Remove duplicate HEADER_SEARCH_PATHS (#787)

- In the even two library dependencies shared the same `publicHeaders` path (e.g. `libcrypto.a` and `libssl.a` in OpenSSL) duplicate entries were added to the `HEADER_SEARCH_PATHS` build setting
- This was regressed due to an earlier change #751
  - previously the uniquing was happening in the settings helper when build settings were extended multiple times
- To resolve this, we now ensure we unique paths being added
- Additionally a test is included to ensure this doesn't regress in the future

Test Plan:

- Verify the unit tests pass

A bit of a contrived manual test case

update the fixture in `fixtures/ios_app_with_static_libraries/Modules/A/Project.swift`

```swift
let project = Project(name: "A",
                      targets: [
                          Target(name: "A",
                                 platform: .iOS,
                                 product: .staticLibrary,
                                 bundleId: "io.tuist.A",
                                 infoPlist: "Info.plist",
                                 sources: "Sources/**",
                                 dependencies: [
                                     .project(target: "B", path: "../B"),
                                     .library(path: "../C/prebuilt/C/libC.a",
                                             publicHeaders: "../C/prebuilt/C",
                                             swiftModuleMap: "../C/prebuilt/C/C.swiftmodule"),
                                    // Add a duplicate
                                     .library(path: "../C/prebuilt/C/libC.a",
                                             publicHeaders: "../C/prebuilt/C",
                                             swiftModuleMap: "../C/prebuilt/C/C.swiftmodule")
                          ])
])
```

This of course causes a duplicate binary (hence why it wasn't included) but can help illustrate a situation where two `.library` dependencies point to the same `publicHeaders` path.

CHANGELOG.md

@@ -40,6 +40,7 @@ Please, check out guidelines: https://keepachangelog.com/en/1.0.0/
 ### Fixed
 
 - Ensure custom search path settings are included in generated projects https://github.com/tuist/tuist/pull/751 by @kwridan
+- Remove duplicate HEADER_SEARCH_PATHS https://github.com/tuist/tuist/pull/787 by @kwridan
 
 ## 0.19.0
 

Sources/TuistGenerator/Generator/LinkGenerator.swift

@@ -256,7 +256,7 @@ final class LinkGenerator: LinkGenerating {
             return
         }
         let value = SettingValue
-            .array(["$(inherited)"] + paths.sorted()
+            .array(["$(inherited)"] + paths.uniqued().sorted()
                 .map { $0.relative(to: sourceRootPath).pathString }
                 .map { "$(SRCROOT)/\($0)" })
         let newSetting = [name: value]

Tests/TuistGeneratorTests/Generator/LinkGeneratorTests.swift

@@ -88,7 +88,7 @@ final class LinkGeneratorErrorTests: XCTestCase {
             XCTAssertEqual($0 as? LinkGeneratorError, LinkGeneratorError.missingProduct(name: "Test"))
         }
     }
-    
+
     func test_generateEmbedPhase_setupEmbedFrameworksBuildPhase_whenXCFrameworkIsPresent() throws {
         // Given
         var dependencies: [GraphDependencyReference] = []
@@ -114,9 +114,9 @@ final class LinkGeneratorErrorTests: XCTestCase {
         let copyBuildPhase = try XCTUnwrap(pbxTarget.embedFrameworksBuildPhases().first)
         XCTAssertEqual(copyBuildPhase.name, "Embed Frameworks")
         let buildFiles = try XCTUnwrap(copyBuildPhase.files)
-        XCTAssertEqual(buildFiles.map { $0.file?.path }, [ "Test.xcframework"])
+        XCTAssertEqual(buildFiles.map { $0.file?.path }, ["Test.xcframework"])
         XCTAssertEqual(buildFiles.map { $0.settings as? [String: [String]] }, [
-            ["ATTRIBUTES": ["CodeSignOnCopy"]]
+            ["ATTRIBUTES": ["CodeSignOnCopy"]],
         ])
     }
 
@@ -200,6 +200,29 @@ final class LinkGeneratorErrorTests: XCTestCase {
         ])
     }
 
+    func test_setupHeadersSearchPaths_mergesDuplicates() throws {
+        // Given
+        let searchPaths = [
+            AbsolutePath("/path/to/libraries"),
+            AbsolutePath("/path/to/libraries"),
+            AbsolutePath("/path/to/libraries"),
+        ]
+        let sourceRootPath = AbsolutePath("/path")
+        let xcodeprojElements = createXcodeprojElements()
+
+        // When
+        try subject.setupHeadersSearchPath(searchPaths,
+                                           pbxTarget: xcodeprojElements.pbxTarget,
+                                           sourceRootPath: sourceRootPath)
+
+        // Then
+        let config = xcodeprojElements.config
+        XCTAssertEqual(config.buildSettings["HEADER_SEARCH_PATHS"] as? [String], [
+            "$(inherited)",
+            "$(SRCROOT)/to/libraries",
+        ])
+    }
+
     func test_setupHeadersSearchPath_throws_whenTheConfigurationListIsMissing() throws {
         let headersFolders = [AbsolutePath("/headers")]
         let pbxproj = PBXProj()
@@ -513,7 +536,7 @@ final class LinkGeneratorErrorTests: XCTestCase {
 
         return projectFileElements
     }
-    
+
     private func createFileElements(fileAbsolutePath: AbsolutePath) -> ProjectFileElements {
         let fileElements = ProjectFileElements()
         fileElements.elements[fileAbsolutePath] = PBXFileReference(path: fileAbsolutePath.basename)