Merge pull request #2309 from FnControlOption/noreturn

Improve type resolution of unlabeled blocks

Author: Techatrix

src/analysis.zig

@@ -2193,10 +2193,17 @@ fn resolveTypeOfNodeUncached(analyser: *Analyser, node_handle: NodeWithHandle) e
             if (std.mem.eql(u8, call_name, "@src")) {
                 return analyser.instanceStdBuiltinType("SourceLocation");
             }
+
             if (std.mem.eql(u8, call_name, "@compileError")) {
                 return .{ .data = .{ .compile_error = node_handle }, .is_type_val = false };
             }
 
+            if (std.mem.eql(u8, call_name, "@panic") or
+                std.mem.eql(u8, call_name, "@trap"))
+            {
+                return Type.fromIP(analyser, .noreturn_type, null);
+            }
+
             if (std.mem.eql(u8, call_name, "@Vector")) {
                 if (params.len != 2) return null;
 
@@ -2414,16 +2421,21 @@ fn resolveTypeOfNodeUncached(analyser: *Analyser, node_handle: NodeWithHandle) e
         .block_two,
         .block_two_semicolon,
         => {
-            const has_zero_statements = switch (tree.nodeTag(node)) {
-                .block_two, .block_two_semicolon => tree.nodeData(node).opt_node_and_opt_node[0] == .none,
-                .block, .block_semicolon => false,
-                else => unreachable,
-            };
-            if (has_zero_statements) {
+            var buffer: [2]Ast.Node.Index = undefined;
+            const statements = tree.blockStatements(&buffer, node).?;
+            if (statements.len == 0) {
                 return Type.fromIP(analyser, .void_type, .void_value);
             }
 
-            const label_token = ast.blockLabel(tree, node) orelse return null;
+            const label_token = ast.blockLabel(tree, node) orelse {
+                const last_statement = statements[statements.len - 1];
+                if (try analyser.resolveTypeOfNodeInternal(.of(last_statement, handle))) |ty| {
+                    if (ty.typeOf(analyser).isNoreturnType()) {
+                        return Type.fromIP(analyser, .noreturn_type, null);
+                    }
+                }
+                return Type.fromIP(analyser, .void_type, .void_value);
+            };
             const block_label = offsets.identifierTokenToNameSlice(tree, label_token);
 
             // TODO: peer type resolution based on all `break` statements
@@ -3381,6 +3393,15 @@ pub const Type = struct {
         };
     }
 
+    pub fn isNoreturnType(self: Type) bool {
+        if (!self.is_type_val) return false;
+        return switch (self.data) {
+            .compile_error => true,
+            .ip_index => |payload| payload.index == .noreturn_type,
+            else => false,
+        };
+    }
+
     pub fn typeDefinitionToken(self: Type) !?TokenWithHandle {
         return switch (self.data) {
             .container => |scope_handle| .{

tests/analysis/block.zig

@@ -0,0 +1,45 @@
+const empty_block = {};
+//    ^^^^^^^^^^^ (void)()
+
+// zig fmt: off
+const void_block = { _ = 1; };
+//    ^^^^^^^^^^ (void)()
+
+const compile_error_block = { @compileError("foo"); };
+//    ^^^^^^^^^^^^^^^^^^^ (noreturn)()
+
+const panic_block = { @panic("foo"); };
+//    ^^^^^^^^^^^ (noreturn)()
+
+const labeled_block_0 = blk: { break :blk @as(i32, 1); };
+//    ^^^^^^^^^^^^^^^ (i32)()
+
+// TODO this should be `i64`
+const labeled_block_1 = blk: {
+//    ^^^^^^^^^^^^^^^ (i32)()
+    if (false) break :blk @as(i32, 1);
+    break :blk @as(i64, 2);
+};
+// zig fmt: on
+
+pub fn main() void {
+    const return_block = {
+        return;
+    };
+    _ = return_block;
+    //  ^^^^^^^^^^^^ (noreturn)()
+
+    for (0..1) |_| {
+        const break_block = {
+            break;
+        };
+        _ = break_block;
+        //  ^^^^^^^^^^^ (noreturn)()
+
+        const continue_block = {
+            continue;
+        };
+        _ = continue_block;
+        //  ^^^^^^^^^^^^^^ (noreturn)()
+    }
+}

tests/analysis/builtins.zig

@@ -111,6 +111,11 @@ const abs_vector_i8 = @abs(@as(@Vector(4, i8), undefined));
 const abs_vector_u8 = @abs(@as(@Vector(4, u8), undefined));
 //    ^^^^^^^^^^^^^ (@Vector(4,u8))()
 
+const panic = @panic("foo");
+//    ^^^^^ (noreturn)()
+const trap = @trap();
+//    ^^^^ (noreturn)()
+
 comptime {
     // Use @compileLog to verify the expected type with the compiler
     // @compileLog(vector_builtin_13);