Merge pull request #19564 from nkcsgexi/remove-alias-abi

swift-module-digester: exclude TypeAliasDecl entirely when checking ABI stability.

Author: nkcsgexi

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

@@ -7,6 +7,7 @@ cake1: Protocol P3 has generic signature change from <τ_0_0 : P1, τ_0_0 : P2>
 
 /* Removed Decls */
 cake1: AssociatedType RequiementChanges.removedType has been removed
+cake1: Class C3 has been removed
 cake1: Constructor Somestruct2.init(_:) has been removed
 cake1: Constructor fixedLayoutStruct.init(b:a:) has been removed
 cake1: Func C4.foo() has been removed

test/api-digester/Outputs/cake-abi.json

@@ -503,24 +503,6 @@
             }
           ]
         },
-        {
-          "kind": "TypeAlias",
-          "name": "RawValue",
-          "printedName": "RawValue",
-          "declKind": "TypeAlias",
-          "usr": "s:4cake6NumberO8RawValuea",
-          "location": "",
-          "moduleName": "cake",
-          "implicit": true,
-          "children": [
-            {
-              "kind": "TypeNominal",
-              "name": "Int",
-              "printedName": "Int",
-              "usr": "s:Si"
-            }
-          ]
-        },
         {
           "kind": "Var",
           "name": "hashValue",
@@ -1001,24 +983,6 @@
               ]
             }
           ]
-        },
-        {
-          "kind": "TypeAlias",
-          "name": "NonReqAlias",
-          "printedName": "NonReqAlias",
-          "declKind": "TypeAlias",
-          "usr": "s:4cake21ProWithAssociatedTypePAAE11NonReqAliasa",
-          "location": "",
-          "moduleName": "cake",
-          "genericSig": "<τ_0_0 where τ_0_0 : ProWithAssociatedType>",
-          "children": [
-            {
-              "kind": "TypeNominal",
-              "name": "Int",
-              "printedName": "Int",
-              "usr": "s:Si"
-            }
-          ]
         }
       ]
     },

tools/swift-api-digester/ModuleAnalyzerNodes.cpp

@@ -1158,6 +1158,10 @@ SwiftDeclCollector::shouldIgnore(Decl *D, const Decl* Parent) {
       return true;
     if (VD->getBaseName().empty())
       return true;
+
+    // Exclude type alias decls because they should have no impact on ABI.
+    if (isa<TypeAliasDecl>(VD) && Ctx.checkingABI())
+      return true;
     switch (VD->getFormalAccess()) {
     case AccessLevel::Internal:
     case AccessLevel::Private: