diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 21707940a5a..bb866c6b8cb 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -4730,13 +4730,16 @@ module ts {
             if (!inferredType) {
                 let inferences = getInferenceCandidates(context, index);
                 if (inferences.length) {
-                    // Infer widened union or supertype, or the undefined type for no common supertype
+                    // Infer widened union or supertype, or the unknown type for no common supertype
                     let unionOrSuperType = context.inferUnionTypes ? getUnionType(inferences) : getCommonSupertype(inferences);
                     inferredType = unionOrSuperType ? getWidenedType(unionOrSuperType) : unknownType;
                     inferenceSucceeded = !!unionOrSuperType;
                 }
                 else {
-                    // Infer the empty object type when no inferences were made
+                    // Infer the empty object type when no inferences were made. It is important to remember that
+                    // in this case, inference still succeeds, meaning there is no error for not having inference
+                    // candidates. An inference error only occurs when there are *conflicting* candidates, i.e.
+                    // candidates with no common supertype.
                     inferredType = emptyObjectType;
                     inferenceSucceeded = true;
                 }
@@ -4746,10 +4749,10 @@ module ts {
                     let constraint = getConstraintOfTypeParameter(context.typeParameters[index]);
                     inferredType = constraint && !isTypeAssignableTo(inferredType, constraint) ? constraint : inferredType;
                 }
-                // If inference failed, it is necessary to record the index of the failed type parameter (the one we are on).
-                // It might be that inference has already failed on a later type parameter on a previous call to inferTypeArguments.
-                // So if this failure is on preceding type parameter, this type parameter is the new failure index.
                 else if (context.failedTypeParameterIndex === undefined || context.failedTypeParameterIndex > index) {
+                    // If inference failed, it is necessary to record the index of the failed type parameter (the one we are on).
+                    // It might be that inference has already failed on a later type parameter on a previous call to inferTypeArguments.
+                    // So if this failure is on preceding type parameter, this type parameter is the new failure index.
                     context.failedTypeParameterIndex = index;
                 }
                 context.inferredTypes[index] = inferredType;
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 5880dfdce92..403c96b239b 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -1482,6 +1482,7 @@ module ts {
         (t: Type): Type;
     }
 
+    // @internal
     export interface TypeInferences {
         primary: Type[];    // Inferences made directly to a type parameter
         secondary: Type[];  // Inferences made to a type parameter in a union type
@@ -1489,6 +1490,7 @@ module ts {
                             // If a type parameter is fixed, no more inferences can be made for the type parameter
     }
 
+    // @internal
     export interface InferenceContext {
         typeParameters: TypeParameter[];    // Type parameters for which inferences are made
         inferUnionTypes: boolean;           // Infer union types for disjoint candidates (otherwise undefinedType)
diff --git a/tests/baselines/reference/APISample_compile.js b/tests/baselines/reference/APISample_compile.js
index d08d0b3fcc2..e2c0341d5dd 100644
--- a/tests/baselines/reference/APISample_compile.js
+++ b/tests/baselines/reference/APISample_compile.js
@@ -1172,18 +1172,6 @@ declare module "typescript" {
     interface TypeMapper {
         (t: Type): Type;
     }
-    interface TypeInferences {
-        primary: Type[];
-        secondary: Type[];
-        isFixed: boolean;
-    }
-    interface InferenceContext {
-        typeParameters: TypeParameter[];
-        inferUnionTypes: boolean;
-        inferences: TypeInferences[];
-        inferredTypes: Type[];
-        failedTypeParameterIndex?: number;
-    }
     interface DiagnosticMessage {
         key: string;
         category: DiagnosticCategory;
diff --git a/tests/baselines/reference/APISample_compile.types b/tests/baselines/reference/APISample_compile.types
index df0c57444b0..12803044f6e 100644
--- a/tests/baselines/reference/APISample_compile.types
+++ b/tests/baselines/reference/APISample_compile.types
@@ -3756,41 +3756,6 @@ declare module "typescript" {
 >t : Type
 >Type : Type
 >Type : Type
-    }

-    interface TypeInferences {

->TypeInferences : TypeInferences
-
-        primary: Type[];

->primary : Type[]
->Type : Type
-
-        secondary: Type[];

->secondary : Type[]
->Type : Type
-
-        isFixed: boolean;

->isFixed : boolean
-    }

-    interface InferenceContext {

->InferenceContext : InferenceContext
-
-        typeParameters: TypeParameter[];

->typeParameters : TypeParameter[]
->TypeParameter : TypeParameter
-
-        inferUnionTypes: boolean;

->inferUnionTypes : boolean
-
-        inferences: TypeInferences[];

->inferences : TypeInferences[]
->TypeInferences : TypeInferences
-
-        inferredTypes: Type[];

->inferredTypes : Type[]
->Type : Type
-
-        failedTypeParameterIndex?: number;

->failedTypeParameterIndex : number
     }

     interface DiagnosticMessage {

 >DiagnosticMessage : DiagnosticMessage
diff --git a/tests/baselines/reference/APISample_linter.js b/tests/baselines/reference/APISample_linter.js
index fb390d78f8f..265d84ac5b3 100644
--- a/tests/baselines/reference/APISample_linter.js
+++ b/tests/baselines/reference/APISample_linter.js
@@ -1203,18 +1203,6 @@ declare module "typescript" {
     interface TypeMapper {
         (t: Type): Type;
     }
-    interface TypeInferences {
-        primary: Type[];
-        secondary: Type[];
-        isFixed: boolean;
-    }
-    interface InferenceContext {
-        typeParameters: TypeParameter[];
-        inferUnionTypes: boolean;
-        inferences: TypeInferences[];
-        inferredTypes: Type[];
-        failedTypeParameterIndex?: number;
-    }
     interface DiagnosticMessage {
         key: string;
         category: DiagnosticCategory;
diff --git a/tests/baselines/reference/APISample_linter.types b/tests/baselines/reference/APISample_linter.types
index 90360b5fe61..f818edbaf39 100644
--- a/tests/baselines/reference/APISample_linter.types
+++ b/tests/baselines/reference/APISample_linter.types
@@ -3902,41 +3902,6 @@ declare module "typescript" {
 >t : Type
 >Type : Type
 >Type : Type
-    }

-    interface TypeInferences {

->TypeInferences : TypeInferences
-
-        primary: Type[];

->primary : Type[]
->Type : Type
-
-        secondary: Type[];

->secondary : Type[]
->Type : Type
-
-        isFixed: boolean;

->isFixed : boolean
-    }

-    interface InferenceContext {

->InferenceContext : InferenceContext
-
-        typeParameters: TypeParameter[];

->typeParameters : TypeParameter[]
->TypeParameter : TypeParameter
-
-        inferUnionTypes: boolean;

->inferUnionTypes : boolean
-
-        inferences: TypeInferences[];

->inferences : TypeInferences[]
->TypeInferences : TypeInferences
-
-        inferredTypes: Type[];

->inferredTypes : Type[]
->Type : Type
-
-        failedTypeParameterIndex?: number;

->failedTypeParameterIndex : number
     }

     interface DiagnosticMessage {

 >DiagnosticMessage : DiagnosticMessage
diff --git a/tests/baselines/reference/APISample_transform.js b/tests/baselines/reference/APISample_transform.js
index 96b54ccd917..f1da0e2533a 100644
--- a/tests/baselines/reference/APISample_transform.js
+++ b/tests/baselines/reference/APISample_transform.js
@@ -1204,18 +1204,6 @@ declare module "typescript" {
     interface TypeMapper {
         (t: Type): Type;
     }
-    interface TypeInferences {
-        primary: Type[];
-        secondary: Type[];
-        isFixed: boolean;
-    }
-    interface InferenceContext {
-        typeParameters: TypeParameter[];
-        inferUnionTypes: boolean;
-        inferences: TypeInferences[];
-        inferredTypes: Type[];
-        failedTypeParameterIndex?: number;
-    }
     interface DiagnosticMessage {
         key: string;
         category: DiagnosticCategory;
diff --git a/tests/baselines/reference/APISample_transform.types b/tests/baselines/reference/APISample_transform.types
index 999c81af401..6f22fb1ec6a 100644
--- a/tests/baselines/reference/APISample_transform.types
+++ b/tests/baselines/reference/APISample_transform.types
@@ -3852,41 +3852,6 @@ declare module "typescript" {
 >t : Type
 >Type : Type
 >Type : Type
-    }

-    interface TypeInferences {

->TypeInferences : TypeInferences
-
-        primary: Type[];

->primary : Type[]
->Type : Type
-
-        secondary: Type[];

->secondary : Type[]
->Type : Type
-
-        isFixed: boolean;

->isFixed : boolean
-    }

-    interface InferenceContext {

->InferenceContext : InferenceContext
-
-        typeParameters: TypeParameter[];

->typeParameters : TypeParameter[]
->TypeParameter : TypeParameter
-
-        inferUnionTypes: boolean;

->inferUnionTypes : boolean
-
-        inferences: TypeInferences[];

->inferences : TypeInferences[]
->TypeInferences : TypeInferences
-
-        inferredTypes: Type[];

->inferredTypes : Type[]
->Type : Type
-
-        failedTypeParameterIndex?: number;

->failedTypeParameterIndex : number
     }

     interface DiagnosticMessage {

 >DiagnosticMessage : DiagnosticMessage
diff --git a/tests/baselines/reference/APISample_watcher.js b/tests/baselines/reference/APISample_watcher.js
index 8a3d2065a23..734467a1c59 100644
--- a/tests/baselines/reference/APISample_watcher.js
+++ b/tests/baselines/reference/APISample_watcher.js
@@ -1241,18 +1241,6 @@ declare module "typescript" {
     interface TypeMapper {
         (t: Type): Type;
     }
-    interface TypeInferences {
-        primary: Type[];
-        secondary: Type[];
-        isFixed: boolean;
-    }
-    interface InferenceContext {
-        typeParameters: TypeParameter[];
-        inferUnionTypes: boolean;
-        inferences: TypeInferences[];
-        inferredTypes: Type[];
-        failedTypeParameterIndex?: number;
-    }
     interface DiagnosticMessage {
         key: string;
         category: DiagnosticCategory;
diff --git a/tests/baselines/reference/APISample_watcher.types b/tests/baselines/reference/APISample_watcher.types
index f66c818c53d..37940e9a1f8 100644
--- a/tests/baselines/reference/APISample_watcher.types
+++ b/tests/baselines/reference/APISample_watcher.types
@@ -4025,41 +4025,6 @@ declare module "typescript" {
 >t : Type
 >Type : Type
 >Type : Type
-    }

-    interface TypeInferences {

->TypeInferences : TypeInferences
-
-        primary: Type[];

->primary : Type[]
->Type : Type
-
-        secondary: Type[];

->secondary : Type[]
->Type : Type
-
-        isFixed: boolean;

->isFixed : boolean
-    }

-    interface InferenceContext {

->InferenceContext : InferenceContext
-
-        typeParameters: TypeParameter[];

->typeParameters : TypeParameter[]
->TypeParameter : TypeParameter
-
-        inferUnionTypes: boolean;

->inferUnionTypes : boolean
-
-        inferences: TypeInferences[];

->inferences : TypeInferences[]
->TypeInferences : TypeInferences
-
-        inferredTypes: Type[];

->inferredTypes : Type[]
->Type : Type
-
-        failedTypeParameterIndex?: number;

->failedTypeParameterIndex : number
     }

     interface DiagnosticMessage {

 >DiagnosticMessage : DiagnosticMessage