Merge branch 'topic/lkql_stack_trace' into 'master'

Add a call-stack to LKQL error message

Closes #10

See merge request eng/libadalang/langkit-query-language!244

Author: HugoGGuerrier

lkql_jit/language/src/main/java/com/adacore/lkql_jit/LKQLContext.java

@@ -13,6 +13,7 @@
 import com.adacore.lkql_jit.exception.LKQLRuntimeException;
 import com.adacore.lkql_jit.options.JsonUtils;
 import com.adacore.lkql_jit.options.RuleInstance;
+import com.adacore.lkql_jit.runtime.CallStack;
 import com.adacore.lkql_jit.runtime.GlobalScope;
 import com.adacore.lkql_jit.utils.Constants;
 import com.adacore.lkql_jit.utils.functions.ArrayUtils;
@@ -43,6 +44,9 @@ public final class LKQLContext {
 
     public final CheckerUtils.SourceLinesCache linesCache = new CheckerUtils.SourceLinesCache();
 
+    /** The call stack of the current language thread. */
+    public final CallStack callStack = new CallStack();
+
     // ----- Ada project attributes -----
 
     /** The analysis context for the ada files. */

lkql_jit/language/src/main/java/com/adacore/lkql_jit/checker/utils/CheckerUtils.java

@@ -9,6 +9,7 @@
 import com.adacore.lkql_jit.LKQLContext;
 import com.adacore.lkql_jit.LKQLLanguage;
 import com.adacore.lkql_jit.checker.BaseChecker;
+import com.adacore.lkql_jit.runtime.CallStack;
 import com.adacore.lkql_jit.utils.functions.FileUtils;
 import com.adacore.lkql_jit.utils.functions.StringUtils;
 import com.adacore.lkql_jit.utils.source_location.SourceLocation;
@@ -87,6 +88,23 @@ String diagnostic(
                 SourceLocation lkqlErrorLocation,
                 String ruleName);
 
+        /** Given a call stack, returns a formatted representation of this stack. */
+        default String callStack(CallStack callStack) {
+            StringBuilder res = new StringBuilder();
+            for (int i = 0; i < callStack.calls.size(); i++) {
+                var call = callStack.calls.get(i);
+
+                // Add a newline of we're not on the first call
+                if (i > 0) {
+                    res.append('\n');
+                }
+
+                // Format the current call and add it to the result
+                res.append(" in ").append(call.display());
+            }
+            return res.toString();
+        }
+
         /**
          * Emit a diagnostic. Location parameters can be null. If both are null, then a non located
          * diagnostic will be emitted. The ruleName can also be "", in which case the diagnostic

lkql_jit/language/src/main/java/com/adacore/lkql_jit/exception/LKQLRuntimeException.java

@@ -7,6 +7,7 @@
 
 import com.adacore.lkql_jit.LKQLLanguage;
 import com.adacore.lkql_jit.checker.utils.CheckerUtils;
+import com.adacore.lkql_jit.runtime.CallStack;
 import com.adacore.lkql_jit.utils.source_location.SourceLocation;
 import com.adacore.lkql_jit.utils.source_location.SourceSectionWrapper;
 import com.oracle.truffle.api.CompilerDirectives;
@@ -25,10 +26,14 @@ public final class LKQLRuntimeException extends AbstractTruffleException {
 
     @Serial private static final long serialVersionUID = 8401390548003855662L;
 
+    /** The state of the call stack when the exception has been raised. */
+    public final CallStack callStack;
+
     // ----- Constructors -----
 
     private LKQLRuntimeException(String message, Node location) {
         super(message, location);
+        this.callStack = LKQLLanguage.getContext(null).callStack.clone();
     }
 
     // ----- Exception creation methods -----
@@ -382,6 +387,8 @@ public static LKQLRuntimeException positionAfterNamedArgument(Node location) {
                 "positional argument after named argument", location);
     }
 
+    // ----- Instance methods -----
+
     public SourceLocation getSourceLoc() {
         var loc = getLocation();
         return loc != null ? new SourceSectionWrapper(getLocation().getSourceSection()) : null;
@@ -407,9 +414,9 @@ public String getErrorMessage() {
     @Override
     public String getMessage() {
         var loc = getSourceLoc();
-        return LKQLLanguage.getContext(null)
-                .getDiagnosticEmitter()
-                .diagnostic(
-                        CheckerUtils.MessageKind.ERROR, this.getErrorMessage(), null, loc, null);
+        var diagEmitter = LKQLLanguage.getContext(null).getDiagnosticEmitter();
+        return diagEmitter.diagnostic(
+                        CheckerUtils.MessageKind.ERROR, this.getErrorMessage(), null, loc, null)
+                + (this.callStack.isEmpty() ? "" : "\n" + diagEmitter.callStack(this.callStack));
     }
 }

lkql_jit/language/src/main/java/com/adacore/lkql_jit/nodes/expressions/FunCall.java

@@ -5,6 +5,7 @@
 
 package com.adacore.lkql_jit.nodes.expressions;
 
+import com.adacore.lkql_jit.LKQLLanguage;
 import com.adacore.lkql_jit.built_ins.BuiltInFunctionValue;
 import com.adacore.lkql_jit.built_ins.BuiltInMethodValue;
 import com.adacore.lkql_jit.built_ins.values.*;
@@ -229,14 +230,27 @@ private Object executeLKQLFunction(
         // We don't place the closure in the arguments because built-ins don't have any.
         // Just execute the function.
         try {
+            pushCallStack(function);
             return functionLibrary.execute(function, args);
         } catch (ArityException | UnsupportedTypeException | UnsupportedMessageException e) {
             // TODO: Implement runtime checks in the LKQLFunction class and base computing on them
             // (#138)
             throw LKQLRuntimeException.fromJavaException(e, this.getCallee());
+        } finally {
+            popCallStack();
         }
     }
 
+    /** Push this call node to the call stack. */
+    private void pushCallStack(LKQLFunction function) {
+        LKQLLanguage.getContext(this).callStack.pushCall(function, this);
+    }
+
+    /** Remove this call node from the call stack. */
+    private void popCallStack() {
+        LKQLLanguage.getContext(this).callStack.popCall();
+    }
+
     // ----- Override methods -----
 
     /**

lkql_jit/language/src/main/java/com/adacore/lkql_jit/runtime/CallStack.java

@@ -0,0 +1,60 @@
+//
+//  Copyright (C) 2005-2024, AdaCore
+//  SPDX-License-Identifier: GPL-3.0-or-later
+//
+
+package com.adacore.lkql_jit.runtime;
+
+import com.adacore.lkql_jit.built_ins.values.LKQLFunction;
+import com.adacore.lkql_jit.nodes.expressions.FunCall;
+import com.oracle.truffle.api.CompilerDirectives;
+import java.util.LinkedList;
+
+/** This class represents a call stack for the LKQL language. */
+public final class CallStack implements Cloneable {
+
+    // ----- Attributes -----
+
+    /** This is where all calls are stored. */
+    public final LinkedList<Element> calls = new LinkedList<>();
+
+    // ----- Instance methods -----
+
+    public boolean isEmpty() {
+        return this.calls.isEmpty();
+    }
+
+    @CompilerDirectives.TruffleBoundary
+    public void pushCall(LKQLFunction function, FunCall call) {
+        this.calls.addFirst(new Element(function, call));
+    }
+
+    @CompilerDirectives.TruffleBoundary
+    public void popCall() {
+        this.calls.removeFirst();
+    }
+
+    // ----- Override methods -----
+
+    @Override
+    public CallStack clone() {
+        var res = new CallStack();
+        res.calls.addAll(this.calls);
+        return res;
+    }
+
+    // ----- Inner classes -----
+
+    /**
+     * An element of a call stack is an association between an LKQL functional value and a call
+     * node.
+     */
+    public record Element(LKQLFunction function, FunCall call) {
+        public String display() {
+            return this.function.getName()
+                    + " (called at "
+                    + this.call.getLocation().display()
+                    + ")";
+        }
+    }
+}

testsuite/tests/interpreter/sublist_builtin/test.out

@@ -5,3 +5,4 @@
 script.lkql:6:7: error: Invalid index: 0
 6 | print(l.sublist(0, 5))
   |       ^^^^^^^^^^^^^^^
+ in sublist (called at script.lkql:6:7)

testsuite/tests/interpreter_errors/call_stack/script.lkql

@@ -0,0 +1,4 @@
+fun error() = null.not_a_field()
+fun call_error() = error()
+fun call_call_error() = call_error()
+call_call_error()

testsuite/tests/interpreter_errors/call_stack/test.out

@@ -0,0 +1,6 @@
+script.lkql:1:15: error: Null receiver in dot access
+1 | fun error() = null.not_a_field()
+  |               ^^^^^^^^^^^^^^^^
+ in error (called at script.lkql:2:20)
+ in call_error (called at script.lkql:3:25)
+ in call_call_error (called at script.lkql:4:1)

testsuite/tests/interpreter_errors/call_stack/test.yaml

@@ -0,0 +1,2 @@
+driver: 'interpreter'
+project: 'default_project/default.gpr'