Relax INSERT-SELECT to work with partial select statements (pointfreeco#89)

This allows you to insert from compound selects, values, and more.

Author: stephencelis

Sources/StructuredQueriesCore/Statements/Insert.swift

@@ -303,13 +303,11 @@ extension Table {
     V1,
     each V2,
     C1: QueryExpression,
-    each C2: QueryExpression,
-    From,
-    Joins
+    each C2: QueryExpression
   >(
     or conflictResolution: ConflictResolution? = nil,
     _ columns: (TableColumns) -> (TableColumn<Self, V1>, repeat TableColumn<Self, each V2>),
-    select selection: () -> Select<(C1, repeat each C2), From, Joins>,
+    select selection: () -> some PartialSelectStatement<(C1, repeat each C2)>,
     onConflictDoUpdate updates: ((inout Updates<Self>) -> Void)? = nil,
     @QueryFragmentBuilder<Bool>
     where updateFilter: (TableColumns) -> [QueryFragment] = { _ in [] }
@@ -346,14 +344,12 @@ extension Table {
     each V2,
     C1: QueryExpression,
     each C2: QueryExpression,
-    From,
-    Joins,
     T1,
     each T2
   >(
     or conflictResolution: ConflictResolution? = nil,
     _ columns: (TableColumns) -> (TableColumn<Self, V1>, repeat TableColumn<Self, each V2>),
-    select selection: () -> Select<(C1, repeat each C2), From, Joins>,
+    select selection: () -> some PartialSelectStatement<(C1, repeat each C2)>,
     onConflict conflictTargets: (TableColumns) -> (
       TableColumn<Self, T1>, repeat TableColumn<Self, each T2>
     ),
@@ -380,13 +376,11 @@ extension Table {
   private static func _insert<
     each Value,
     each ResultColumn: QueryExpression,
-    From,
-    Joins,
     each ConflictTarget
   >(
     or conflictResolution: ConflictResolution? = nil,
     _ columns: (TableColumns) -> (repeat TableColumn<Self, each Value>),
-    select selection: () -> Select<(repeat each ResultColumn), From, Joins>,
+    select selection: () -> some PartialSelectStatement<(repeat each ResultColumn)>,
     onConflict conflictTargets: (TableColumns) -> (repeat TableColumn<Self, each ConflictTarget>)?,
     @QueryFragmentBuilder<Bool>
     where targetFilter: (TableColumns) -> [QueryFragment] = { _ in [] },

Tests/StructuredQueriesTests/InsertTests.swift

@@ -227,6 +227,31 @@ extension SnapshotTests {
         └─────────────────────┘
         """
       }
+
+      assertQuery(
+        Tag.insert {
+          $0.title
+        } select: {
+          Values("vacation")
+        }
+        .returning(\.self)
+      ) {
+        """
+        INSERT INTO "tags"
+        ("title")
+        SELECT 'vacation'
+        RETURNING "id", "title"
+        """
+      } results: {
+        """
+        ┌─────────────────────┐
+        │ Tag(                │
+        │   id: 8,            │
+        │   title: "vacation" │
+        │ )                   │
+        └─────────────────────┘
+        """
+      }
     }
 
     @Test func draft() {