swift-module-digester: diagnose let to var changes and vice versa as ABI breaking.

Author: nkcsgexi

include/swift/AST/DiagnosticsModuleDiffer.def

@@ -76,6 +76,8 @@ ERROR(nominal_type_kind_changed,none,"%0 has been changed to a %1", (StringRef,
 
 ERROR(optional_req_changed,none,"%0 is %select{now|no longer}1 an optional requirement", (StringRef, bool))
 
+ERROR(var_let_changed,none,"%0 changes from %select{var|let}1 to %select{let|var}1", (StringRef, bool))
+
 #ifndef DIAG_NO_UNDEF
 # if defined(DIAG)
 #  undef DIAG

test/api-digester/Inputs/cake1.swift

@@ -111,3 +111,6 @@ public protocol ObjCProtocol {
   @objc
   func addOptional()
 }
+
+public let GlobalLetChangedToVar = 1
+public var GlobalVarChangedToLet = 1

test/api-digester/Inputs/cake2.swift

@@ -121,3 +121,6 @@ public protocol ObjCProtocol {
   @objc
   optional func addOptional()
 }
+
+public var GlobalLetChangedToVar = 1
+public let GlobalVarChangedToLet = 1

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

@@ -13,6 +13,7 @@ cake1: Constructor fixedLayoutStruct.init(b:a:) has been removed
 cake1: Func C4.foo() has been removed
 cake1: Func RequiementChanges.removedFunc() has been removed
 cake1: Subscript RemoveSetters.subscript(_:) has removed its setter
+cake1: Var GlobalVarChangedToLet has removed its setter
 cake1: Var RemoveSetters.Value has removed its setter
 cake1: Var RequiementChanges.removedVar has been removed
 
@@ -42,6 +43,8 @@ cake1: Func S1.foo3() is now static
 cake1: Struct C6 is now with @_fixed_layout
 cake1: Var C1.CIIns1 changes from weak to strong
 cake1: Var C1.CIIns2 changes from strong to weak
+cake1: Var GlobalLetChangedToVar changes from let to var
+cake1: Var GlobalVarChangedToLet changes from var to let
 
 /* Fixed-layout Type changes */
 cake1: EnumElement FrozenKind.Fixed in a non-resilient type changes position from 1 to 2

test/api-digester/Outputs/Cake.txt

@@ -12,6 +12,7 @@ cake1: Constructor fixedLayoutStruct.init(b:a:) has been removed
 cake1: Func C4.foo() has been removed
 cake1: Func RequiementChanges.removedFunc() has been removed
 cake1: Subscript RemoveSetters.subscript(_:) has removed its setter
+cake1: Var GlobalVarChangedToLet has removed its setter
 cake1: Var RemoveSetters.Value has removed its setter
 cake1: Var RequiementChanges.removedVar has been removed
 

test/api-digester/compare-dump.swift

@@ -15,6 +15,6 @@
 // RUN: %api-digester -dump-sdk -module cake2 -o %t.dump2.json -module-cache-path %t.module-cache %clang-importer-sdk-nosource -I %t.mod -I %S/Inputs/APINotesRight -abi
 // RUN: %api-digester -diagnose-sdk -print-module --input-paths %t.dump1.json -input-paths %t.dump2.json -abi > %t.result
 
-// RUN: %clang -E -P -x c %S/Outputs/Cake-abi.txt -o - | sed '/^\s*$/d' > %t.expected
-// RUN: %clang -E -P -x c %t.result -o - | sed '/^\s*$/d' > %t.result.tmp
-// RUN: diff -u %t.expected %t.result.tmp
+// RUN: %clang -E -P -x c %S/Outputs/Cake-abi.txt -o - | sed '/^\s*$/d' > %t.abi.expected
+// RUN: %clang -E -P -x c %t.result -o - | sed '/^\s*$/d' > %t.abi.result.tmp
+// RUN: diff -u %t.abi.expected %t.abi.result.tmp

tools/swift-api-digester/ModuleAnalyzerNodes.cpp

@@ -648,6 +648,8 @@ bool SDKNode::operator==(const SDKNode &Other) const {
               if (LV->getFixedBinaryOrder() != RV->getFixedBinaryOrder())
                 return false;
             }
+            if (LV->isLet() != RV->isLet())
+              return false;
           }
         }
       }

tools/swift-api-digester/ModuleDiagsConsumer.cpp

@@ -42,6 +42,7 @@ static StringRef getCategoryName(uint32_t ID) {
     return "/* Renamed Decls */";
   case LocalDiagID::decl_attr_change:
   case LocalDiagID::decl_new_attr:
+  case LocalDiagID::var_let_changed:
     return "/* Decl Attribute changes */";
   case LocalDiagID::default_arg_removed:
   case LocalDiagID::decl_type_change:

tools/swift-api-digester/swift-api-digester.cpp

@@ -760,13 +760,19 @@ static void detectDeclChange(NodePtr L, NodePtr R, SDKContext &Ctx) {
       // Detect re-ordering if they're from structs with a fixed layout.
       auto *LV = dyn_cast<SDKNodeDeclVar>(L);
       auto *RV = dyn_cast<SDKNodeDeclVar>(R);
-      if (LV && RV &&
-          LV->hasFixedBinaryOrder() && RV->hasFixedBinaryOrder() &&
-          LV->getFixedBinaryOrder() != RV->getFixedBinaryOrder()) {
-        Ctx.getDiags().diagnose(SourceLoc(), diag::decl_reorder,
-                                LV->getScreenInfo(),
-                                LV->getFixedBinaryOrder(),
-                                RV->getFixedBinaryOrder());
+      if (LV && RV) {
+        if (LV->hasFixedBinaryOrder() && RV->hasFixedBinaryOrder() &&
+            LV->getFixedBinaryOrder() != RV->getFixedBinaryOrder()) {
+          Ctx.getDiags().diagnose(SourceLoc(), diag::decl_reorder,
+                                  LV->getScreenInfo(),
+                                  LV->getFixedBinaryOrder(),
+                                  RV->getFixedBinaryOrder());
+        }
+        if (LV->isLet() != RV->isLet()) {
+          Ctx.getDiags().diagnose(SourceLoc(), diag::var_let_changed,
+                                  LV->getScreenInfo(),
+                                  LV->isLet());
+        }
       }
     }