Encompass child node's location in parent.

Closes #1893

When a child is added with `addChild`, the parent's location should
(generally) span over that child as well. This primarily helps for cases
where a node doesn't have much of a location until it gets children
added - like `AttributeSet`. The locations for those should encompass
all of the attributes within the set. That logic applies for any node
with a child: if it's the child, then its location should reflect that.

hilti/toolchain/include/ast/attribute.h

@@ -136,7 +136,10 @@ class AttributeSet : public Node {
     bool has(std::string_view tag) const { return find(tag) != nullptr; }
 
     /** Adds an attribute to the set. */
-    void add(ASTContext* ctx, Attribute* a) { addChild(ctx, a); }
+    void add(ASTContext* ctx, Attribute* a) {
+        addChild(ctx, a);
+        combineLocations(a);
+    }
 
     /** Removes all attributes of the given tag. */
     void remove(std::string_view tag);

hilti/toolchain/include/ast/location.h

@@ -44,6 +44,12 @@ class Location {
     auto from() const { return _from_line; }
     auto to() const { return _to_line; }
 
+    /**
+     * Merges this Location with the provided location. Returns new a location
+     * which encompasses the entire span.
+     */
+    Location mergedRange(const Location& loc) const;
+
     /**
      * Returns a string representation of the location.
      *

hilti/toolchain/include/ast/node.h

@@ -8,7 +8,6 @@
 #include <memory>
 #include <optional>
 #include <ostream>
-#include <set>
 #include <string>
 #include <unordered_set>
 #include <utility>
@@ -502,6 +501,16 @@ class Node {
         n->retain();
     }
 
+    /**
+     * Updates this Node's location to encompass the other Node's location.
+     *
+     * @param other the node whose location will get merged
+     */
+    void combineLocations(const Node* other) {
+        auto meta = Meta(_meta->location().mergedRange(other->location()), _meta->comments());
+        setMeta(std::move(meta));
+    }
+
     /**
      * Adds a series of child nodes. This operates like calling `addChild()` on
      * each of them individually.

hilti/toolchain/src/ast/location.cc

@@ -9,6 +9,19 @@ const Location location::None;
 
 Location::operator bool() const { return _file != location::None._file; }
 
+Location Location::mergedRange(const Location& loc) const {
+    if ( _file != loc._file )
+        return *this;
+
+    auto [from_line, from_character] =
+        std::min(std::tie(_from_line, _from_character), std::tie(loc._from_line, loc._from_character));
+
+    auto [to_line, to_character] =
+        std::max(std::tie(_to_line, _to_character), std::tie(loc._to_line, loc._to_character));
+
+    return Location(_file, from_line, to_line, from_character, to_character);
+}
+
 std::string Location::dump(bool no_path) const {
     if ( ! *this )
         return "<no location>";

spicy/toolchain/src/compiler/validator.cc

@@ -363,8 +363,7 @@ struct VisitorPost : visitor::PreOrder, hilti::validator::VisitorMixIn {
         const bool isAlias = n->type()->print() != n->typeID().str();
         if ( isAlias ) {
             if ( ! n->attributes()->attributes().empty() )
-                // TODO(#1893): This should diagnose on the attribute set
-                error("attributes are not allow on type aliases", n);
+                error("attributes are not allowed on type aliases", n->attributes());
         }
 
         if ( n->linkage() == hilti::declaration::Linkage::Public && n->type()->alias() ) {

tests/Baseline/spicy.attributes.invalid-type-attributes/output

@@ -1,6 +1,6 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
-[error] <...>/invalid-type-attributes.spicy:11:1-11:23: attributes are not allow on type aliases
-[error] <...>/invalid-type-attributes.spicy:12:1-12:23: attributes are not allow on type aliases
-[error] <...>/invalid-type-attributes.spicy:15:1-15:46: attributes are not allow on type aliases
-[error] <...>/invalid-type-attributes.spicy:16:1-16:53: attributes are not allow on type aliases
+[error] <...>/invalid-type-attributes.spicy:11:17-11:22: attributes are not allowed on type aliases
+[error] <...>/invalid-type-attributes.spicy:12:15-12:22: attributes are not allowed on type aliases
+[error] <...>/invalid-type-attributes.spicy:15:28-15:45: attributes are not allowed on type aliases
+[error] <...>/invalid-type-attributes.spicy:16:20-16:52: attributes are not allowed on type aliases
 [error] spicyc: aborting after errors