formatter: fix handling of statements ending with ; in if else bl…

…ocks (FuelLabs#3557)

unblocks FuelLabs#3556
closes FuelLabs#3555 

~The situation occurring in the issue seems to happen when the formatter
tries to (incorrectly) assume that an if expression can be in-lined when
there's a newline character inside. During this check, the line kind
(multi-line vs inline) is decided solely depending on the width of the
line, ignoring the existence of a `\n` character.~

~This PR introduces something like a 'catch-all' during the above check
to default to `LineKind::Multiline` if a `\n` is found during the
look-ahead formatting done by the temporary formatter, which forces the
formatter to use multi-line style, so that at the very least we don't
end up with a broken inline format as seen in the issue.~

~This catch-all might unblock the comment formatting PR above as well.~

The above was my misunderstanding - the mistake was further upstream
instead within statement formatting. The inline style was not being
handled for let statements.

swayfmt/src/formatter/mod.rs

@@ -1202,6 +1202,61 @@ pub trait Foo {
 }
 
 fn main() {}
+"#;
+        let mut formatter = Formatter::default();
+        let formatted_sway_code =
+            Formatter::format(&mut formatter, Arc::from(sway_code_to_format), None).unwrap();
+        assert_eq!(correct_sway_code, formatted_sway_code);
+        assert!(test_stability(formatted_sway_code, formatter));
+    }
+
+    #[test]
+    fn test_if_else_multiline_to_inline() {
+        let sway_code_to_format = r#"script;
+
+fn main() {
+    if foo    {
+           let x = 1;
+    } else    {
+        bar(y)   ;
+    }
+}
+"#;
+        let correct_sway_code = r#"script;
+
+fn main() {
+    if foo { let x = 1; } else { bar(y); }
+}
+"#;
+        let mut formatter = Formatter::default();
+        let formatted_sway_code =
+            Formatter::format(&mut formatter, Arc::from(sway_code_to_format), None).unwrap();
+        println!("formatted: {}", formatted_sway_code);
+        assert_eq!(correct_sway_code, formatted_sway_code);
+        assert!(test_stability(formatted_sway_code, formatter));
+    }
+
+    #[test]
+    fn test_if_else_retain_multiline() {
+        let sway_code_to_format = r#"script;
+
+fn main() {
+    if foo    {
+           let really_long_variable = 1;
+    } else    {
+        bar(y)   ;
+    }
+}
+"#;
+        let correct_sway_code = r#"script;
+
+fn main() {
+    if foo {
+        let really_long_variable = 1;
+    } else {
+        bar(y);
+    }
+}
 "#;
         let mut formatter = Formatter::default();
         let formatted_sway_code =

swayfmt/src/utils/language/expr/tests.rs

@@ -155,9 +155,34 @@ other_really_long_var
 0  &&   other_really_long_var    !=    0 {  foo();  }else{bar();}"
 );
 
-fmt_test!(  if_else_control_flow    "if foo { break; } else { continue; }",
+fmt_test!(  if_else_inline_1    "if foo { break; } else { continue; }",
             intermediate_whitespace "if  foo { \n        break; \n}    else  {\n    continue;    \n}");
 
+fmt_test!(  if_else_inline_2
+"if foo { let x = 1; } else { bar(y); }"
+ ,
+
+            intermediate_whitespace 
+"    if foo    {
+        let x = 1;
+    } else    {
+    bar(y)   ;
+}    ");
+
+fmt_test!(  if_else_multiline
+"if foo {
+    let really_long_variable = 1;
+} else {
+    bar(y);
+}",
+
+            intermediate_whitespace 
+"    if foo    {
+    let    really_long_variable = 1;
+    } else    {
+    bar(y)   ;
+}    ");
+
 fmt_test!(  small_if_let "if let Result::Ok(x) = x { 100 } else { 1 }",
             intermediate_whitespace "if    let    Result   ::   Ok( x ) =    x {     100 }   else  {    1 }"
 );

swayfmt/src/utils/language/statement.rs

@@ -67,8 +67,13 @@ impl Format for StatementLet {
         write!(formatted_code, " {} ", self.eq_token.span().as_str())?;
         // expr
         self.expr.format(formatted_code, formatter)?;
-        // `;\n`
-        writeln!(formatted_code, "{}", self.semicolon_token.span().as_str())?;
+        if formatter.shape.code_line.line_style == LineStyle::Inline {
+            // `;`
+            write!(formatted_code, "{}", self.semicolon_token.span().as_str())?;
+        } else {
+            // `;\n`
+            writeln!(formatted_code, "{}", self.semicolon_token.span().as_str())?;
+        }
 
         Ok(())
     }