Sema: Restrict use of SPI operators to files importing the SPI group

Ensure that calls to SPI operators are only accepted in source files
importing the corresponding SPI group. This applies the same logic to
operators as we do for functions.

rdar://137713966

Author: xymus

lib/AST/Decl.cpp

@@ -5536,9 +5536,17 @@ static bool checkAccess(const DeclContext *useDC, const ValueDecl *VD,
     return srcPkg && usePkg && usePkg->isSamePackageAs(srcPkg);
   }
   case AccessLevel::Public:
-  case AccessLevel::Open:
+  case AccessLevel::Open: {
+    if (VD->isOperator() && VD->isSPI()) {
+      const DeclContext *useFile = useDC->getModuleScopeContext();
+      if (useFile->getParentModule() == sourceDC->getParentModule())
+        return true;
+      auto *useSF = dyn_cast<SourceFile>(useFile);
+      return !useSF || useSF->isImportedAsSPI(VD);
+    }
     return true;
   }
+  }
   llvm_unreachable("bad access level");
 }
 

test/SPI/Inputs/spi_helper.swift

@@ -4,6 +4,10 @@ public protocol PublicProto {
   associatedtype Assoc
 }
 
+public struct PublicType {
+    public init() { }
+}
+
 public func publicFunc() { print("publicFunc") }
 
 func internalFunc() {}
@@ -94,3 +98,6 @@ public enum PublicEnum {
   case publicCase
   @_spi(HelperSPI) case spiCase
 }
+
+@_spi(HelperSPI) public func -(_ s1: PublicType, _ s2: PublicType) -> PublicType { s1 }
+@_spi(HelperSPI) public func +(_ s1: PublicType, _ s2: PublicType) -> PublicType { s1 }

test/SPI/public_client.swift

@@ -40,8 +40,14 @@ otherApiFunc() // expected-error {{cannot find 'otherApiFunc' in scope}}
 public func publicUseOfSPI(param: SPIClass) -> SPIClass {} // expected-error 2{{cannot find type 'SPIClass' in scope}}
 public func publicUseOfSPI2() -> [SPIClass] {} // expected-error {{cannot find type 'SPIClass' in scope}}
 
+public let o1 = PublicType()
+public let o2 = PublicType()
+
 @inlinable
-func inlinable() -> SPIClass { // expected-error {{cannot find type 'SPIClass' in scope}}
+public func inlinable() -> SPIClass { // expected-error {{cannot find type 'SPIClass' in scope}}
   spiFunc() // expected-error {{cannot find 'spiFunc' in scope}}
   _ = SPIClass() // expected-error {{cannot find 'SPIClass' in scope}}
+  let _ = o1 - o2 // expected-error {{binary operator '-' cannot be applied to two 'PublicType' operands}}
 }
+
+let _ = o1 - o2 // expected-error {{binary operator '-' cannot be applied to two 'PublicType' operands}}

test/SPI/spi_client.swift

@@ -61,10 +61,16 @@ public func inlinable1() -> SPIClass { // expected-error {{class 'SPIClass' cann
   _ = [SPIClass]() // expected-error {{class 'SPIClass' cannot be used in an '@inlinable' function because it is an SPI imported from 'SPIHelper'}}
 }
 
+public let o1 = PublicType()
+public let o2 = PublicType()
+
 @_spi(S)
 @inlinable
 public func inlinable2() -> SPIClass {
   spiFunc()
   _ = SPIClass()
   _ = [SPIClass]()
+  let _ = o1 - o2
 }
+
+let _ = o1 - o2