Fix: Compiled disjunctive nested pattern matching no longer crashing (#…

…5574) This PR fixes #5572 I added the corresponding test. <small>By submitting this pull request, I confirm that my contribution is made under the terms of the [MIT license](https://github.com/dafny-lang/dafny/blob/master/LICENSE.txt).</small> --------- Co-authored-by: Remy Willems <[email protected]>
dafny-lang · Jun 26, 2024 · eb2d95b · eb2d95b
1 parent 992cbf8
commit eb2d95b
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Showing 9 changed files with 2,714 additions and 2,764 deletions.
diff --git a/Source/DafnyCore.Test/GeneratedFromDafny/DafnyToRustCompilerCoverage_RASTCoverage.cs b/Source/DafnyCore.Test/GeneratedFromDafny/DafnyToRustCompilerCoverage_RASTCoverage.cs
diff --git a/Source/DafnyCore/AST/Expressions/Conditional/Patterns/IdPattern.cs b/Source/DafnyCore/AST/Expressions/Conditional/Patterns/IdPattern.cs
@@ -22,10 +22,12 @@ public class IdPattern : ExtendedPattern, IHasReferences {
  public DatatypeCtor Ctor;
 
  public bool IsWildcardPattern =>
- Arguments == null && Id.StartsWith("_");
+ Arguments == null && Id.StartsWith(WildcardString);
 
  public bool IsWildcardExact =>
- Arguments == null && Id == "_";
+ Arguments == null && Id == WildcardString;
+
+ public const string WildcardString = "_";
 
  public void MakeAConstructor() {
  this.Arguments = new List<ExtendedPattern>();

diff --git a/Source/DafnyCore/Backends/SinglePassCodeGenerator/SinglePassCodeGenerator.Statement.cs b/Source/DafnyCore/Backends/SinglePassCodeGenerator/SinglePassCodeGenerator.Statement.cs
@@ -594,6 +594,10 @@ public abstract partial class SinglePassCodeGenerator {
  writer = thenWriter;
  } else if (pattern is IdPattern idPattern) {
  if (idPattern.BoundVar != null) {
+ if (idPattern.BoundVar.Tok.val.StartsWith(IdPattern.WildcardString)) {
+ return writer;
+ }
+
  var boundVar = idPattern.BoundVar;
  var valueWriter = DeclareLocalVar(IdName(boundVar), boundVar.Type, idPattern.Tok, writer);
  valueWriter.Write(sourceName);
@@ -651,9 +655,11 @@ public abstract partial class SinglePassCodeGenerator {
  var childPattern = idPattern.Arguments[index];
  if (childPattern is IdPattern { BoundVar: not null } childIdPattern) {
  var boundVar = childIdPattern.BoundVar;
- newSourceName = IdName(boundVar);
- var valueWriter = DeclareLocalVar(newSourceName, boundVar.Type, idPattern.Tok, result);
- valueWriter.Append(destructor);
+ if (!childIdPattern.BoundVar.Name.StartsWith(IdPattern.WildcardString)) {
+ newSourceName = IdName(boundVar);
+ var valueWriter = DeclareLocalVar(newSourceName, boundVar.Type, idPattern.Tok, result);
+ valueWriter.Append(destructor);
+ }
  } else {
  newSourceName = ProtectedFreshId(arg.CompileName);
  var valueWriter = DeclareLocalVar(newSourceName, type, idPattern.Tok, result);

diff --git a/Source/DafnyCore/GeneratedFromDafny/DAST_Format.cs b/Source/DafnyCore/GeneratedFromDafny/DAST_Format.cs
@@ -17,12 +17,12 @@ public static BigInteger SeqToHeight<__T>(Dafny.ISequence<__T> s, Func<__T, BigI
  if ((new BigInteger((s).Count)).Sign == 0) {
  return BigInteger.Zero;
  } else {
- BigInteger _763_i = Dafny.Helpers.Id<Func<__T, BigInteger>>(f)((s).Select(BigInteger.Zero));
- BigInteger _764_j = DAST.Format.__default.SeqToHeight<__T>((s).Drop(BigInteger.One), f);
- if ((_763_i) < (_764_j)) {
- return _764_j;
+ BigInteger _759_i = Dafny.Helpers.Id<Func<__T, BigInteger>>(f)((s).Select(BigInteger.Zero));
+ BigInteger _760_j = DAST.Format.__default.SeqToHeight<__T>((s).Drop(BigInteger.One), f);
+ if ((_759_i) < (_760_j)) {
+ return _760_j;
  } else {
- return _763_i;
+ return _759_i;
  }
  }
  }

diff --git a/Source/DafnyCore/GeneratedFromDafny/DCOMP.cs b/Source/DafnyCore/GeneratedFromDafny/DCOMP.cs
diff --git a/Source/DafnyCore/GeneratedFromDafny/RAST.cs b/Source/DafnyCore/GeneratedFromDafny/RAST.cs
diff --git a/Source/IntegrationTests/TestFiles/LitTests/LitTest/git-issues/git-issue-5572.dfy b/Source/IntegrationTests/TestFiles/LitTests/LitTest/git-issues/git-issue-5572.dfy
@@ -0,0 +1,14 @@
+// RUN: %testDafnyForEachCompiler "%s"
+
+datatype D = A(int) | C(int) {
+ function Test(): D {
+ match this{
+ case A(_) | C(_) =>
+ this
+ }
+ }
+}
+method Main() {
+ var x := C(0).Test();
+ print "ok";
+}
diff --git a/Source/IntegrationTests/TestFiles/LitTests/LitTest/git-issues/git-issue-5572.dfy.expect b/Source/IntegrationTests/TestFiles/LitTests/LitTest/git-issues/git-issue-5572.dfy.expect
@@ -0,0 +1 @@
+ok
diff --git a/docs/dev/news/5572.fix b/docs/dev/news/5572.fix
@@ -0,0 +1 @@
+Compiled disjunctive nested pattern matching no longer crashing