TBDGen: Introduce SymbolSource::getDecl() and adopt it.

By adopting this new utility, swift-api-extract more reliably gets the
ValueDecl associated with a symbol and therefore reports more accurate
availability info.

Author: tshortli

include/swift/AST/TBDGenRequests.h

@@ -222,6 +222,26 @@ class SymbolSource {
     return irEntity;
   }
 
+  /// Returns the associated decl.
+  const ValueDecl *getDecl() const {
+    switch (kind) {
+    case Kind::SIL: {
+      if (silDeclRef.hasDecl())
+        return silDeclRef.getDecl();
+      return nullptr;
+    }
+    case Kind::Global:
+      return Global;
+    case Kind::IR:
+      if (irEntity.hasDecl())
+        return irEntity.getDecl();
+      return nullptr;
+    case Kind::LinkerDirective:
+    case Kind::Unknown:
+      return nullptr;
+    }
+  }
+
   /// Typecheck the entity wrapped by this `SymbolSource`
   void typecheck() const {
     switch (kind) {

lib/IRGen/TBDGen.cpp

@@ -674,19 +674,11 @@ class APIGenRecorder final : public APIRecorder {
 
     apigen::APIAvailability availability;
     auto access = apigen::APIAccess::Public;
-    if (source.kind == SymbolSource::Kind::SIL) {
-      auto ref = source.getSILDeclRef();
-      if (ref.hasDecl()) {
-        availability = getAvailability(ref.getDecl());
-        if (isSPI(ref.getDecl()))
-          access = apigen::APIAccess::Private;
-      }
-    } else if (source.kind == SymbolSource::Kind::IR) {
-      auto ref = source.getIRLinkEntity();
-      if (ref.hasDecl()) {
-        if (isSPI(ref.getDecl()))
-          access = apigen::APIAccess::Private;
-      }
+    auto decl = source.getDecl();
+    if (decl) {
+      availability = getAvailability(decl);
+      if (isSPI(decl))
+        access = apigen::APIAccess::Private;
     }
 
     api.addSymbol(symbol, moduleLoc, apigen::APILinkage::Exported,

test/APIJSON/apigen.swift

@@ -146,19 +146,22 @@ public var myGlobalVar: Int = 42
 // CHECK-NEXT:     "name": "_$s8MyModule4TestCMn",
 // CHECK-NEXT:     "access": "public",
 // CHECK-NEXT:     "file": "/@input/MyModule.swiftinterface",
-// CHECK-NEXT:     "linkage": "exported"
+// CHECK-NEXT:     "linkage": "exported",
+// CHECK-NEXT:     "introduced": "10.13"
 // CHECK-NEXT:   },
 // CHECK-NEXT:   {
 // CHECK-NEXT:     "name": "_$s8MyModule4TestCMo",
 // CHECK-NEXT:     "access": "public",
 // CHECK-NEXT:     "file": "/@input/MyModule.swiftinterface",
-// CHECK-NEXT:     "linkage": "exported"
+// CHECK-NEXT:     "linkage": "exported",
+// CHECK-NEXT:     "introduced": "10.13"
 // CHECK-NEXT:   },
 // CHECK-NEXT:   {
 // CHECK-NEXT:     "name": "_$s8MyModule4TestCMu",
 // CHECK-NEXT:     "access": "public",
 // CHECK-NEXT:     "file": "/@input/MyModule.swiftinterface",
-// CHECK-NEXT:     "linkage": "exported"
+// CHECK-NEXT:     "linkage": "exported",
+// CHECK-NEXT:     "introduced": "10.13"
 // CHECK-NEXT:   },
 // CHECK-NEXT:   {
 // CHECK-NEXT:     "name": "_$s8MyModule4TestCN",
@@ -320,13 +323,15 @@ public var myGlobalVar: Int = 42
 // CHECK-NEXT:     "name": "_$s8MyModule7DerivedCMn",
 // CHECK-NEXT:     "access": "public",
 // CHECK-NEXT:     "file": "/@input/MyModule.swiftinterface",
-// CHECK-NEXT:     "linkage": "exported"
+// CHECK-NEXT:     "linkage": "exported",
+// CHECK-NEXT:     "introduced": "10.13"
 // CHECK-NEXT:   },
 // CHECK-NEXT:   {
 // CHECK-NEXT:     "name": "_$s8MyModule7DerivedCMo",
 // CHECK-NEXT:     "access": "public",
 // CHECK-NEXT:     "file": "/@input/MyModule.swiftinterface",
-// CHECK-NEXT:     "linkage": "exported"
+// CHECK-NEXT:     "linkage": "exported",
+// CHECK-NEXT:     "introduced": "10.13"
 // CHECK-NEXT:   },
 // CHECK-NEXT:   {
 // CHECK-NEXT:     "name": "_$s8MyModule7DerivedCN",

test/APIJSON/spi.swift

@@ -33,13 +33,15 @@ public func spiAvailableFunc() {}
 // CHECK-NEXT:       "name": "_$s8MyModule0A6Class2C18spiAvailableMethodyyFTj",
 // CHECK-NEXT:       "access": "public",
 // CHECK-NEXT:       "file": "/@input/MyModule.swiftinterface",
-// CHECK-NEXT:       "linkage": "exported"
+// CHECK-NEXT:       "linkage": "exported",
+// CHECK-NEXT:       "unavailable": true
 // CHECK-NEXT:     },
 // CHECK-NEXT:     {
 // CHECK-NEXT:       "name": "_$s8MyModule0A6Class2C18spiAvailableMethodyyFTq",
 // CHECK-NEXT:       "access": "public",
 // CHECK-NEXT:       "file": "/@input/MyModule.swiftinterface",
-// CHECK-NEXT:       "linkage": "exported"
+// CHECK-NEXT:       "linkage": "exported",
+// CHECK-NEXT:       "unavailable": true
 // CHECK-NEXT:     },
 // CHECK-NEXT:     {
 // CHECK-NEXT:       "name": "_$s8MyModule0A6Class2CACycfC",
@@ -191,13 +193,15 @@ public func spiAvailableFunc() {}
 // CHECK-SPI-NEXT:       "name": "_$s8MyModule0A6Class2C18spiAvailableMethodyyFTj",
 // CHECK-SPI-NEXT:       "access": "private",
 // CHECK-SPI-NEXT:       "file": "/@input/MyModule.swiftmodule",
-// CHECK-SPI-NEXT:       "linkage": "exported"
+// CHECK-SPI-NEXT:       "linkage": "exported",
+// CHECK-SPI-NEXT:       "introduced": "10.10"
 // CHECK-SPI-NEXT:     },
 // CHECK-SPI-NEXT:     {
 // CHECK-SPI-NEXT:       "name": "_$s8MyModule0A6Class2C18spiAvailableMethodyyFTq",
 // CHECK-SPI-NEXT:       "access": "private",
 // CHECK-SPI-NEXT:       "file": "/@input/MyModule.swiftmodule",
-// CHECK-SPI-NEXT:       "linkage": "exported"
+// CHECK-SPI-NEXT:       "linkage": "exported",
+// CHECK-SPI-NEXT:       "introduced": "10.10"
 // CHECK-SPI-NEXT:     },
 // CHECK-SPI-NEXT:     {
 // CHECK-SPI-NEXT:       "name": "_$s8MyModule0A6Class2C9spiMethodyyFTj",

test/APIJSON/struct.swift

@@ -39,7 +39,8 @@ public struct TestStruct {
 // CHECK-NEXT:       "name": "_$s8MyModule10TestStructVMn",
 // CHECK-NEXT:       "access": "public",
 // CHECK-NEXT:       "file": "/@input/MyModule.swiftinterface",
-// CHECK-NEXT:       "linkage": "exported"
+// CHECK-NEXT:       "linkage": "exported",
+// CHECK-NEXT:       "introduced": "10.13"
 // CHECK-NEXT:     },
 // CHECK-NEXT:     {
 // CHECK-NEXT:       "name": "_$s8MyModule10TestStructVN",