Fix issue #3805 - wrap macro line with width of one char beyond max

src/macros.rs

@@ -25,6 +25,7 @@ use crate::comment::{
     contains_comment, CharClasses, FindUncommented, FullCodeCharKind, LineClasses,
 };
 use crate::config::lists::*;
+use crate::config::Version;
 use crate::expr::{rewrite_array, rewrite_assign_rhs, RhsAssignKind};
 use crate::lists::{itemize_list, write_list, ListFormatting};
 use crate::overflow;
@@ -1218,8 +1219,16 @@ impl MacroBranch {
             return None;
         }
 
-        // 5 = " => {"
-        let mut result = format_macro_args(context, self.args.clone(), shape.sub_width(5)?)?;
+        let old_body = context.snippet(self.body).trim();
+        let has_block_body = old_body.starts_with('{');
+        let mut prefix_width = 5; // 5 = " => {"
+        if context.config.version() == Version::Two {
+            if has_block_body {
+                prefix_width = 6; // 6 = " => {{"
+            }
+        }
+        let mut result =
+            format_macro_args(context, self.args.clone(), shape.sub_width(prefix_width)?)?;
 
         if multi_branch_style {
             result += " =>";
@@ -1237,9 +1246,7 @@ impl MacroBranch {
         // `$$`). We'll try and format like an AST node, but we'll substitute
         // variables for new names with the same length first.
 
-        let old_body = context.snippet(self.body).trim();
         let (body_str, substs) = replace_names(old_body)?;
-        let has_block_body = old_body.starts_with('{');
 
         let mut config = context.config.clone();
         config.set().hide_parse_errors(true);

tests/source/issue-3805.rs

@@ -0,0 +1,65 @@
+// rustfmt-version: Two
+// rustfmt-format_macro_matchers: true
+
+// From original issue example - Line length 101
+macro_rules! test {
+($aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeio:expr, $add:expr) => {{
+return;
+}};
+}
+
+// Spaces between the `{` and `}`
+macro_rules! test {
+($aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeio:expr, $add:expr) => {     {
+return;
+}      };
+}
+
+// Multi  `{}`
+macro_rules! test {
+($aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeio:expr, $add:expr) => {{{{
+return;
+}}}};
+}
+
+// Multi  `{}` with spaces
+macro_rules! test {
+($aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeio:expr, $add:expr) => {    {    {    {
+return;
+}     }     }    };
+}
+
+// Line length 102
+macro_rules! test {
+($aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeiou:expr, $add:expr) => {{
+return;
+}};
+}
+
+// Line length 103
+macro_rules! test {
+($aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeioua:expr, $add:expr) => {{
+return;
+}};
+}
+
+// With extended macro body - Line length 101
+macro_rules! test {
+($aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeio:expr, $add:expr) => {{
+let VAR = "VALUE"; return VAR;
+}};
+}
+
+// With extended macro body - Line length 102
+macro_rules! test {
+($aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeiou:expr, $add:expr) => {{
+let VAR = "VALUE"; return VAR;
+}};
+}
+
+// With extended macro body - Line length 103
+macro_rules! test {
+($aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeioua:expr, $add:expr) => {{
+let VAR = "VALUE"; return VAR;
+}};
+}

tests/target/issue-3805.rs

@@ -0,0 +1,94 @@
+// rustfmt-version: Two
+// rustfmt-format_macro_matchers: true
+
+// From original issue example - Line length 101
+macro_rules! test {
+    (
+        $aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeio:expr, $add:expr
+    ) => {{
+        return;
+    }};
+}
+
+// Spaces between the `{` and `}`
+macro_rules! test {
+    (
+        $aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeio:expr, $add:expr
+    ) => {{
+        return;
+    }};
+}
+
+// Multi  `{}`
+macro_rules! test {
+    (
+        $aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeio:expr, $add:expr
+    ) => {{
+        {
+            {
+                return;
+            }
+        }
+    }};
+}
+
+// Multi  `{}` with spaces
+macro_rules! test {
+    (
+        $aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeio:expr, $add:expr
+    ) => {{
+        {
+            {
+                return;
+            }
+        }
+    }};
+}
+
+// Line length 102
+macro_rules! test {
+    (
+        $aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeiou:expr, $add:expr
+    ) => {{
+        return;
+    }};
+}
+
+// Line length 103
+macro_rules! test {
+    (
+        $aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeioua:expr, $add:expr
+    ) => {{
+        return;
+    }};
+}
+
+// With extended macro body - Line length 101
+macro_rules! test {
+    (
+        $aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeio:expr, $add:expr
+    ) => {{
+        let VAR = "VALUE";
+        return VAR;
+    }};
+}
+
+// With extended macro body - Line length 102
+macro_rules! test {
+    (
+        $aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeiou:expr, $add:expr
+    ) => {{
+        let VAR = "VALUE";
+        return VAR;
+    }};
+}
+
+// With extended macro body - Line length 103
+macro_rules! test {
+    (
+        $aasdfghj:expr, $qwertyuiop:expr, $zxcvbnmasdfghjkl:expr, $aeiouaeiouaeioua:expr, $add:expr
+    ) => {{
+        let VAR = "VALUE";
+        return VAR;
+    }};
+}