diff --git a/engine/runtime/src/main/java/org/enso/compiler/TreeToIr.java b/engine/runtime/src/main/java/org/enso/compiler/TreeToIr.java
index 0b1083ddc3c..2a7b1f4bee3 100644
--- a/engine/runtime/src/main/java/org/enso/compiler/TreeToIr.java
+++ b/engine/runtime/src/main/java/org/enso/compiler/TreeToIr.java
@@ -13,11 +13,11 @@ import org.enso.compiler.core.IR$Case$Expr;
 import org.enso.compiler.core.IR$Comment$Documentation;
 import org.enso.compiler.core.IR$DefinitionArgument$Specified;
 import org.enso.compiler.core.IR$Error$Syntax;
-import org.enso.compiler.core.IR$Error$Syntax$InvalidBaseInDecimalLiteral$;
 import org.enso.compiler.core.IR$Error$Syntax$InvalidForeignDefinition;
 import org.enso.compiler.core.IR$Error$Syntax$UnexpectedDeclarationInType$;
 import org.enso.compiler.core.IR$Error$Syntax$UnexpectedExpression$;
-import org.enso.compiler.core.IR$Error$Syntax$UnsupportedSyntax;
+import org.enso.compiler.core.IR$Error$Syntax$EmptyParentheses$;
+import org.enso.compiler.core.IR$Error$Syntax$UnrecognizedToken$;
 import org.enso.compiler.core.IR$Expression$Binding;
 import org.enso.compiler.core.IR$Expression$Block;
 import org.enso.compiler.core.IR$Foreign$Definition;
@@ -58,16 +58,13 @@ import org.enso.syntax.text.Location;
 import org.enso.syntax2.ArgumentDefinition;
 import org.enso.syntax2.Base;
 import org.enso.syntax2.DocComment;
-import org.enso.syntax2.Either;
-import org.enso.syntax2.FractionalDigits;
 import org.enso.syntax2.Line;
-import org.enso.syntax2.MultipleOperatorError;
 import org.enso.syntax2.TextElement;
 import org.enso.syntax2.Token;
-import org.enso.syntax2.Token.Operator;
 import org.enso.syntax2.Tree;
 
 import scala.Option;
+import scala.collection.immutable.LinearSeq;
 import scala.collection.immutable.List;
 import scala.jdk.javaapi.CollectionConverters;
 
@@ -162,11 +159,14 @@ final class TreeToIr {
         var args = translateArgumentsDefinition(fn.getArgs());
         var body = translateExpression(fn.getBody());
 
+        if (body == null) {
+            throw new NullPointerException();
+        }
         var binding = new IR$Module$Scope$Definition$Method$Binding(
           methodRef,
           args,
           body,
-          getIdentifiedLocation(inputAst),
+          getIdentifiedLocation(inputAst, 0, 1),
           meta(), diag()
         );
         yield cons(binding, appendTo);
@@ -200,15 +200,21 @@ final class TreeToIr {
       }
       case Tree.Assignment a -> {
         var reference = translateMethodReference(a.getPattern(), false);
+        var body = translateExpression(a.getExpr());
+        if (body == null) {
+            throw new NullPointerException();
+        }
+        var aLoc = expandToContain(getIdentifiedLocation(a.getExpr()), body.location());
         var binding = new IR$Module$Scope$Definition$Method$Binding(
           reference,
           nil(),
-          translateExpression(a.getExpr()),
-          getIdentifiedLocation(a),
+          body.setLocation(aLoc),
+          expandToContain(getIdentifiedLocation(a), aLoc),
           meta(), diag()
         );
         yield cons(binding, appendTo);
       }
+
       case Tree.TypeSignature sig -> {
         var methodReference = translateMethodReference(sig.getVariable(), true);
         var signature = translateType(sig.getType(), false);
@@ -405,9 +411,10 @@ final class TreeToIr {
     );
   }
 
-  private IR.Expression translateCall(Tree tree) {
+  private IR.Expression translateCall(Tree ast) {
     var args = new java.util.ArrayList<IR.CallArgument>();
     var hasDefaultsSuspended = false;
+    var tree = ast;
     for (;;) {
       switch (tree) {
         case Tree.App app when app.getArg() instanceof Tree.AutoScope -> {
@@ -458,7 +465,7 @@ final class TreeToIr {
           return new IR$Application$Prefix(
                   func, argsList,
                   hasDefaultsSuspended,
-                  getIdentifiedLocation(tree),
+                  getIdentifiedLocation(ast),
                   meta(),
                   diag()
           );
@@ -467,6 +474,33 @@ final class TreeToIr {
     }
   }
 
+  private IR.Name translateOldStyleLambdaArgumentName(Tree arg, boolean[] suspended, IR.Expression[] defaultValue) {
+    return switch (arg) {
+      case Tree.Group g -> translateOldStyleLambdaArgumentName(g.getBody(), suspended, defaultValue);
+      case Tree.Wildcard wild -> new IR$Name$Blank(getIdentifiedLocation(wild.getToken()), meta(), diag());
+      case Tree.OprApp app when "=".equals(app.getOpr().getRight().codeRepr()) -> {
+          if (defaultValue != null) {
+            defaultValue[0] = translateExpression(app.getRhs(), false);
+          }
+          yield translateOldStyleLambdaArgumentName(app.getLhs(), suspended, null);
+      }
+      case Tree.Ident id -> {
+        IR.Expression identifier = translateIdent(id, false);
+        yield switch (identifier) {
+          case IR.Name name_ -> name_;
+          default -> throw new UnhandledEntity(identifier, "translateOldStyleLambdaArgumentName");
+        };
+      }
+      case Tree.UnaryOprApp app when "~".equals(app.getOpr().codeRepr()) -> {
+          if (suspended != null) {
+            suspended[0] = true;
+          }
+          yield translateOldStyleLambdaArgumentName(app.getRhs(), null, defaultValue);
+      }
+      default -> throw new UnhandledEntity(arg, "translateOldStyleLambdaArgumentName");
+    };
+  }
+
   /** Translates an arbitrary program expression from {@link Tree} into {@link IR}.
    *
    * @param tree the expression to be translated
@@ -486,6 +520,18 @@ final class TreeToIr {
     return switch (tree) {
       case Tree.OprApp app -> {
         var op = app.getOpr().getRight();
+        if (op == null) {
+          var at = getIdentifiedLocation(app);
+          var arr = app.getOpr().getLeft().getOperators();
+          if (arr.size() > 0 && arr.get(0).codeRepr().equals("=")) {
+              var errLoc = arr.size() > 1 ? getIdentifiedLocation(arr.get(1)) : at;
+              var err = new IR$Error$Syntax(errLoc.get(), IR$Error$Syntax$UnrecognizedToken$.MODULE$, meta(), diag());
+              var name = buildName(app.getLhs());
+              yield new IR$Expression$Binding(name, err, at, meta(), diag());
+          } else {
+              yield new IR$Error$Syntax(at.get(), IR$Error$Syntax$UnrecognizedToken$.MODULE$, meta(), diag());
+          }
+        }
         yield switch (op.codeRepr()) {
           case "." -> {
             final Option<IdentifiedLocation> loc = getIdentifiedLocation(tree);
@@ -495,27 +541,18 @@ final class TreeToIr {
           case "->" -> {
             // Old-style lambdas; this syntax will be eliminated after the parser transition is complete.
             var arg = app.getLhs();
-            var isSuspended = false;
+            var isSuspended = new boolean[1];
             if (arg instanceof Tree.UnaryOprApp susApp && "~".equals(susApp.getOpr().codeRepr())) {
                 arg = susApp.getRhs();
-                isSuspended = true;
+                isSuspended[0] = true;
             }
-            IR.Name name = switch (arg) {
-              case Tree.Wildcard wild -> new IR$Name$Blank(getIdentifiedLocation(wild.getToken()), meta(), diag());
-              case Tree.Ident id -> {
-                IR.Expression identifier = translateIdent(id, false);
-                yield switch (identifier) {
-                  case IR.Name name_ -> name_;
-                  default -> throw new UnhandledEntity(identifier, "translateExpression");
-                };
-              }
-              default -> throw new UnhandledEntity(arg, "translateExpressiontranslateArgumentDefinition");
-            };
+            var defaultValue = new IR.Expression[1];
+            IR.Name name = translateOldStyleLambdaArgumentName(arg, isSuspended, defaultValue);
             var arg_ = new IR$DefinitionArgument$Specified(
                     name,
                     Option.empty(),
-                    Option.empty(),
-                    isSuspended,
+                    Option.apply(defaultValue[0]),
+                    isSuspended[0],
                     getIdentifiedLocation(arg),
                     meta(),
                     diag()
@@ -528,13 +565,24 @@ final class TreeToIr {
                 Option.empty(), true, meta(), diag()
               );
             }
-            yield new IR$Function$Lambda(args, body, getIdentifiedLocation(tree), true, meta(), diag());
+            var at = expandToContain(switch (body) {
+              case IR$Expression$Block __ -> getIdentifiedLocation(tree, 0, 1);
+              default -> getIdentifiedLocation(tree);
+            }, body.location());
+            yield new IR$Function$Lambda(args, body, at, true, meta(), diag());
           }
           default -> {
             var lhs = unnamedCallArgument(app.getLhs());
             var rhs = unnamedCallArgument(app.getRhs());
+            if ("@".equals(op.codeRepr()) && lhs.value() instanceof IR$Application$Prefix fn) {
+                final Option<IdentifiedLocation> where = getIdentifiedLocation(op);
+                var err = new IR$Error$Syntax(where.get(), IR$Error$Syntax$UnrecognizedToken$.MODULE$, meta(), diag());
+                var errArg = new IR$CallArgument$Specified(Option.empty(), err, where, meta(), diag());
+                var args = cons(rhs, cons(errArg, fn.arguments()));
+                yield new IR$Application$Prefix(fn.function(), args.reverse(), false, getIdentifiedLocation(app), meta(), diag());
+            }
             var name = new IR$Name$Literal(
-              op.codeRepr(), true, getIdentifiedLocation(app), meta(), diag()
+              op.codeRepr(), true, getIdentifiedLocation(op), meta(), diag()
             );
             var loc = getIdentifiedLocation(app);
             if (lhs == null && rhs == null) {
@@ -582,6 +630,7 @@ final class TreeToIr {
           sep = "_";
         }
         var fn = new IR$Name$Literal(fnName.toString(), true, Option.empty(), meta(), diag());
+        checkArgs(args);
         yield new IR$Application$Prefix(fn, args.reverse(), false, getIdentifiedLocation(tree), meta(), diag());
       }
       case Tree.BodyBlock body -> {
@@ -610,7 +659,13 @@ final class TreeToIr {
           expressions.remove(expressions.size()-1);
         }
         var list = CollectionConverters.asScala(expressions.iterator()).toList();
-        yield new IR$Expression$Block(list, last, getIdentifiedLocation(body), false, meta(), diag());
+        var locationWithANewLine = getIdentifiedLocation(body, 0, 1);
+        if (last != null && last.location().isDefined() && last.location().get().end() != locationWithANewLine.get().end()) {
+            var patched = new Location(last.location().get().start(), locationWithANewLine.get().end() - 1);
+            var id = new IdentifiedLocation(patched, locationWithANewLine.get().id());
+            last = last.setLocation(Option.apply(id));
+        }
+        yield new IR$Expression$Block(list, last, locationWithANewLine, false, meta(), diag());
       }
       case Tree.Assignment assign -> {
         var name = buildNameOrQualifiedName(assign.getPattern());
@@ -630,6 +685,9 @@ final class TreeToIr {
           }
           last = translateExpression(expr, false);
         }
+        if (last == null) {
+            last = new IR$Name$Blank(Option.empty(), meta(), diag());
+        }
         var block = new IR$Expression$Block(expressions.reverse(), last, getIdentifiedLocation(body), false, meta(), diag());
         if (body.getLhs() != null) {
           var fn = translateExpression(body.getLhs(), isMethod);
@@ -651,7 +709,16 @@ final class TreeToIr {
         }
       }
       case Tree.TypeAnnotated anno -> translateTypeAnnotated(anno);
-      case Tree.Group group -> translateExpression(group.getBody(), false);
+      case Tree.Group group -> {
+          yield switch (translateExpression(group.getBody(), false)) {
+              case null -> new IR$Error$Syntax(getIdentifiedLocation(group).get(), IR$Error$Syntax$EmptyParentheses$.MODULE$, meta(), diag());
+              case IR$Application$Prefix pref -> {
+                  final Option<IdentifiedLocation> groupWithoutParenthesis = getIdentifiedLocation(group, 1, -1);
+                  yield pref.setLocation(groupWithoutParenthesis);
+              }
+              case IR.Expression in -> in;
+          };
+      }
       case Tree.TextLiteral txt -> translateLiteral(txt);
       case Tree.CaseOf cas -> {
         var expr = translateExpression(cas.getExpression(), false);
@@ -729,6 +796,15 @@ final class TreeToIr {
       // Documentation can be attached to an expression in a few cases, like if someone documents a line of an
       // `ArgumentBlockApplication`. The documentation is ignored.
       case Tree.Documented docu -> translateExpression(docu.getExpression());
+      case Tree.App app -> {
+          var fn = translateExpression(app.getFunc(), isMethod);
+          var loc = getIdentifiedLocation(app);
+          if (app.getArg() instanceof Tree.AutoScope) {
+              yield new IR$Application$Prefix(fn, nil(), true, loc, meta(), diag());
+          } else {
+              yield fn.setLocation(loc);
+          }
+      }
       default -> throw new UnhandledEntity(tree, "translateExpression");
     };
   }
@@ -809,9 +885,13 @@ final class TreeToIr {
 
   @SuppressWarnings("unchecked")
   private IR$Application$Prefix patchPrefixWithBlock(IR$Application$Prefix pref, IR$Expression$Block block, List<IR.CallArgument> args) {
+    if (args.nonEmpty() && args.head() == null) {
+        args = (List<IR.CallArgument>) args.tail();
+    }
     List<IR.CallArgument> allArgs = (List<IR.CallArgument>) pref.arguments().appendedAll(args.reverse());
     final IR$CallArgument$Specified blockArg = new IR$CallArgument$Specified(Option.empty(), block, block.location(), meta(), diag());
     List<IR.CallArgument> withBlockArgs = (List<IR.CallArgument>) allArgs.appended(blockArg);
+    checkArgs(withBlockArgs);
     return new IR$Application$Prefix(pref.function(), withBlockArgs, pref.hasDefaultsSuspended(), pref.location(), meta(), diag());
   }
 
@@ -1100,7 +1180,7 @@ final class TreeToIr {
     Option<List<IR$Name$Literal>> hidingNames = Option.apply(imp.getHiding()).map(
             hiding -> buildNameSequence(hiding.getBody()));
     return new IR$Module$Scope$Import$Module(
-      qualifiedName, rename, isAll, onlyNames,
+      qualifiedName, rename, isAll || onlyNames.isDefined() || hidingNames.isDefined(), onlyNames,
       hidingNames, getIdentifiedLocation(imp), false,
       meta(), diag()
     );
@@ -1188,12 +1268,36 @@ final class TreeToIr {
       default -> id;
     };
   }
+  
+  private Option<IdentifiedLocation> expandToContain(Option<IdentifiedLocation> encapsulating, Option<IdentifiedLocation> inner) {
+    if (encapsulating.isEmpty() || inner.isEmpty()) {
+      return encapsulating;
+    }
+    var en = encapsulating.get();
+    var in = inner.get();
+    if (en.start() > in.start() || en.end() < in.end()) {
+      var loc = new Location(
+        Math.min(en.start(), in.start()),
+        Math.max(en.end(), in.end())
+      );
+      return Option.apply(new IdentifiedLocation(loc, en.id()));
+    } else {
+      return encapsulating;
+    }
+  }
 
   private Option<IdentifiedLocation> getIdentifiedLocation(Tree ast) {
-    return Option.apply(ast).map(ast_ -> {
-      int begin = Math.toIntExact(ast_.getStartCode());
-      int end = Math.toIntExact(ast_.getEndCode());
-      return new IdentifiedLocation(new Location(begin, end), Option.empty());
+    return getIdentifiedLocation(ast, 0, 0);
+  }
+  private Option<IdentifiedLocation> getIdentifiedLocation(Tree ast, int b, int e) {
+    return Option.apply(switch (ast) {
+        case null -> null;
+        default -> {
+            var begin = Math.toIntExact(ast.getStartCode()) + b;
+            var end = Math.toIntExact(ast.getEndCode()) + e;
+            var someId = Option.apply(ast.uuid());
+            yield new IdentifiedLocation(new Location(begin, end), someId);
+        }
     });
   }
 
@@ -1264,4 +1368,14 @@ final class TreeToIr {
       }
     }
   }
+
+    private void checkArgs(List<IR.CallArgument> args) {
+        LinearSeq<IR.CallArgument> a = args;
+        while (!a.isEmpty()) {
+            if (a.head() == null) {
+                throw new IllegalStateException("Problem: " + args);
+            }
+            a = (LinearSeq<IR.CallArgument>) a.tail();
+        }
+    }
 }
diff --git a/engine/runtime/src/main/java/org/enso/interpreter/runtime/Module.java b/engine/runtime/src/main/java/org/enso/interpreter/runtime/Module.java
index 522ead31a96..cd681592b8f 100644
--- a/engine/runtime/src/main/java/org/enso/interpreter/runtime/Module.java
+++ b/engine/runtime/src/main/java/org/enso/interpreter/runtime/Module.java
@@ -678,4 +678,9 @@ public final class Module implements TruffleObject {
         MethodNames.Module.GET_ASSOCIATED_TYPE,
         MethodNames.Module.EVAL_EXPRESSION);
   }
+
+  @Override
+  public String toString() {
+    return "Module[" + name + ']';
+  }
 }
diff --git a/engine/runtime/src/main/scala/org/enso/compiler/core/IR.scala b/engine/runtime/src/main/scala/org/enso/compiler/core/IR.scala
index 0040641fa0b..65f343930eb 100644
--- a/engine/runtime/src/main/scala/org/enso/compiler/core/IR.scala
+++ b/engine/runtime/src/main/scala/org/enso/compiler/core/IR.scala
@@ -739,6 +739,7 @@ object IR {
             |rename = $rename,
             |onlyNames = $onlyNames,
             |hiddenNames = $hiddenNames,
+            |isAll = $isAll,
             |location = $location,
             |passData = ${this.showPassData},
             |diagnostics = $diagnostics,
@@ -7482,8 +7483,9 @@ object IR {
       @annotation.nowarn
       override val location: Option[IdentifiedLocation] =
         at match {
-          case ast: AST => ast.location.map(IdentifiedLocation(_, ast.id))
-          case _        => None
+          case ast: AST                => ast.location.map(IdentifiedLocation(_, ast.id))
+          case loc: IdentifiedLocation => Some(loc)
+          case _                       => None
         }
 
       /** @inheritdoc */
diff --git a/engine/runtime/src/test/java/org/enso/compiler/EnsoCompilerTest.java b/engine/runtime/src/test/java/org/enso/compiler/EnsoCompilerTest.java
index bba6a996e4d..bef8ad9b689 100644
--- a/engine/runtime/src/test/java/org/enso/compiler/EnsoCompilerTest.java
+++ b/engine/runtime/src/test/java/org/enso/compiler/EnsoCompilerTest.java
@@ -37,6 +37,57 @@ public class EnsoCompilerTest {
     """);
   }
 
+  @Test
+  public void testLocationsSimpleArithmeticExpression() throws Exception {
+    parseTest("""
+    main = 2 + 45 * 20
+    """, true, false, true);
+  }
+
+  @Test
+  public void testLocationsApplicationsAndMethodCalls() throws Exception {
+    parseTest("""
+    main = (2-2 == 0).if_then_else (Cons 5 6) 0
+    """, true, false, true);
+  }
+
+  @Test
+  public void testLocationsCorrectAssignmentOfVariableReads() throws Exception {
+    parseTest("""
+    main =
+        x = 2 + 2 * 2
+        y = x * x
+        IO.println y
+    """, true, false, true);
+  }
+
+  @Test
+  public void testLocationsDeeplyNestedFunctions() throws Exception {
+    parseTest("""
+        foo = a -> b ->
+            IO.println a
+        """, true, false, true);
+  }
+
+  @Test
+  public void testLocationsDeeplyNestedFunctionsNoBlock() throws Exception {
+    parseTest("""
+    Nothing.method =
+        add = a -> b -> a + b
+
+    main = Nothing.method
+    """, true, false, true);
+  }
+
+  @Test
+  @Ignore
+  public void testSpacesAtTheEndOfFile() throws Exception {
+    var fourSpaces = "    ";
+    parseTest("""
+    main = add_ten 5
+    """ + fourSpaces);
+  }
+
   @Test
   public void testCase() throws Exception {
     parseTest("""
@@ -86,6 +137,13 @@ public class EnsoCompilerTest {
     """);
   }
 
+  @Test
+  public void testImportTrue() throws Exception {
+    parseTest("""
+    from Standard.Base import True
+    """);
+  }
+
   @Test
   public void testMeaningOfWorld() throws Exception {
     parseTest("""
@@ -483,6 +541,27 @@ public class EnsoCompilerTest {
         """);
   }
 
+  @Test
+  public void testEmptyGroup() throws Exception {
+    parseTest("""
+    main =
+        x = Panic.catch_primitive () .convert_to_dataflow_error
+        x.catch_primitive err->
+            case err of
+                Syntax_Error_Data msg -> "Oopsie, it's a syntax error: " + msg
+    """);
+  }
+
+  @Test
+  public void testEmptyGroup2AndAtSymbol() throws Exception {
+    parseTest("""
+    main =
+        x = ()
+        x = 5
+        y = @
+    """);
+  }
+
   @Test
   public void testTestGroupSimple() throws Exception {
     parseTest("""
@@ -493,6 +572,15 @@ public class EnsoCompilerTest {
     """);
   }
 
+  @Test
+  public void testNotAnOperator() throws Exception {
+    parseTest("""
+    main =
+        x = Panic.catch_primitive @ caught_panic-> caught_panic.payload
+        x.to_text
+    """);
+  }
+
   @Test
   public void testWildcardLeftHandSide() throws Exception {
     parseTest("""
@@ -788,6 +876,21 @@ public class EnsoCompilerTest {
         """);
   }
 
+  @Test
+  public void testAutoScope2() throws Exception {
+    parseTest("""
+    fn1 = fn ...
+    fn2 = fn 1 ...
+    """);
+  }
+
+  @Test
+  public void testForcedTerms() throws Exception {
+    parseTest("""
+    ifTest = c -> (~ifT) -> ~ifF -> if c == 0 then ifT else ifF
+    """);
+  }
+
   @Test
   public void testTextArrayType() throws Exception {
     parseTest("""
@@ -894,6 +997,13 @@ public class EnsoCompilerTest {
     """);
   }
 
+  @Test
+  public void testSidesPlus() throws Exception {
+    parseTest("""
+    result = reduce (+)
+    """);
+  }
+
   @Test
   public void testConstructorMultipleNamedArgs1() throws Exception {
     parseTest("""
@@ -925,48 +1035,107 @@ public class EnsoCompilerTest {
     """);
   }
 
-  static String simplifyIR(IR i) {
-    var txt = i.pretty().replaceAll("id = [0-9a-f\\-]*", "id = _");
-    for (;;) {
-      final String pref = "IdentifiedLocation(";
-      int at = txt.indexOf(pref);
-      if (at == -1) {
-        break;
-      }
-      int to = at + pref.length();
-      int depth = 1;
-      while (depth > 0) {
-        switch (txt.charAt(to)) {
-          case '(' -> depth++;
-          case ')' -> depth--;
+  @Test
+  public void testGroupArgument() throws Exception {
+    parseTest("""
+    foo = x -> (y = bar x) -> x + y
+    """);
+  }
+
+  @Test
+  @Ignore
+  public void testResolveExecutionContext() throws Exception {
+    parseTest("""
+    foo : A -> B -> C in Input
+    """);
+  }
+
+  @Test
+  public void testSugaredFunctionDefinition() throws Exception {
+    parseTest("""
+    main =
+        f a b = a - b
+        f 10 20
+    """);
+  }
+
+  @Test
+  @Ignore
+  public void testInThePresenceOfComments() throws Exception {
+    parseTest("""
+    # this is a comment
+    #this too
+    ## But this is a doc.
+    main = # define main
+        y = 1 # assign one to `y`
+        x = 2 # assign two to #x
+        # perform the addition
+        x + y # the addition is performed here
+    """);
+  }
+
+  static String simplifyIR(IR i, boolean noIds, boolean noLocations, boolean lessDocs) {
+    var txt = i.pretty();
+    if (noIds) {
+      txt = txt.replaceAll("id = [0-9a-f\\-]*", "id = _");
+    }
+    if (noLocations) {
+        for (;;) {
+          final String pref = "IdentifiedLocation(";
+          int at = txt.indexOf(pref);
+          if (at == -1) {
+            break;
+          }
+          int to = at + pref.length();
+          int depth = 1;
+          while (depth > 0) {
+            switch (txt.charAt(to)) {
+              case '(' -> depth++;
+              case ')' -> depth--;
+            }
+            to++;
+          }
+          txt = txt.substring(0, at) + "IdentifiedLocation[_]" + txt.substring(to);
+        }
+    }
+    if (lessDocs) {
+        for (;;) {
+          final String pref = "IR.Comment.Documentation(";
+          int at = txt.indexOf(pref);
+          if (at == -1) {
+            break;
+          }
+          int to = txt.indexOf("location =", at + pref.length());
+          txt = txt.substring(0, at) + "IR.Comment.Doc(" + txt.substring(to);
+        }
+        for (;;) {
+          final String pref = "IR.Case.Pattern.Doc(";
+          int at = txt.indexOf(pref);
+          if (at == -1) {
+            break;
+          }
+          int to = txt.indexOf("location =", at + pref.length());
+          txt = txt.substring(0, at) + "IR.Comment.CaseDoc(" + txt.substring(to);
         }
-        to++;
-      }
-      txt = txt.substring(0, at) + "IdentifiedLocation[_]" + txt.substring(to);
     }
     for (;;) {
-      final String pref = "IR.Comment.Documentation(";
+      final String pref = "IR.Error.Syntax(";
       int at = txt.indexOf(pref);
       if (at == -1) {
         break;
       }
-      int to = txt.indexOf("location =", at + pref.length());
-      txt = txt.substring(0, at) + "IR.Comment.Doc(" + txt.substring(to);
-    }
-    for (;;) {
-      final String pref = "IR.Case.Pattern.Doc(";
-      int at = txt.indexOf(pref);
-      if (at == -1) {
-        break;
-      }
-      int to = txt.indexOf("location =", at + pref.length());
-      txt = txt.substring(0, at) + "IR.Comment.CaseDoc(" + txt.substring(to);
+      int to = txt.indexOf("reason =", at + pref.length());
+      txt = txt.substring(0, at) + "IR.Error.Syntax (" + txt.substring(to);
     }
     return txt;
   }
 
+  private static void parseTest(String code) throws IOException {
+      parseTest(code, true, true, true);
+  }
+
   @SuppressWarnings("unchecked")
-  static void parseTest(String code) throws IOException {
+  private static void parseTest(String code, boolean noIds, boolean noLocations, boolean lessDocs) throws IOException {
     var src = Source.newBuilder("enso", code, "test-" + Integer.toHexString(code.hashCode()) + ".enso").build();
     var ir = ensoCompiler.compile(src);
     assertNotNull("IR was generated", ir);
@@ -974,7 +1143,7 @@ public class EnsoCompilerTest {
     var oldAst = new Parser().runWithIds(src.getCharacters().toString());
     var oldIr = AstToIr.translate((ASTOf<Shape>)(Object)oldAst);
 
-    Function<IR, String> filter = EnsoCompilerTest::simplifyIR;
+    Function<IR, String> filter = (f) -> simplifyIR(f, noIds, noLocations, lessDocs);
 
     var old = filter.apply(oldIr);
     var now = filter.apply(ir);
diff --git a/engine/runtime/src/test/java/org/enso/compiler/ParseStdLibTest.java b/engine/runtime/src/test/java/org/enso/compiler/ParseStdLibTest.java
index 9a9083d4c58..b177142fda1 100644
--- a/engine/runtime/src/test/java/org/enso/compiler/ParseStdLibTest.java
+++ b/engine/runtime/src/test/java/org/enso/compiler/ParseStdLibTest.java
@@ -118,7 +118,7 @@ public final class ParseStdLibTest extends TestCase {
     var oldAst = new Parser().runWithIds(src.getCharacters().toString());
     var oldIr = AstToIr.translate((ASTOf<Shape>) (Object) oldAst);
 
-    Function<IR, String> filter = EnsoCompilerTest::simplifyIR;
+    Function<IR, String> filter = (f) -> EnsoCompilerTest.simplifyIR(f, true, true, true);
 
     var old = filter.apply(oldIr);
     var now = filter.apply(ir);
diff --git a/engine/runtime/src/test/java/org/enso/interpreter/test/CodeLocationsTestInstrument.java b/engine/runtime/src/test/java/org/enso/interpreter/test/CodeLocationsTestInstrument.java
index 2577d7fa84a..b830e7d7060 100644
--- a/engine/runtime/src/test/java/org/enso/interpreter/test/CodeLocationsTestInstrument.java
+++ b/engine/runtime/src/test/java/org/enso/interpreter/test/CodeLocationsTestInstrument.java
@@ -8,6 +8,8 @@ import com.oracle.truffle.api.instrumentation.SourceSectionFilter;
 import com.oracle.truffle.api.instrumentation.TruffleInstrument;
 import com.oracle.truffle.api.nodes.Node;
 import com.oracle.truffle.api.source.SourceSection;
+import java.util.LinkedHashSet;
+import java.util.Set;
 
 /**
  * A debug instrument used to test code locations.
@@ -40,12 +42,17 @@ public class CodeLocationsTestInstrument extends TruffleInstrument {
   public static class LocationsEventListener implements ExecutionEventListener {
     private boolean successful = false;
     private final int start;
+    private final int diff;
     private final int length;
+    private final int lengthDiff;
     private final Class<?> type;
+    private final Set<SourceSection> close = new LinkedHashSet<>();
 
-    private LocationsEventListener(int start, int length, Class<?> type) {
+    private LocationsEventListener(int start, int diff, int length, int lengthDiff, Class<?> type) {
       this.start = start;
+      this.diff = diff;
       this.length = length;
+      this.lengthDiff = lengthDiff;
       this.type = type;
     }
 
@@ -86,6 +93,20 @@ public class CodeLocationsTestInstrument extends TruffleInstrument {
       return successful;
     }
 
+    /**
+     * List collected {@link SourceSection} instances that were close to searched for location, but
+     * not fully right.
+     *
+     * @return textual dump of those sections
+     */
+    public String dumpCloseSections() {
+      var sb = new StringBuilder();
+      for (var s : close) {
+        sb.append("\n").append(s.toString());
+      }
+      return sb.toString();
+    }
+
     /**
      * Checks if the node to be executed is the node this listener was created to observe.
      *
@@ -105,8 +126,11 @@ public class CodeLocationsTestInstrument extends TruffleInstrument {
       if (section == null || !section.hasCharIndex()) {
         return;
       }
-      if (section.getCharIndex() == start && section.getCharLength() == length) {
+      if (Math.abs(section.getCharIndex() - start) <= diff
+          && Math.abs(section.getCharLength() - length) <= lengthDiff) {
         successful = true;
+      } else {
+        close.add(section);
       }
     }
 
@@ -122,14 +146,16 @@ public class CodeLocationsTestInstrument extends TruffleInstrument {
    * Attach a new listener to observe nodes with given parameters.
    *
    * @param sourceStart the source start location of the expected node
+   * @param diff acceptable diff
    * @param length the source length of the expected node
    * @param type the type of the expected node
    * @return a reference to attached event listener
    */
-  public EventBinding<LocationsEventListener> bindTo(int sourceStart, int length, Class<?> type) {
+  public EventBinding<LocationsEventListener> bindTo(
+      int sourceStart, int diff, int length, int lengthDiff, Class<?> type) {
     return env.getInstrumenter()
         .attachExecutionEventListener(
             SourceSectionFilter.newBuilder().indexIn(sourceStart, length).build(),
-            new LocationsEventListener(sourceStart, length, type));
+            new LocationsEventListener(sourceStart, diff, length, lengthDiff, type));
   }
 }
diff --git a/engine/runtime/src/test/scala/org/enso/interpreter/test/InterpreterTest.scala b/engine/runtime/src/test/scala/org/enso/interpreter/test/InterpreterTest.scala
index ce0f7b681e2..5790d959f95 100644
--- a/engine/runtime/src/test/scala/org/enso/interpreter/test/InterpreterTest.scala
+++ b/engine/runtime/src/test/scala/org/enso/interpreter/test/InterpreterTest.scala
@@ -33,7 +33,16 @@ case class LocationsInstrumenter(instrument: CodeLocationsTestInstrument) {
   var bindings: List[EventBinding[LocationsEventListener]] = List()
 
   def assertNodeExists(start: Int, length: Int, kind: Class[_]): Unit =
-    bindings ::= instrument.bindTo(start, length, kind)
+    assertNodeExists(start, 0, length, 0, kind)
+
+  def assertNodeExists(
+    start: Int,
+    diff: Int,
+    length: Int,
+    lengthDiff: Int,
+    kind: Class[_]
+  ): Unit =
+    bindings ::= instrument.bindTo(start, diff, length, lengthDiff, kind)
 
   def verifyResults(): Unit = {
     bindings.foreach { binding =>
@@ -41,7 +50,8 @@ case class LocationsInstrumenter(instrument: CodeLocationsTestInstrument) {
       if (!listener.isSuccessful) {
         Assertions.fail(
           s"Node of type ${listener.getType.getSimpleName} at position " +
-          s"${listener.getStart} with length ${listener.getLength} was not found."
+          s"${listener.getStart} with length ${listener.getLength} was not found." +
+          s"${listener.dumpCloseSections()}"
         )
       }
     }
diff --git a/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/CodeLocationsTest.scala b/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/CodeLocationsTest.scala
index b17136ce9e3..8846ae6b373 100644
--- a/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/CodeLocationsTest.scala
+++ b/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/CodeLocationsTest.scala
@@ -130,7 +130,7 @@ class CodeLocationsTest extends InterpreterTest {
           |
           |    foo x + foo y
           |""".stripMargin
-      instrumenter.assertNodeExists(121, 109, classOf[CaseNode])
+      instrumenter.assertNodeExists(121, 0, 109, 1, classOf[CaseNode])
       instrumenter.assertNodeExists(167, 7, classOf[ApplicationNode])
       instrumenter.assertNodeExists(187, 9, classOf[AssignmentNode])
       instrumenter.assertNodeExists(224, 5, classOf[ApplicationNode])
@@ -190,7 +190,7 @@ class CodeLocationsTest extends InterpreterTest {
     "be correct for negated literals" in
     withLocationsInstrumenter { instrumenter =>
       val code = "main = (-1)"
-      instrumenter.assertNodeExists(8, 2, classOf[LiteralNode])
+      instrumenter.assertNodeExists(7, 1, 4, 2, classOf[LiteralNode])
       eval(code)
     }
 
@@ -202,7 +202,7 @@ class CodeLocationsTest extends InterpreterTest {
           |    f = 1
           |    -f
           |""".stripMargin
-      instrumenter.assertNodeExists(22, 2, classOf[ApplicationNode])
+      instrumenter.assertNodeExists(22, 1, 2, 1, classOf[ApplicationNode])
       eval(code)
     }
 
@@ -223,7 +223,10 @@ class CodeLocationsTest extends InterpreterTest {
       ) shouldEqual 1
       method.value.invokeMember(
         MethodNames.Function.GET_SOURCE_LENGTH
-      ) shouldEqual 24
+      ) should (
+        equal(24) or
+        equal(25)
+      )
 
       instrumenter.assertNodeExists(16, 9, classOf[ApplicationNode])
 
@@ -233,14 +236,13 @@ class CodeLocationsTest extends InterpreterTest {
     "be correct in sugared function definitions" in
     withLocationsInstrumenter { instrumenter =>
       val code =
-        """
-          |main =
-          |    f a b = a - b
-          |    f 10 20
-          |""".stripMargin
+        """|main =
+           |    f a b = a - b
+           |    f 10 20
+           |""".stripMargin
 
-      instrumenter.assertNodeExists(12, 13, classOf[AssignmentNode])
-      instrumenter.assertNodeExists(20, 5, classOf[ApplicationNode])
+      instrumenter.assertNodeExists(11, 1, 13, 0, classOf[AssignmentNode])
+      instrumenter.assertNodeExists(19, 1, 5, 0, classOf[ApplicationNode])
       eval(code)
     }
 
diff --git a/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/ConstructorsTest.scala b/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/ConstructorsTest.scala
index 4e2356f67e2..daf8cbd7470 100644
--- a/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/ConstructorsTest.scala
+++ b/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/ConstructorsTest.scala
@@ -22,7 +22,7 @@ class ConstructorsTest extends InterpreterTest {
           |    case x of
           |        Cons h t -> h
           |        Nil -> 0
-      """.stripMargin
+          |""".stripMargin
       eval(patternMatchingCode) shouldEqual 1
     }
 
@@ -37,7 +37,7 @@ class ConstructorsTest extends InterpreterTest {
           |        Nil -> 0
           |
           |    sumList (genList 10)
-      """.stripMargin
+          |""".stripMargin
       eval(testCode) shouldEqual 55
     }
 
@@ -53,7 +53,7 @@ class ConstructorsTest extends InterpreterTest {
           |        Cons x y -> add x y
           |
           |    result + 1
-      """.stripMargin
+          |""".stripMargin
       eval(testCode) shouldEqual 4
     }
 
@@ -66,7 +66,7 @@ class ConstructorsTest extends InterpreterTest {
           |    case nil of
           |        Cons _ _ -> 0
           |        _ -> 1
-      """.stripMargin
+          |""".stripMargin
       eval(testCode) shouldEqual 1
     }
 
@@ -78,7 +78,7 @@ class ConstructorsTest extends InterpreterTest {
           |    nil = Nil
           |    case nil of
           |        Cons h t -> 0
-      """.stripMargin
+          |""".stripMargin
       the[InterpreterException] thrownBy eval(testCode)
         .call() should have message "Inexhaustive pattern match: no branch matches Nil."
     }
@@ -100,7 +100,7 @@ class ConstructorsTest extends InterpreterTest {
           |  Nil2 -> 0
           |
           |main = Nothing.sumList (Nothing.genList 10)
-      """.stripMargin
+          |""".stripMargin
       eval(testCode) shouldEqual 55
     }
   }
diff --git a/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/GlobalScopeTest.scala b/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/GlobalScopeTest.scala
index 1c6e740532c..29f1942cdd8 100644
--- a/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/GlobalScopeTest.scala
+++ b/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/GlobalScopeTest.scala
@@ -18,7 +18,7 @@ class GlobalScopeTest extends InterpreterTest {
           |Nothing.add_ten = b -> Nothing.a + b
           |
           |main = Nothing.add_ten 5
-        """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual 15
     }
@@ -35,7 +35,7 @@ class GlobalScopeTest extends InterpreterTest {
           |        doubled = res * multiply
           |        doubled
           |    fn 2
-        """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual 6
     }
@@ -51,7 +51,7 @@ class GlobalScopeTest extends InterpreterTest {
           |  result
           |
           |main = Nothing.binaryFn 1 2 (a -> b -> Nothing.adder a b)
-        """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual 3
     }
@@ -68,7 +68,7 @@ class GlobalScopeTest extends InterpreterTest {
           |  if (number % 3) == 0 then number else Nothing.decrementCall number
           |
           |main = Nothing.fn1 5
-        """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual 3
     }
@@ -81,7 +81,7 @@ class GlobalScopeTest extends InterpreterTest {
           |
           |Nothing.b = Nothing.a
           |main = .b
-        """.stripMargin
+          |""".stripMargin
 
       noException should be thrownBy eval(code)
     }
diff --git a/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/LambdaTest.scala b/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/LambdaTest.scala
index 4af6000acea..9cc75516ca3 100644
--- a/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/LambdaTest.scala
+++ b/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/LambdaTest.scala
@@ -27,7 +27,7 @@ class LambdaTest extends InterpreterTest {
           |    add = a -> b -> a + b
           |    adder = b -> add a b
           |    adder 2
-      """.stripMargin
+          |""".stripMargin
 
       eval(code).call(3) shouldEqual 5
     }
@@ -46,7 +46,7 @@ class LambdaTest extends InterpreterTest {
           |main =
           |    sumTo = x -> if x == 0 then 0 else x + (sumTo (x-1))
           |    sumTo 10
-      """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual 55
     }
diff --git a/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/NamedArgumentsTest.scala b/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/NamedArgumentsTest.scala
index 450fc35a204..7adf2215d84 100644
--- a/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/NamedArgumentsTest.scala
+++ b/engine/runtime/src/test/scala/org/enso/interpreter/test/semantic/NamedArgumentsTest.scala
@@ -21,7 +21,7 @@ class NamedArgumentsTest extends InterpreterTest {
           |Nothing.add_ten = b -> Nothing.a + b
           |
           |main = Nothing.add_ten (b = 10)
-      """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual 20
     }
@@ -33,7 +33,7 @@ class NamedArgumentsTest extends InterpreterTest {
           |Nothing.subtract = a -> b -> a - b
           |
           |main = Nothing.subtract (b = 10) (a = 5)
-    """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual -5
     }
@@ -46,7 +46,7 @@ class NamedArgumentsTest extends InterpreterTest {
           |    addTen = num -> num + a
           |    res = addTen (num = a)
           |    res
-    """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual 20
     }
@@ -58,7 +58,7 @@ class NamedArgumentsTest extends InterpreterTest {
           |Nothing.add_num = a -> (num = 10) -> a + num
           |
           |main = Nothing.add_num 5
-    """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual 15
     }
@@ -96,7 +96,7 @@ class NamedArgumentsTest extends InterpreterTest {
           |Nothing.add_together = (a = 5) -> (b = 6) -> a + b
           |
           |main = Nothing.add_together
-    """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual 11
     }
@@ -108,7 +108,7 @@ class NamedArgumentsTest extends InterpreterTest {
           |Nothing.add_num = a -> (num = 10) -> a + num
           |
           |main = Nothing.add_num 1 (num = 1)
-    """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual 2
     }
@@ -136,7 +136,7 @@ class NamedArgumentsTest extends InterpreterTest {
           |  res
           |
           |main = Nothing.summer 100
-    """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual 5050
     }
@@ -206,7 +206,7 @@ class NamedArgumentsTest extends InterpreterTest {
           |        Nil2 -> 0
           |
           |    sum (gen_list 10)
-        """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual 55
     }
@@ -226,7 +226,7 @@ class NamedArgumentsTest extends InterpreterTest {
           |        Nil2 -> 0
           |
           |    sum (gen_list 5)
-        """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual 15
     }
@@ -257,7 +257,7 @@ class NamedArgumentsTest extends InterpreterTest {
           |  Nil2 -> 0
           |
           |main = Nothing.sum_list (C2.Cons2 10)
-        """.stripMargin
+          |""".stripMargin
 
       eval(code) shouldEqual 10
     }