AST validate unchecked nested blocks (#116)

* AST validate unchecked nested blocks

* Update crates/sema/src/ast_passes.rs

Co-authored-by: DaniPopes <57450786+DaniPopes@users.noreply.github.com>

* Update tests/ui/typeck/unchecked_block.sol

Co-authored-by: DaniPopes <57450786+DaniPopes@users.noreply.github.com>

* Fix

* Fix2

* Fix tests

---------

Co-authored-by: DaniPopes <57450786+DaniPopes@users.noreply.github.com>

crates/sema/src/ast_passes.rs

@@ -24,11 +24,12 @@ struct AstValidator<'sess> {
     span: Span,
     dcx: &'sess DiagCtxt,
     in_loop_depth: u64,
+    in_unchecked_block: bool,
 }
 
 impl<'sess> AstValidator<'sess> {
     fn new(sess: &'sess Session) -> Self {
-        Self { span: Span::DUMMY, dcx: &sess.dcx, in_loop_depth: 0 }
+        Self { span: Span::DUMMY, dcx: &sess.dcx, in_loop_depth: 0, in_unchecked_block: false }
     }
 
     /// Returns the diagnostics context.
@@ -92,19 +93,29 @@ impl<'ast> Visit<'ast> for AstValidator<'_> {
             StmtKind::Break => {
                 if !self.in_loop() {
                     self.dcx()
-                        .err("\"break\" has to be in a \"for\" or \"while\" loop.")
+                        .err("'break' has to be in a 'for' or 'while' loop")
                         .span(stmt.span)
                         .emit();
                 }
             }
             StmtKind::Continue => {
                 if !self.in_loop() {
                     self.dcx()
-                        .err("\"continue\" has to be in a \"for\" or \"while\" loop.")
+                        .err("'continue' has to be in a 'for' or 'while' loop")
                         .span(stmt.span)
                         .emit();
                 }
             }
+            StmtKind::UncheckedBlock(block) => {
+                if self.in_unchecked_block {
+                    self.dcx().err("'unchecked' blocks cannot be nested").span(stmt.span).emit();
+                }
+
+                let prev = self.in_unchecked_block;
+                self.in_unchecked_block = true;
+                self.walk_block(block);
+                self.in_unchecked_block = prev;
+            }
             _ => {}
         }
     }

tests/ui/parser/break_continue_outside_loop.sol

@@ -1,7 +1,7 @@
 contract C {
     function f() {
-        break; //~ ERROR: "break" has to be in a "for" or "while" loop.
-        continue; //~ ERROR: "continue" has to be in a "for" or "while" loop.
+        break; //~ ERROR: 'break' has to be in a 'for' or 'while' loop
+        continue; //~ ERROR: 'continue' has to be in a 'for' or 'while' loop
 
         for (uint256 i = 0; i < 10; i++) {
             break;

tests/ui/parser/break_continue_outside_loop.stderr

@@ -1,11 +1,11 @@
-error: "break" has to be in a "for" or "while" loop.
+error: 'break' has to be in a 'for' or 'while' loop
   --> ROOT/tests/ui/parser/break_continue_outside_loop.sol:LL:CC
    |
 LL |         break;
    |         ^^^^^^
    |
 
-error: "continue" has to be in a "for" or "while" loop.
+error: 'continue' has to be in a 'for' or 'while' loop
   --> ROOT/tests/ui/parser/break_continue_outside_loop.sol:LL:CC
    |
 LL |         continue;

tests/ui/typeck/unchecked_block.sol

@@ -0,0 +1,10 @@
+contract C {
+    function a() public {
+        unchecked {}
+
+        unchecked {
+            unchecked {} //~ ERROR: 'unchecked' blocks cannot be nested
+            unchecked {} //~ ERROR: 'unchecked' blocks cannot be nested
+        }
+    }
+}

tests/ui/typeck/unchecked_block.stderr

@@ -0,0 +1,16 @@
+error: 'unchecked' blocks cannot be nested
+  --> ROOT/tests/ui/typeck/unchecked_block.sol:LL:CC
+   |
+LL |             unchecked {}
+   |             ^^^^^^^^^^^^
+   |
+
+error: 'unchecked' blocks cannot be nested
+  --> ROOT/tests/ui/typeck/unchecked_block.sol:LL:CC
+   |
+LL |             unchecked {}
+   |             ^^^^^^^^^^^^
+   |
+
+error: aborting due to 2 previous errors
+