Remove support for compact switch statements. (#1191)

I'm still interested in supporting this, but it causes a lot of churn.
That means it really needs to go through the full dart style change
process. Given how many other things are in the air with Dart 3.0, it
seems like now is probably not the ideal time for that.

So, for now, I think we should keep the old formatting where case bodies
always go on their own line.

Author: munificent

CHANGELOG.md

@@ -1,14 +1,21 @@
 # 2.3.0-dev
 
+## New language features
+
 * Format patterns and related features.
+* Format record expressions and record type annotations.
+* Format class modifiers `base`, `final`, `interface`, `mixin`, and `sealed`.
+* Format unnamed libraries.
+
+## Bug fixes and style changes
+
 * Handle `sync*` and `async*` functions with `=>` bodies.
-* Allow switch statements where all case bodies are on the same line as the
-  case when they all fit.
 * Fix bug where parameter metadata wouldn't always split when it should.
 * Don't split after `<` in collection literals.
-* Format record expressions and record type annotations.
-* Format class modifiers `base`, `final`, `interface`, `mixin`, and `sealed`
 * Better indentation of multiline function types inside type argument lists. 
+
+## Internal changes
+
 * Use typed `_visitFunctionOrMethodDeclaration` instead of dynamically typed.
 * Fix metadata test to not fail when record syntax makes whitespace between
   metadata annotation names and `(` significant ([sdk#50769][]).

lib/src/source_visitor.dart

@@ -2792,40 +2792,10 @@ class SourceVisitor extends ThrowingAstVisitor {
     _visitSwitchValue(node.switchKeyword, node.leftParenthesis, node.expression,
         node.rightParenthesis);
     _beginBody(node.leftBracket);
-
-    // If all of the case bodies are small, it looks nice if they go on the same
-    // line as `case`, like:
-    //
-    //   switch (obj) {
-    //     case 1: print('one');
-    //     case 2:
-    //     case 3: print('two or three');
-    //   }
-    //
-    // But it looks bad if some cases are inline and others split:
-    //
-    //   switch (obj) {
-    //     case 1: print('one');
-    //     case 2:
-    //       print('two');
-    //       print('two again');
-    //     case 3: print('two or three');
-    //   }
-    //
-    // So we use a single rule for all cases. If any case splits, because it has
-    // multiple statements, or there is a split in the pattern or body, then
-    // they all split.
-    var caseRule = SplitContainingRule();
-    caseRule.disableSplitOnInnerRules();
-    builder.startLazyRule(caseRule);
-
     for (var member in node.members) {
       _visitLabels(member.labels);
       token(member.keyword);
 
-      // We want a split in the pattern or bodies to force the cases to split.
-      caseRule.enableSplitOnInnerRules();
-
       if (member is SwitchCase) {
         space();
         visit(member.expression);
@@ -2858,24 +2828,16 @@ class SourceVisitor extends ThrowingAstVisitor {
 
       if (member.statements.isNotEmpty) {
         builder.indent();
-        split();
+        newline();
         visitNodes(member.statements, between: oneOrTwoNewlines);
         builder.unindent();
-
-        // We don't want the split between cases to force them to split.
-        caseRule.disableSplitOnInnerRules();
-        oneOrTwoNewlines(preventDivide: true);
+        oneOrTwoNewlines();
       } else {
-        // We don't want the split between cases to force them to split.
-        caseRule.disableSplitOnInnerRules();
-
         // Don't preserve blank lines between empty cases.
-        builder.writeNewline(preventDivide: true);
+        builder.writeNewline();
       }
     }
 
-    builder.endRule();
-
     newline();
     _endBody(node.rightBracket, forceSplit: true);
   }
@@ -4150,9 +4112,8 @@ class SourceVisitor extends ThrowingAstVisitor {
   /// Allow either one or two newlines to be emitted before the next
   /// non-whitespace token based on whether any blank lines exist in the source
   /// between the last token and the next one.
-  void oneOrTwoNewlines({bool preventDivide = false}) {
-    builder.writeNewline(
-        isDouble: _linesBeforeNextToken > 1, preventDivide: preventDivide);
+  void oneOrTwoNewlines() {
+    builder.writeNewline(isDouble: _linesBeforeNextToken > 1);
   }
 
   /// The number of newlines between the last written token and the next one to

test/comments/switch.stmt

@@ -27,7 +27,8 @@ switch (n) {
 
   // comment
 
-  case 1: body;
+  case 1:
+    body;
 
   // comment
 }
@@ -39,9 +40,11 @@ switch (n) {
 }
 <<<
 switch (n) {
-  case 0: zero;
+  case 0:
+    zero;
   // comment
-  case 1: one;
+  case 1:
+    one;
 }
 >>> line comment at end of statement does not force split
 switch (n) {
@@ -51,9 +54,12 @@ switch (n) {
 }
 <<<
 switch (n) {
-  case 0: zero; // comment
-  case 1: one; // comment
-  case 2: two; // comment
+  case 0:
+    zero; // comment
+  case 1:
+    one; // comment
+  case 2:
+    two; // comment
 }
 >>> line comment indentation
 switch (n) {
@@ -66,9 +72,11 @@ switch (n) {
 <<<
 switch (n) {
   // before first
-  case 0: zero;
+  case 0:
+    zero;
   // between
-  case 1: one;
+  case 1:
+    one;
   // after last
 }
 >>> line comment in empty cases
@@ -87,21 +95,6 @@ switch (n) {
   case 2:
   // comment 2
 }
->>> bodies all split or don't together even with comment in the middle
-switch (n) {
-  case 0: longBodyExpression + thatForcesSplit;
-  // comment
-  case 1: c;
-}
-<<<
-switch (n) {
-  case 0:
-    longBodyExpression +
-        thatForcesSplit;
-  // comment
-  case 1:
-    c;
-}
 >>> keeps one blank line around case comments in switch expression
 e = switch (n) {
 

test/regression/1100/1181.stmt

@@ -6,6 +6,7 @@ switch (e) {
 }
 <<<
 switch (e) {
-  case E.e1: break;
+  case E.e1:
+    break;
   case E.e2:
 }