Update CHANGELOG and test preserve trailing commas on 3.7.

Since the configuration has to be explicitly opted into, it seems worth
supporting it in 3.7 code too.

Author: munificent

CHANGELOG.md

@@ -1,6 +1,32 @@
 ## 3.1.0-wip
 
-* Format null-aware elements.
+### Features
+
+* Allow preserving trailing commas and forcing the surrounding construct to
+  split even when it would otherwise fit on one line. This is off by default
+  (because it breaks [reversibility][] among other reasons) but can be enabled
+  by adding this to a surrounding `analysis_options.yaml` file:
+
+  ```yaml
+  formatter:
+    trailing_commas: preserve
+  ```
+
+  This is similar to how trailing commas work in the old short style formatter
+  applied to code before language version 3.7.
+
+[reversibility]: https://github.com/dart-lang/dart_style/wiki/Reversibility-principle
+
+### Bug fixes
+
+* Don't add a trailing comma in lists that don't allow it, even when there is
+  a trailing comment (#1639).
+
+### Style changes
+
+The following style changes are language versioned and only affect code whose
+language version is 3.8 or later. Dart code at 3.7 or earlier is formatted the
+same as it was before.
 
 * Allow more code on the same line as a named argument or `=>` (#1536, #1545,
   #1668, #1679).
@@ -175,26 +201,6 @@
   );
   ```
 
-* Allow preserving trailing commas and forcing the surrounding construct to
-  split even when it would otherwise fit on one line. This is off by default
-  (because it breaks [reversibility][] among other reasons) but can be enabled
-  by adding this to a surrounding `analysis_options.yaml` file:
-
-  ```yaml
-  formatter:
-    trailing_commas: preserve
-  ```
-
-  This is similar to how trailing commas worked in the old short style
-  formatter.
-
-* Don't add a trailing comma in lists that don't allow it, even when there is
-  a trailing comment (#1639).
-
-* Add tests for digit separators.
-
-[reversibility]: https://github.com/dart-lang/dart_style/wiki/Reversibility-principle
-
 ## 3.0.1
 
 * Handle trailing commas in for-loop updaters (#1354).

lib/src/front_end/piece_factory.dart

@@ -510,30 +510,20 @@ mixin PieceFactory {
         if (forParts.updaters.isNotEmpty) {
           partsList.addCommentsBefore(forParts.updaters.first.beginToken);
 
-          DelimitedListBuilder updaterBuilder;
-          if (isVersion37) {
-            // Create a nested list builder for the updaters so that they can
-            // remain unsplit even while the clauses split.
-            updaterBuilder = DelimitedListBuilder(
-              this,
-              const ListStyle(commas: Commas.nonTrailing),
-            );
-          } else {
-            // Unlike most places in the language, if the updaters split, we
-            // don't want to add a trailing comma. But if the user has preserve
-            // trailing commas on, we should preserve the comma if there is one
-            // but not add one if there isn't and it splits.
-            var style = const ListStyle(commas: Commas.nonTrailing);
-            if (formatter.trailingCommas == TrailingCommas.preserve &&
-                rightParenthesis.hasCommaBefore) {
-              style = const ListStyle(commas: Commas.trailing);
-            }
-
-            // Create a nested list builder for the updaters so that they can
-            // remain unsplit even while the clauses split.
-            updaterBuilder = DelimitedListBuilder(this, style);
+          // Unlike most places in the language, if the updaters split, we
+          // don't want to add a trailing comma. But if the user has preserve
+          // trailing commas on, we should preserve the comma if there is one
+          // but not add one if there isn't and it splits.
+          var style = const ListStyle(commas: Commas.nonTrailing);
+          if (formatter.trailingCommas == TrailingCommas.preserve &&
+              rightParenthesis.hasCommaBefore) {
+            style = const ListStyle(commas: Commas.trailing);
           }
 
+          // Create a nested list builder for the updaters so that they can
+          // remain unsplit even while the clauses split.
+          var updaterBuilder = DelimitedListBuilder(this, style);
+
           forParts.updaters.forEach(updaterBuilder.visit);
 
           // Add the updater builder to the clause builder so that any comments
@@ -1793,7 +1783,6 @@ mixin PieceFactory {
   /// Whether there is a trailing comma at the end of the list delimited by
   /// [rightBracket] which should be preserved.
   bool hasPreservedTrailingComma(Token rightBracket) =>
-      !isVersion37 &&
       formatter.trailingCommas == TrailingCommas.preserve &&
       rightBracket.hasCommaBefore;
 

test/tall/preserve_trailing_commas/collection_for.stmt

@@ -4,7 +4,7 @@
 list = [
   for (x = 1;true;x += 1, x += 2,) e
 ];
-<<< 3.8
+<<<
 list = [
   for (
     x = 1;
@@ -18,7 +18,7 @@ list = [
 list = [
 for (x = 1;true;variable += longValue, another += value) e
 ];
-<<< 3.8
+<<<
 list = [
   for (
     x = 1;

test/tall/preserve_trailing_commas/constructor.unit

@@ -4,7 +4,7 @@
 class A {
   A(int x,);
 }
-<<< 3.8
+<<<
 class A {
   A(
     int x,
@@ -14,15 +14,15 @@ class A {
 class A {
   A(int x, int y);
 }
-<<< 3.8
+<<<
 class A {
   A(int x, int y);
 }
 >>> May still split without trailing comma if doesn't fit.
 class A {
   A(int parameter1, int parameter2, int parameter3);
 }
-<<< 3.8
+<<<
 class A {
   A(
     int parameter1,
@@ -34,7 +34,7 @@ class A {
 class A {
   A(int x, [int y,]);
 }
-<<< 3.8
+<<<
 class A {
   A(
     int x, [
@@ -45,7 +45,7 @@ class A {
 class A {
   A(int x, {int y,});
 }
-<<< 3.8
+<<<
 class A {
   A(
     int x, {
@@ -57,7 +57,7 @@ class A {
   A(int x) : this.named(x,);
   A.named(int x) : this(x,);
 }
-<<< 3.8
+<<<
 class A {
   A(int x)
     : this.named(
@@ -73,7 +73,7 @@ class A {
   A(int x) : this.named(x);
   A.named(int x) : this(x);
 }
-<<< 3.8
+<<<
 class A {
   A(int x) : this.named(x);
   A.named(int x) : this(x);

test/tall/preserve_trailing_commas/enum.unit

@@ -2,17 +2,17 @@
 (trailing_commas preserve)
 >>> Forces split with trailing comma.
 enum E {e,}
-<<< 3.8
+<<<
 enum E {
   e,
 }
 >>> Doesn't force split without trailing comma.
 enum E {e,f,g}
-<<< 3.8
+<<<
 enum E { e, f, g }
 >>> May still split without trailing comma if doesn't fit.
 enum E { value1, value2, value3, value4 }
-<<< 3.8
+<<<
 enum E {
   value1,
   value2,
@@ -21,13 +21,13 @@ enum E {
 }
 >>> Preserve trailing comma but remove semicolon if no members.
 enum E {e,;}
-<<< 3.8
+<<<
 enum E {
   e,
 }
 >>> Remove trailing comma and split if there are members.
 enum E { a, b, c,; int x; }
-<<< 3.8
+<<<
 enum E {
   a,
   b,
@@ -40,7 +40,7 @@ enum Args {
 value(a,b,),
 another(named:1,)
 }
-<<< 3.8
+<<<
 enum Args {
   value(
     a,

test/tall/preserve_trailing_commas/for.stmt

@@ -2,7 +2,7 @@
 (trailing_commas preserve)
 >>> Trailing comma in increments forces them to split.
 for (x = 1;true;x += 1, x += 2,) {stmt;}
-<<< 3.8
+<<<
 for (
   x = 1;
   true;
@@ -13,7 +13,7 @@ for (
 }
 >>> Don't add trailing comma if updaters split.
 for (x = 1;true;variable += longValue, another += value) {stmt;}
-<<< 3.8
+<<<
 for (
   x = 1;
   true;

test/tall/preserve_trailing_commas/function_call.stmt

@@ -2,25 +2,25 @@
 (trailing_commas preserve)
 >>> Forces split with trailing comma.
 function(1,);
-<<< 3.8
+<<<
 function(
   1,
 );
 >>> Doesn't force split without trailing comma.
 function(1,2,3);
-<<< 3.8
+<<<
 function(1, 2, 3);
 >>> May still split without trailing comma if doesn't fit.
 function(argument1, argument2, argument3);
-<<< 3.8
+<<<
 function(
   argument1,
   argument2,
   argument3,
 );
 >>> With named argument.
 function(name: 1,);
-<<< 3.8
+<<<
 function(
   name: 1,
 );

test/tall/preserve_trailing_commas/list_literal.stmt

@@ -2,17 +2,17 @@
 (trailing_commas preserve)
 >>> Forces split with trailing comma.
 [1,];
-<<< 3.8
+<<<
 [
   1,
 ];
 >>> Doesn't force split without trailing comma.
 [1,2,3];
-<<< 3.8
+<<<
 [1, 2, 3];
 >>> May still split without trailing comma if doesn't fit.
 [element1, element2, element3, element4];
-<<< 3.8
+<<<
 [
   element1,
   element2,

test/tall/preserve_trailing_commas/list_pattern.stmt

@@ -2,17 +2,17 @@
 (trailing_commas preserve)
 >>> Forces split with trailing comma.
 var [x,] = list;
-<<< 3.8
+<<<
 var [
   x,
 ] = list;
 >>> Doesn't force split without trailing comma.
 var [x,y,z] = list;
-<<< 3.8
+<<<
 var [x, y, z] = list;
 >>> May still split without trailing comma if doesn't fit.
 var [element1, element2, element3, element4] = list;
-<<< 3.8
+<<<
 var [
   element1,
   element2,

test/tall/preserve_trailing_commas/map_literal.stmt

@@ -2,17 +2,17 @@
 (trailing_commas preserve)
 >>> Forces split with trailing comma.
 map = {a:1,};
-<<< 3.8
+<<<
 map = {
   a: 1,
 };
 >>> Doesn't force split without trailing comma.
 map = {a:1,b:2,c:3};
-<<< 3.8
+<<<
 map = {a: 1, b: 2, c: 3};
 >>> May still split without trailing comma if doesn't fit.
 map = {a: value1, b: value2, c: value3, d: value4};
-<<< 3.8
+<<<
 map = {
   a: value1,
   b: value2,