Don't add semicolons unnecessarily for non-ambiguous statements (#980)

* Add tests

* Check before adding semicolons

* Update snapshots

* Update changelog

Author: JohnnyMorganz

CHANGELOG.md

@@ -23,6 +23,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Luau: fixed parentheses incorrectly removed in `(expr :: assertion) < foo` when multilining the expression, leading to a syntax error ([#940](https://github.com/JohnnyMorganz/StyLua/issues/940))
 - Fixed panic when attempting to format a file outside of the current working directory when `--respect-ignores` is enabled ([#969](https://github.com/JohnnyMorganz/StyLua/pull/969))
+- Fixed unnecessary semicolons being introduced at the end of statements when incorrectly determined as ambiguous ([#963](https://github.com/JohnnyMorganz/StyLua/issues/963))
 
 ## [2.0.2] - 2024-12-07
 

src/formatters/block.rs

@@ -473,18 +473,46 @@ fn var_has_parentheses(var: &Var) -> bool {
     }
 }
 
+fn expression_ends_with_identifier_or_parentheses(expression: &Expression) -> bool {
+    match expression {
+        Expression::Parentheses { .. } => true,
+        Expression::FunctionCall(_) => true,
+        Expression::Var(_) => true,
+        Expression::BinaryOperator { rhs, .. } => {
+            expression_ends_with_identifier_or_parentheses(rhs)
+        }
+        Expression::UnaryOperator { expression, .. } => {
+            expression_ends_with_identifier_or_parentheses(expression)
+        }
+        _ => false,
+    }
+}
+
+// Ambiguous syntax can only occur if the current statement ends with an identifier, function call, or parentheses
+fn stmt_ends_with_identifier_or_parentheses(stmt: &Stmt) -> bool {
+    match stmt {
+        Stmt::Assignment(assignment) => match assignment.expressions().last() {
+            Some(pair) => expression_ends_with_identifier_or_parentheses(pair.value()),
+            None => false,
+        },
+        Stmt::LocalAssignment(local_assignment) => match local_assignment.expressions().last() {
+            Some(pair) => expression_ends_with_identifier_or_parentheses(pair.value()),
+            None => false,
+        },
+        Stmt::FunctionCall(_) => true,
+        Stmt::Repeat(repeat) => expression_ends_with_identifier_or_parentheses(repeat.until()),
+        _ => false,
+    }
+}
+
 fn check_stmt_requires_semicolon(
     stmt: &Stmt,
     next_stmt: Option<&&(Stmt, Option<TokenReference>)>,
 ) -> bool {
     // Need to check next statement if it is a function call, with a parameters expression as the prefix
     // If so, removing a semicolon may lead to ambiguous syntax
-    // Ambiguous syntax can only occur if the current statement is a (Local)Assignment, FunctionCall or a Repeat block
-    match stmt {
-        Stmt::Assignment(_)
-        | Stmt::LocalAssignment(_)
-        | Stmt::FunctionCall(_)
-        | Stmt::Repeat(_) => match next_stmt {
+    stmt_ends_with_identifier_or_parentheses(stmt)
+        && match next_stmt {
             Some((Stmt::FunctionCall(function_call), _)) => match function_call.prefix() {
                 Prefix::Expression(expression) => {
                     matches!(&**expression, Expression::Parentheses { .. })
@@ -500,9 +528,7 @@ fn check_stmt_requires_semicolon(
                 var_has_parentheses(compound_assignment.lhs())
             }
             _ => false,
-        },
-        _ => false,
-    }
+        }
 }
 
 /// Formats a block node. Note: the given shape to the block formatter should already be at the correct indentation level

tests/inputs/ambiguous-syntax-2.lua

@@ -0,0 +1,20 @@
+-- https://github.com/JohnnyMorganz/StyLua/issues/963
+local value = nil
+
+(Foo):Call()
+
+local tbl = {}
+
+(Foo):Call()
+
+local x = 1
+
+(Foo):Call()
+
+local x = "value"
+
+(Foo):Call()
+
+local x = function() end
+
+(Foo):Call()

tests/inputs/ambiguous-syntax-3.lua

@@ -0,0 +1,17 @@
+local x = call "";
+(foo or bar and baz)(bar)
+
+local x = call {};
+(foo or bar and baz)(bar)
+
+local x = identifier;
+(foo or bar and baz)(bar)
+
+local x = (identifier);
+(foo or bar and baz)(bar)
+
+local x = x.y;
+(foo or bar and baz)(bar)
+
+local x = x["y"];
+(foo or bar and baz)(bar)

tests/snapshots/[email protected]

@@ -0,0 +1,26 @@
+---
+source: tests/tests.rs
+expression: "format(&contents, LuaVersion::Lua51)"
+input_file: tests/inputs/ambiguous-syntax-2.lua
+snapshot_kind: text
+---
+-- https://github.com/JohnnyMorganz/StyLua/issues/963
+local value = nil
+
+(Foo):Call()
+
+local tbl = {}
+
+(Foo):Call()
+
+local x = 1
+
+(Foo):Call()
+
+local x = "value"
+
+(Foo):Call()
+
+local x = function() end
+
+(Foo):Call()

tests/snapshots/[email protected]

@@ -0,0 +1,23 @@
+---
+source: tests/tests.rs
+expression: "format(&contents, LuaVersion::Lua51)"
+input_file: tests/inputs/ambiguous-syntax-3.lua
+snapshot_kind: text
+---
+local x = call("");
+(foo or bar and baz)(bar)
+
+local x = call({});
+(foo or bar and baz)(bar)
+
+local x = identifier;
+(foo or bar and baz)(bar)
+
+local x = identifier;
+(foo or bar and baz)(bar)
+
+local x = x.y;
+(foo or bar and baz)(bar)
+
+local x = x["y"];
+(foo or bar and baz)(bar)

tests/snapshots/[email protected]

@@ -1,6 +1,8 @@
 ---
 source: tests/tests.rs
-expression: format(&contents)
+expression: "format(&contents, LuaVersion::Lua51)"
+input_file: tests/inputs/excess-parentheses.lua
+snapshot_kind: text
 ---
 local x
 something(x)
@@ -11,7 +13,7 @@ local z = (...) == nil and foo or bar
 local foo = not (bar and baz)
 local bar = #bar and baz
 local cond = condition and (not object or object.Value == y)
-local baz = (-4 + 3) * 2;
+local baz = (-4 + 3) * 2
 
 ({}):foo();
 ("hello"):format()
@@ -34,4 +36,3 @@ local y = "hello"
 local z = function()
 	return true
 end
-