead_code(&self, decl_engine: &DeclEngine) -> Vec<CompileWarning> {
@@ -1263,6 +1268,17 @@ fn connect_expression<'eng: 'cfg, 'cfg>(
             for leaf in current_leaf {
                 graph.add_edge(leaf, fn_exit_point, "".into());
             }
+
+            // check for std::revert and connect to the exit node if that's the case.
+            // we are guaranteed a full call path here since the type checker calls to_fullpath.
+            if let Some(prefix) = fn_decl.call_path.prefixes.first() {
+                if prefix.as_str() == STD && fn_decl.call_path.suffix.as_str() == "revert" {
+                    if let Some(exit_node) = exit_node {
+                        graph.add_edge(fn_exit_point, exit_node, "revert".into());
+                        return Ok(vec![]);
+                    }
+                }
+            }
             // the exit points get connected to an exit node for the application
             if !is_external {
                 if let Some(exit_node) = exit_node {
@@ -1876,6 +1892,12 @@ fn connect_intrinsic_function<'eng: 'cfg, 'cfg>(
         accum.append(&mut res);
         Ok::<_, CompileError>(accum)
     })?;
+    if let Some(exit_node) = exit_node {
+        if kind == &Intrinsic::Revert {
+            graph.add_edge(node, exit_node, "revert".into());
+            result = vec![];
+        }
+    }
     Ok(result)
 }
 

sway-types/src/constants.rs

@@ -64,3 +64,7 @@ pub const VALID_ATTRIBUTE_NAMES: &[&str] = &[
     CFG_ATTRIBUTE_NAME,
     DEPRECATED_ATTRIBUTE_NAME,
 ];
+
+pub const CORE: &str = "core";
+pub const STD: &str = "std";
+pub const PRELUDE: &str = "prelude";

test/src/e2e_vm_tests/test_programs/should_pass/dca/revert/Forc.lock

@@ -0,0 +1,16 @@
+[[package]]
+name = "core"
+source = "path+from-root-32A1D8C54897C96A"
+
+[[package]]
+name = "revert"
+source = "member"
+dependencies = [
+    "core",
+    "std",
+]
+
+[[package]]
+name = "std"
+source = "path+from-root-32A1D8C54897C96A"
+dependencies = ["core"]

test/src/e2e_vm_tests/test_programs/should_pass/dca/revert/Forc.toml

@@ -0,0 +1,10 @@
+[project]
+authors = ["Fuel Labs <[email protected]>"]
+entry = "main.sw"
+license = "Apache-2.0"
+name = "revert"
+implicit-std = false
+
+[dependencies]
+core = { path = "../../../../../../../sway-lib-core" }
+std = { path = "../../../../../../../sway-lib-std" }

test/src/e2e_vm_tests/test_programs/should_pass/dca/revert/src/main.sw

@@ -0,0 +1,43 @@
+script;
+
+fn revert_01() -> u32 {
+    __revert(0);
+
+    422
+}
+
+fn revert_02() -> u32 {
+    __revert(0);
+
+    return 2;
+}
+
+fn revert_03(a: u64) -> u32 {
+    if a > 0 {
+        __revert(0);
+        return 1;
+    }
+    else {
+        return 0;
+    }
+
+    return 3;
+}
+
+fn std_revert_04() -> u32 {
+    revert(0);
+
+    return 4;
+}
+
+
+fn main() -> u32 {
+    let _ = revert_01();
+    let _ = revert_02();
+    let _ = revert_03(0);
+    let _ = std_revert_04();
+    0
+}
+
+
+

test/src/e2e_vm_tests/test_programs/should_pass/dca/revert/test.toml

@@ -0,0 +1,17 @@
+category = "compile"
+expected_warnings = 5
+
+# check: $()422
+# nextln: $()This code is unreachable.
+
+# check: $()return 2;
+# nextln: $()This code is unreachable.
+
+# check: $()return 1;
+# nextln: $()This code is unreachable.
+
+# check: $()return 3;
+# nextln: $()This code is unreachable.
+
+# check: $()return 4;
+# nextln: $()This code is unreachable.