properly handle ASTEntryTag::TagStaticAssertDecl conversion (#1342)

visit children nodes in StaticAssertDecl, so all children exprs will be
inserted in `ast_context.c_exprs`. without visiting it, we will get
panic 'no entry found for key' when translator try to convert
`_Static_assert`.

* Fixes #1332.

Author: kkysen

c2rust-transpile/src/c_ast/conversion.rs

@@ -2360,13 +2360,19 @@ impl ConversionContext {
                 }
 
                 ASTEntryTag::TagStaticAssertDecl if expected_ty & DECL != 0 => {
-                    let assert_expr = CExprId(
-                        node.children[0].expect("StaticAssert must point to an expression"),
-                    );
+                    let assert_expr =
+                        node.children[0].expect("StaticAssert must point to an expression");
+                    let assert_expr = self.visit_expr(assert_expr);
+
                     let message = if node.children.len() > 1 {
-                        Some(CExprId(
-                            node.children[1].expect("Expected static assert message"),
-                        ))
+                        let message = node.children[1].expect("Expected static assert message");
+                        let message = untyped_context
+                            .ast_nodes
+                            .get(&message)
+                            .expect("Expected string literal node");
+                        let message = from_value::<String>(message.extras[2].clone())
+                            .expect("string literal bytes");
+                        Some(message)
                     } else {
                         None
                     };
@@ -2375,6 +2381,7 @@ impl ConversionContext {
                         message,
                     };
                     self.add_decl(new_id, located(node, static_assert));
+                    self.processed_nodes.insert(new_id, OTHER_DECL);
                 }
 
                 t => panic!("Could not translate node {:?} as type {}", t, expected_ty),

c2rust-transpile/src/c_ast/iterators.rs

@@ -184,16 +184,7 @@ fn immediate_decl_children(kind: &CDeclKind) -> Vec<SomeId> {
         Field { typ, .. } => intos![typ.ctype],
         MacroObject { .. } | MacroFunction { .. } => vec![],
         NonCanonicalDecl { canonical_decl } => intos![canonical_decl],
-        StaticAssert {
-            assert_expr,
-            message,
-        } => {
-            if let Some(message) = message {
-                intos![assert_expr, message]
-            } else {
-                intos![assert_expr]
-            }
-        }
+        StaticAssert { assert_expr, .. } => intos![assert_expr],
     }
 }
 

c2rust-transpile/src/c_ast/mod.rs

@@ -1151,7 +1151,7 @@ pub enum CDeclKind {
 
     StaticAssert {
         assert_expr: CExprId,
-        message: Option<CExprId>,
+        message: Option<String>,
     },
 }
 

c2rust-transpile/tests/snapshots/snapshots__transpile@static_assert.c.snap

@@ -0,0 +1,16 @@
+---
+source: c2rust-transpile/tests/snapshots.rs
+expression: cat tests/snapshots/static_assert.rs
+input_file: c2rust-transpile/tests/snapshots/static_assert.c
+---
+#![allow(
+    dead_code,
+    mutable_transmutes,
+    non_camel_case_types,
+    non_snake_case,
+    non_upper_case_globals,
+    unused_assignments,
+    unused_mut
+)]
+#[no_mangle]
+pub unsafe extern "C" fn static_assert() {}

c2rust-transpile/tests/snapshots/static_assert.c

@@ -0,0 +1,4 @@
+void static_assert() {
+    _Static_assert (1);
+    _Static_assert (1, "Expression evaluates to false");
+}