ABIChecker: diagnose mangled name changes

Moving generic constraint from extension to its member or vice versa may change the mangled name
of the member without changing the generic signature, thus introducing ABI breakages. This change
teaches the ABI checker to diagnose USR (mangled name) changes to cover such cases.

rdar://78276290

Author: nkcsgexi

include/swift/AST/DiagnosticsModuleDiffer.def

@@ -88,6 +88,8 @@ ERROR(not_inheriting_convenience_inits,APIDigesterBreakage,"%0 no longer inherit
 
 ERROR(enum_case_added,APIDigesterBreakage,"%0 has been added as a new enum case", (StringRef))
 
+ERROR(demangled_name_changed,APIDigesterBreakage,"%0 has mangled name changing from '%1' to '%2'", (StringRef, StringRef, StringRef))
+
 WARNING(cannot_read_allowlist,none,"cannot read breakage allowlist at '%0'", (StringRef))
 
 #define UNDEFINE_DIAGNOSTIC_MACROS

include/swift/AST/USRGeneration.h

@@ -61,6 +61,9 @@ bool printExtensionUSR(const ExtensionDecl *ED, raw_ostream &OS);
 /// \returns true if it failed, false on success.
 bool printDeclUSR(const Decl *D, raw_ostream &OS);
 
+/// Demangle a mangle-name-based USR to a human readable name.
+std::string demangleUSR(StringRef mangled);
+
 } // namespace ide
 } // namespace swift
 

lib/APIDigester/ModuleAnalyzerNodes.cpp

@@ -944,6 +944,8 @@ static bool isSDKNodeEqual(SDKContext &Ctx, const SDKNode &L, const SDKNode &R)
         if (Left->getFixedBinaryOrder() != Right->getFixedBinaryOrder())
           return false;
       }
+      if (Left->getUsr() != Right->getUsr())
+        return false;
       LLVM_FALLTHROUGH;
     }
     case SDKNodeKind::Conformance:
@@ -2551,6 +2553,13 @@ void swift::ide::api::SDKNodeDecl::diagnose(SDKNode *Right) {
       emitDiag(Loc, diag::decl_reorder, getFixedBinaryOrder(),
                RD->getFixedBinaryOrder());
     }
+    if (getUsr() != RD->getUsr()) {
+      auto left = demangleUSR(getUsr());
+      auto right = demangleUSR(RD->getUsr());
+      if (left != right) {
+        emitDiag(Loc, diag::demangled_name_changed, left, right);
+      }
+    }
   }
 }
 

lib/APIDigester/ModuleDiagsConsumer.cpp

@@ -54,6 +54,7 @@ static StringRef getCategoryName(uint32_t ID) {
   case LocalDiagID::raw_type_change:
     return "/* RawRepresentable Changes */";
   case LocalDiagID::generic_sig_change:
+  case LocalDiagID::demangled_name_changed:
     return "/* Generic Signature Changes */";
   case LocalDiagID::enum_case_added:
   case LocalDiagID::decl_added:

lib/AST/USRGeneration.cpp

@@ -19,6 +19,7 @@
 #include "swift/AST/SwiftNameTranslation.h"
 #include "swift/AST/TypeCheckRequests.h"
 #include "swift/AST/USRGeneration.h"
+#include "swift/Demangling/Demangler.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/raw_ostream.h"
@@ -255,6 +256,18 @@ swift::USRGenerationRequest::evaluate(Evaluator &evaluator,
   return NewMangler.mangleDeclAsUSR(D, getUSRSpacePrefix());
 }
 
+std::string ide::demangleUSR(StringRef mangled) {
+  if (mangled.startswith(getUSRSpacePrefix())) {
+    mangled = mangled.substr(getUSRSpacePrefix().size());
+  }
+  SmallString<128> buffer;
+  buffer += "$s";
+  buffer += mangled;
+  mangled = buffer.str();
+  Demangler Dem;
+  return nodeToString(Dem.demangleSymbol(mangled));
+}
+
 std::string
 swift::MangleLocalTypeDeclRequest::evaluate(Evaluator &evaluator,
                                             const TypeDecl *D) const {

test/api-digester/Outputs/Cake-abi.txt

@@ -1,7 +1,17 @@
 
 /* Generic Signature Changes */
+cake: Constructor S1.init(_:) has mangled name changing from 'cake.S1.init(Swift.Int) -> cake.S1' to 'cake.S1.init(Swift.Double) -> cake.S1'
+cake: Func C1.foo1() has mangled name changing from 'static cake.C1.foo1() -> ()' to 'cake.C1.foo1() -> ()'
+cake: Func C1.foo2(_:) has mangled name changing from 'cake.C1.foo2(Swift.Int) -> ()' to 'cake.C1.foo2(() -> ()) -> ()'
 cake: Func P1.P1Constraint() has generic signature change from <Self where Self : cake.P1, Self : cake.P2> to <Self where Self : cake.P1>
+cake: Func P1.P1Constraint() has mangled name changing from '(extension in cake):cake.P1< where A: cake.P2>.P1Constraint() -> ()' to '(extension in cake):cake.P1.P1Constraint() -> ()'
+cake: Func S1.foo3() has mangled name changing from 'cake.S1.foo3() -> ()' to 'static cake.S1.foo3() -> ()'
+cake: Func S1.foo5(x:y:) has mangled name changing from 'cake.S1.foo5(x: Swift.Int, y: Swift.Int) -> ()' to 'cake.S1.foo5(x: Swift.Int, y: Swift.Int, z: Swift.Int) -> ()'
+cake: Func Somestruct2.foo1(_:) has mangled name changing from 'static cake.Somestruct2.foo1(cake.C3) -> ()' to 'static cake.NSSomestruct2.foo1(cake.C1) -> ()'
+cake: Func ownershipChange(_:_:) has mangled name changing from 'cake.ownershipChange(inout Swift.Int, __shared Swift.Int) -> ()' to 'cake.ownershipChange(Swift.Int, __owned Swift.Int) -> ()'
+cake: Func returnFunctionTypeOwnershipChange() has mangled name changing from 'cake.returnFunctionTypeOwnershipChange() -> (cake.C1) -> ()' to 'cake.returnFunctionTypeOwnershipChange() -> (__owned cake.C1) -> ()'
 cake: Protocol P3 has generic signature change from <Self : cake.P1, Self : cake.P2> to <Self : cake.P1, Self : cake.P4>
+cake: Struct Somestruct2 has mangled name changing from 'cake.Somestruct2' to 'cake.NSSomestruct2'
 
 /* RawRepresentable Changes */
 

test/api-digester/diff-demangled-name.swift

@@ -0,0 +1,21 @@
+// RUN: %empty-directory(%t)
+// RUN: echo "public func foo() {}" > %t/Foo.swift
+
+// RUN: echo "public protocol P { associatedtype A }" > %t/Foo-1.swift
+// RUN: echo "public extension P { public func f() where A == Int  {} }" >> %t/Foo-1.swift
+
+// RUN: echo "public protocol P { associatedtype A }" > %t/Foo-2.swift
+// RUN: echo "public extension P where A == Int { public func f()  {} }" >> %t/Foo-2.swift
+
+// RUN: %target-swift-frontend -emit-module %t/Foo-1.swift -module-name Foo -emit-module-interface-path %t/Foo1.swiftinterface
+// RUN: %target-swift-frontend -emit-module %t/Foo-2.swift -module-name Foo -emit-module-interface-path %t/Foo2.swiftinterface
+
+// RUN: %target-swift-frontend -compile-module-from-interface %t/Foo1.swiftinterface -o %t/Foo1.swiftmodule -module-name Foo -emit-abi-descriptor-path %t/Foo1.json
+
+// RUN: %target-swift-frontend -compile-module-from-interface %t/Foo2.swiftinterface -o %t/Foo2.swiftmodule -module-name Foo -emit-abi-descriptor-path %t/Foo2.json
+
+// RUN: %api-digester -diagnose-sdk -print-module --input-paths %t/Foo1.json -input-paths %t/Foo2.json -abi -o %t/result.txt
+
+// RUN: %FileCheck %s < %t/result.txt
+
+// CHECK: Foo: Func P.f() has mangled name changing from '(extension in Foo):Foo.P.f< where A.A == Swift.Int>() -> ()' to '(extension in Foo):Foo.P< where A.A == Swift.Int>.f() -> ()'