transpile: Avoid unnecessary parentheses around calls or fields

Author: Rua

c2rust-ast-builder/src/builder.rs

@@ -2222,19 +2222,21 @@ fn parenthesize_if_necessary(mut outer: Expr) -> Expr {
         }
     };
     match outer {
+        Expr::MethodCall(ref mut emc) => {
+            // Do not parenthesize `a.b.c()` or `a().b()` or `a[b].c()`
+            if !matches!(
+                *emc.receiver,
+                Expr::Field(..) | Expr::Call(..) | Expr::Index(..)
+            ) {
+                parenthesize_if_gt(&mut emc.receiver);
+            }
+        }
         Expr::Field(ref mut ef) => {
-            if let Expr::Index(_) = *ef.base {
-                /* we do not need to parenthesize the indexing in a[b].c */
-            } else {
-                /*if let Expr::Unary(_) = *ef.base {
-                    parenthesize_mut(&mut ef.base);
-                } else { */
+            // Do not parenthesize `a().b` or `a[b].c`
+            if !matches!(*ef.base, Expr::Call(..) | Expr::Index(..)) {
                 parenthesize_if_gt(&mut ef.base);
             }
         }
-        Expr::MethodCall(ref mut emc) => {
-            parenthesize_if_gt(&mut emc.receiver);
-        }
         Expr::Call(ref mut ec) => {
             parenthesize_if_gt(&mut ec.func);
         }

c2rust-transpile/tests/snapshots/snapshots__transpile-aarch64@vm_x86.c.snap

@@ -51,7 +51,7 @@ pub unsafe extern "C" fn VM_CallCompiled(
         as *mut ::core::ffi::c_int) = 0 as ::core::ffi::c_int;
     *(&mut *image.offset(programStack as isize) as *mut byte as *mut ::core::ffi::c_int) =
         -(1 as ::core::ffi::c_int);
-    entryPoint = ((*vm).codeBase).offset((*vm).entryOfs as isize);
+    entryPoint = (*vm).codeBase.offset((*vm).entryOfs as isize);
     opStack =
         (stack.as_mut_ptr() as *mut ::core::ffi::c_int).offset(16 as ::core::ffi::c_int as isize);
     *opStack = 0 as ::core::ffi::c_int;

c2rust-transpile/tests/snapshots/snapshots__transpile-x86_64@vm_x86.c.snap

@@ -53,7 +53,7 @@ pub unsafe extern "C" fn VM_CallCompiled(
         as *mut ::core::ffi::c_int) = 0 as ::core::ffi::c_int;
     *(&mut *image.offset(programStack as isize) as *mut byte as *mut ::core::ffi::c_int) =
         -(1 as ::core::ffi::c_int);
-    entryPoint = ((*vm).codeBase).offset((*vm).entryOfs as isize);
+    entryPoint = (*vm).codeBase.offset((*vm).entryOfs as isize);
     opStack =
         (stack.as_mut_ptr() as *mut ::core::ffi::c_int).offset(16 as ::core::ffi::c_int as isize);
     *opStack = 0 as ::core::ffi::c_int;

c2rust-transpile/tests/snapshots/[email protected]

@@ -48,10 +48,10 @@ pub unsafe extern "C" fn unary_with_side_effect() {
         unsafe extern "C" fn() -> ::core::ffi::c_int,
     >(side_effect)() as isize) as *const ::core::ffi::c_char;
     *arr[side_effect() as usize];
-    arr[side_effect() as usize] = (arr[side_effect() as usize]).offset(1);
-    arr[side_effect() as usize] = (arr[side_effect() as usize]).offset(-1);
-    arr[side_effect() as usize] = (arr[side_effect() as usize]).offset(1);
-    arr[side_effect() as usize] = (arr[side_effect() as usize]).offset(-1);
+    arr[side_effect() as usize] = arr[side_effect() as usize].offset(1);
+    arr[side_effect() as usize] = arr[side_effect() as usize].offset(-1);
+    arr[side_effect() as usize] = arr[side_effect() as usize].offset(1);
+    arr[side_effect() as usize] = arr[side_effect() as usize].offset(-1);
 }
 #[no_mangle]
 pub unsafe extern "C" fn compound_literal() {