fix false-positive ambiguous link error, and add a regression test

Author: tayloraswift

Sources/LinkResolution/UCF.ResolutionTable.Search.swift

@@ -1,4 +1,5 @@
 import InlineArray
+import Symbols
 import UCF
 
 extension UCF.ResolutionTable
@@ -9,15 +10,15 @@ extension UCF.ResolutionTable
         let predicate:UCF.Selector.Suffix?
 
         private
-        var selected:InlineArray<Overload>
+        var selected:[Symbol.Decl: Overload]
         private
-        var rejected:[Overload]
+        var rejected:[Symbol.Decl: Overload]
 
         init(matching predicate:UCF.Selector.Suffix?)
         {
             self.predicate = predicate
-            self.selected = []
-            self.rejected = []
+            self.selected = [:]
+            self.rejected = [:]
         }
     }
 }
@@ -26,43 +27,62 @@ extension UCF.ResolutionTable.Search
     mutating
     func add(_ candidates:InlineArray<Overload>)
     {
+        //  Because of the way `@_exported` paths are represented in the search tree, it is 
+        //  possible to encounter the same overload multiple times, due to namespace inference
         if  let predicate:UCF.Selector.Suffix = self.predicate
         {
             for overload:Overload in candidates
             {
-                predicate ~= overload ?
-                self.selected.append(overload) :
-                self.rejected.append(overload)
+                guard predicate ~= overload
+                else
+                {
+                    self.rejected[overload.id] = overload
+                    continue
+                }
+
+                self.selected[overload.id] = overload
             }
         }
         else
         {
             for overload:Overload in candidates
             {
-                self.selected.append(overload)
+                self.selected[overload.id] = overload
             }
         }
     }
 
     func any() -> UCF.Resolution<Overload>?
     {
-        switch self.selected
+        guard 
+        let overload:Overload = self.selected.values.first
+        else
         {
-        case .one(let overload):
-            .overload(overload)
+            return nil 
+        }
 
-        case .some(let overloads):
-            overloads.isEmpty ? nil : .ambiguous(overloads, rejected: self.rejected)
+        if  self.selected.count == 1
+        {
+            return .overload(overload)
+        }
+        else
+        {
+            return .ambiguous(self.selected.values.sorted { $0.id < $1.id }, 
+                rejected: self.rejected.values.sorted { $0.id < $1.id })
         }
     }
 
     consuming
     func get() -> UCF.Resolution<Overload>
     {
-        switch self.selected
+        if  let overload:Overload = self.selected.values.first, self.selected.count == 1
+        {
+            return .overload(overload)
+        }
+        else
         {
-        case .one(let overload):    .overload(overload)
-        case .some(let overloads):  .ambiguous(overloads, rejected: self.rejected)
+            return .ambiguous(self.selected.values.sorted { $0.id < $1.id }, 
+                rejected: self.rejected.values.sorted { $0.id < $1.id })
         }
     }
 }

Sources/SymbolGraphBuilder/Builds/SSGC.Workspace.swift

@@ -54,17 +54,25 @@ extension SSGC.Workspace
     public
     func build(package build:SSGC.PackageBuild,
         with swift:SSGC.Toolchain,
+        validation:SSGC.ValidationBehavior = .ignoreErrors,
         clean:Bool = true) throws -> SymbolGraphObject<Void>
     {
-        try self.build(some: build, toolchain: swift, status: nil, clean: clean)
+        try self.build(some: build, toolchain: swift, 
+            status: nil, 
+            logger: .init(validation: validation, file: nil),
+            clean: clean)
     }
 
     public
     func build(special build:SSGC.StandardLibraryBuild,
         with swift:SSGC.Toolchain,
+        validation:SSGC.ValidationBehavior = .ignoreErrors,
         clean:Bool = true) throws -> SymbolGraphObject<Void>
     {
-        try self.build(some: build, toolchain: swift, status: nil, clean: clean)
+        try self.build(some: build, toolchain: swift, 
+            status: nil, 
+            logger: .init(validation: validation, file: nil),
+            clean: clean)
     }
 }
 extension SSGC.Workspace

Sources/SymbolGraphBuilderTests/Main.swift

@@ -153,6 +153,17 @@ enum Main:TestMain, TestBattery
 
         #endif
 
+        if  let tests:TestGroup = tests / "Reexportation",
+            let _:SymbolGraphObject<Void> = (tests.do
+            {
+                try workspace.build(
+                    package: .local(project: "TestPackages" / "swift-exportation"),
+                    with: toolchain,
+                    validation: .failOnErrors)
+            })
+        {
+        }
+
         group:
         if  let tests:TestGroup = tests / "Local",
             let docs:SymbolGraphObject<Void> = (tests.do

TestPackages/swift-exportation/Package.swift

@@ -0,0 +1,15 @@
+// swift-tools-version:5.10
+import PackageDescription
+
+let package:Package = .init(name: "Swift Unidoc Exportation Tests",
+    products:
+    [
+        .library(name: "A", targets: ["A"]),
+        .library(name: "B", targets: ["B"]),
+    ],
+    targets:
+    [
+        .target(name: "_A"),
+        .target(name: "A", dependencies: ["_A"]),
+        .target(name: "B", dependencies: ["A"]),
+    ])

TestPackages/swift-exportation/Sources/A/exports.swift

@@ -0,0 +1 @@
+@_exported import _A

TestPackages/swift-exportation/Sources/B/anchor.swift

@@ -0,0 +1,7 @@
+# Exportation tests 
+
+All of the following should be valid links:
+
+-  ``A``
+-  ``A.A``
+-  ``_A.A``

TestPackages/swift-exportation/Sources/B/docs.docc/Article.md

@@ -0,0 +1,4 @@
+public
+enum A 
+{
+}