Remove overeager CHECK. (#4159)

When evaluating within the context of a specific, we can encounter uses
of bindings that are nested within that specific, for example parts of
the declaration of a nested generic. Those bindings should evaluate to
the canonical form of themselves, as they would when evaluating outside
the context of the specific.

Fixes #4157.

toolchain/check/eval.cpp

@@ -1335,13 +1335,9 @@ auto TryEvalInstInContext(EvalContext& eval_context, SemIR::InstId inst_id,
         const auto& specific =
             eval_context.generic_instances().Get(eval_context.specific_id);
         auto args = eval_context.inst_blocks().Get(specific.args_id);
-        if (static_cast<size_t>(bind_name.bind_index.index) >= args.size()) {
-          // TODO: For now we don't provide a mapping for the `Self` type in an
-          // interface, and fall back to the canonical constant type.
-          CARBON_CHECK(bind_name.name_id == SemIR::NameId::SelfType)
-              << "Use of binding " << bind_name.bind_index
-              << " with no corresponding value.";
-        } else {
+        // Bindings past the ones with known arguments can appear as local
+        // bindings of entities declared within this generic.
+        if (static_cast<size_t>(bind_name.bind_index.index) < args.size()) {
           return eval_context.context.constant_values().Get(
               args[bind_name.bind_index.index]);
         }

toolchain/check/testdata/class/generic/call.carbon

@@ -63,6 +63,25 @@ class Class(T:! type, N:! i32) {}
 // CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 var a: Class(5, i32*);
 
+// --- call_in_nested_return_type.carbon
+
+class Outer(T:! type) {
+  class Inner(U:! type) {
+    fn A() -> Outer(T) {
+      return {};
+    }
+    fn B() -> Outer(U) {
+      return {};
+    }
+    fn C() -> Inner(T) {
+      return {};
+    }
+    fn D() -> Inner(U) {
+      return {};
+    }
+  }
+}
+
 // CHECK:STDOUT: --- call.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
@@ -403,3 +422,248 @@ var a: Class(5, i32*);
 // CHECK:STDOUT:   %N => constants.%N
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
+// CHECK:STDOUT: --- call_in_nested_return_type.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %T: type = bind_symbolic_name T 0 [symbolic]
+// CHECK:STDOUT:   %Outer.type: type = generic_class_type @Outer [template]
+// CHECK:STDOUT:   %.1: type = tuple_type () [template]
+// CHECK:STDOUT:   %Outer.1: %Outer.type = struct_value () [template]
+// CHECK:STDOUT:   %Outer.2: type = class_type @Outer, @Outer(%T) [symbolic]
+// CHECK:STDOUT:   %U: type = bind_symbolic_name U 1 [symbolic]
+// CHECK:STDOUT:   %Inner.type: type = generic_class_type @Inner [template]
+// CHECK:STDOUT:   %Inner.1: %Inner.type = struct_value () [template]
+// CHECK:STDOUT:   %Inner.2: type = class_type @Inner, @Inner(%T, %U) [symbolic]
+// CHECK:STDOUT:   %A.type: type = fn_type @A [template]
+// CHECK:STDOUT:   %A: %A.type = struct_value () [template]
+// CHECK:STDOUT:   %Outer.3: type = class_type @Outer, @Outer(%U) [symbolic]
+// CHECK:STDOUT:   %B.type: type = fn_type @B [template]
+// CHECK:STDOUT:   %B: %B.type = struct_value () [template]
+// CHECK:STDOUT:   %Inner.3: type = class_type @Inner, @Inner(%T) [symbolic]
+// CHECK:STDOUT:   %C.type: type = fn_type @C [template]
+// CHECK:STDOUT:   %C: %C.type = struct_value () [template]
+// CHECK:STDOUT:   %Inner.4: type = class_type @Inner, @Inner(%U) [symbolic]
+// CHECK:STDOUT:   %D.type: type = fn_type @D [template]
+// CHECK:STDOUT:   %D: %D.type = struct_value () [template]
+// CHECK:STDOUT:   %.2: type = struct_type {} [template]
+// CHECK:STDOUT:   %.3: type = ptr_type %.2 [template]
+// CHECK:STDOUT:   %struct.1: %Outer.2 = struct_value () [symbolic]
+// CHECK:STDOUT:   %struct.2: %Outer.3 = struct_value () [symbolic]
+// CHECK:STDOUT:   %struct.3: %Inner.3 = struct_value () [symbolic]
+// CHECK:STDOUT:   %struct.4: %Inner.4 = struct_value () [symbolic]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   package: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .Core = %Core
+// CHECK:STDOUT:     .Outer = %Outer.decl
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import = import Core
+// CHECK:STDOUT:   %Core: <namespace> = namespace %Core.import, [template] {
+// CHECK:STDOUT:     import Core//prelude
+// CHECK:STDOUT:     import Core//prelude/operators
+// CHECK:STDOUT:     import Core//prelude/types
+// CHECK:STDOUT:     import Core//prelude/operators/arithmetic
+// CHECK:STDOUT:     import Core//prelude/operators/bitwise
+// CHECK:STDOUT:     import Core//prelude/operators/comparison
+// CHECK:STDOUT:     import Core//prelude/types/bool
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Outer.decl: %Outer.type = class_decl @Outer [template = constants.%Outer.1] {
+// CHECK:STDOUT:     %T.loc2_13.1: type = param T
+// CHECK:STDOUT:     %T.loc2_13.2: type = bind_symbolic_name T 0, %T.loc2_13.1 [symbolic = @Outer.%T (constants.%T)]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic class @Outer(file.%T.loc2_13.2: type) {
+// CHECK:STDOUT:   %T: type = bind_symbolic_name T 0 [symbolic = %T (constants.%T)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:
+// CHECK:STDOUT:   class {
+// CHECK:STDOUT:     %Inner.decl: %Inner.type = class_decl @Inner [template = constants.%Inner.1] {
+// CHECK:STDOUT:       %U.loc3_15.1: type = param U
+// CHECK:STDOUT:       %U.loc3_15.2: type = bind_symbolic_name U 1, %U.loc3_15.1 [symbolic = @Inner.%U (constants.%U)]
+// CHECK:STDOUT:     }
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !members:
+// CHECK:STDOUT:     .Self = constants.%Outer.2
+// CHECK:STDOUT:     .Inner = %Inner.decl
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic class @Inner(file.%T.loc2_13.2: type, @Outer.%U.loc3_15.2: type) {
+// CHECK:STDOUT:   %U: type = bind_symbolic_name U 1 [symbolic = %U (constants.%U)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:
+// CHECK:STDOUT:   class {
+// CHECK:STDOUT:     %A.decl: %A.type = fn_decl @A [template = constants.%A] {
+// CHECK:STDOUT:       %Outer.ref.loc4: %Outer.type = name_ref Outer, file.%Outer.decl [template = constants.%Outer.1]
+// CHECK:STDOUT:       %T.ref.loc4: type = name_ref T, file.%T.loc2_13.2 [symbolic = @A.%T (constants.%T)]
+// CHECK:STDOUT:       %.loc4_20: init type = call %Outer.ref.loc4(%T.ref.loc4) [symbolic = @A.%Outer (constants.%Outer.2)]
+// CHECK:STDOUT:       %.loc4_22.1: type = value_of_initializer %.loc4_20 [symbolic = @A.%Outer (constants.%Outer.2)]
+// CHECK:STDOUT:       %.loc4_22.2: type = converted %.loc4_20, %.loc4_22.1 [symbolic = @A.%Outer (constants.%Outer.2)]
+// CHECK:STDOUT:       %return.var.loc4: ref %Outer.2 = var <return slot>
+// CHECK:STDOUT:     }
+// CHECK:STDOUT:     %B.decl: %B.type = fn_decl @B [template = constants.%B] {
+// CHECK:STDOUT:       %Outer.ref.loc7: %Outer.type = name_ref Outer, file.%Outer.decl [template = constants.%Outer.1]
+// CHECK:STDOUT:       %U.ref.loc7: type = name_ref U, @Outer.%U.loc3_15.2 [symbolic = @B.%U (constants.%U)]
+// CHECK:STDOUT:       %.loc7_20: init type = call %Outer.ref.loc7(%U.ref.loc7) [symbolic = @B.%Outer (constants.%Outer.3)]
+// CHECK:STDOUT:       %.loc7_22.1: type = value_of_initializer %.loc7_20 [symbolic = @B.%Outer (constants.%Outer.3)]
+// CHECK:STDOUT:       %.loc7_22.2: type = converted %.loc7_20, %.loc7_22.1 [symbolic = @B.%Outer (constants.%Outer.3)]
+// CHECK:STDOUT:       %return.var.loc7: ref %Outer.3 = var <return slot>
+// CHECK:STDOUT:     }
+// CHECK:STDOUT:     %C.decl: %C.type = fn_decl @C [template = constants.%C] {
+// CHECK:STDOUT:       %Inner.ref.loc10: %Inner.type = name_ref Inner, @Outer.%Inner.decl [template = constants.%Inner.1]
+// CHECK:STDOUT:       %T.ref.loc10: type = name_ref T, file.%T.loc2_13.2 [symbolic = @C.%T (constants.%T)]
+// CHECK:STDOUT:       %.loc10_20: init type = call %Inner.ref.loc10(%T.ref.loc10) [symbolic = @C.%Inner (constants.%Inner.3)]
+// CHECK:STDOUT:       %.loc10_22.1: type = value_of_initializer %.loc10_20 [symbolic = @C.%Inner (constants.%Inner.3)]
+// CHECK:STDOUT:       %.loc10_22.2: type = converted %.loc10_20, %.loc10_22.1 [symbolic = @C.%Inner (constants.%Inner.3)]
+// CHECK:STDOUT:       %return.var.loc10: ref %Inner.3 = var <return slot>
+// CHECK:STDOUT:     }
+// CHECK:STDOUT:     %D.decl: %D.type = fn_decl @D [template = constants.%D] {
+// CHECK:STDOUT:       %Inner.ref.loc13: %Inner.type = name_ref Inner, @Outer.%Inner.decl [template = constants.%Inner.1]
+// CHECK:STDOUT:       %U.ref.loc13: type = name_ref U, @Outer.%U.loc3_15.2 [symbolic = @D.%U (constants.%U)]
+// CHECK:STDOUT:       %.loc13_20: init type = call %Inner.ref.loc13(%U.ref.loc13) [symbolic = @D.%Inner (constants.%Inner.4)]
+// CHECK:STDOUT:       %.loc13_22.1: type = value_of_initializer %.loc13_20 [symbolic = @D.%Inner (constants.%Inner.4)]
+// CHECK:STDOUT:       %.loc13_22.2: type = converted %.loc13_20, %.loc13_22.1 [symbolic = @D.%Inner (constants.%Inner.4)]
+// CHECK:STDOUT:       %return.var.loc13: ref %Inner.4 = var <return slot>
+// CHECK:STDOUT:     }
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !members:
+// CHECK:STDOUT:     .Self = constants.%Inner.2
+// CHECK:STDOUT:     .A = %A.decl
+// CHECK:STDOUT:     .B = %B.decl
+// CHECK:STDOUT:     .C = %C.decl
+// CHECK:STDOUT:     .D = %D.decl
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic fn @A(file.%T.loc2_13.2: type, @Outer.%U.loc3_15.2: type) {
+// CHECK:STDOUT:   %T: type = bind_symbolic_name T 0 [symbolic = %T (constants.%T)]
+// CHECK:STDOUT:   %Outer: type = class_type @Outer, @Outer(%T) [symbolic = %Outer (constants.%Outer.2)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %struct: @A.%Outer (%Outer.2) = struct_value () [symbolic = %struct (constants.%struct.1)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   fn() -> @Inner.%return.var.loc4: %Outer.2 {
+// CHECK:STDOUT:   !entry:
+// CHECK:STDOUT:     %.loc5_15.1: %.2 = struct_literal ()
+// CHECK:STDOUT:     %.loc5_15.2: init @A.%Outer (%Outer.2) = class_init (), @Inner.%return.var.loc4 [symbolic = %struct (constants.%struct.1)]
+// CHECK:STDOUT:     %.loc5_16: init @A.%Outer (%Outer.2) = converted %.loc5_15.1, %.loc5_15.2 [symbolic = %struct (constants.%struct.1)]
+// CHECK:STDOUT:     return %.loc5_16 to @Inner.%return.var.loc4
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic fn @B(file.%T.loc2_13.2: type, @Outer.%U.loc3_15.2: type) {
+// CHECK:STDOUT:   %U: type = bind_symbolic_name U 1 [symbolic = %U (constants.%U)]
+// CHECK:STDOUT:   %Outer: type = class_type @Outer, @Outer(%U) [symbolic = %Outer (constants.%Outer.3)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %struct: @B.%Outer (%Outer.3) = struct_value () [symbolic = %struct (constants.%struct.2)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   fn() -> @Inner.%return.var.loc7: %Outer.3 {
+// CHECK:STDOUT:   !entry:
+// CHECK:STDOUT:     %.loc8_15.1: %.2 = struct_literal ()
+// CHECK:STDOUT:     %.loc8_15.2: init @B.%Outer (%Outer.3) = class_init (), @Inner.%return.var.loc7 [symbolic = %struct (constants.%struct.2)]
+// CHECK:STDOUT:     %.loc8_16: init @B.%Outer (%Outer.3) = converted %.loc8_15.1, %.loc8_15.2 [symbolic = %struct (constants.%struct.2)]
+// CHECK:STDOUT:     return %.loc8_16 to @Inner.%return.var.loc7
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic fn @C(file.%T.loc2_13.2: type, @Outer.%U.loc3_15.2: type) {
+// CHECK:STDOUT:   %T: type = bind_symbolic_name T 0 [symbolic = %T (constants.%T)]
+// CHECK:STDOUT:   %Inner: type = class_type @Inner, @Inner(%T) [symbolic = %Inner (constants.%Inner.3)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %struct: @C.%Inner (%Inner.3) = struct_value () [symbolic = %struct (constants.%struct.3)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   fn() -> @Inner.%return.var.loc10: %Inner.3 {
+// CHECK:STDOUT:   !entry:
+// CHECK:STDOUT:     %.loc11_15.1: %.2 = struct_literal ()
+// CHECK:STDOUT:     %.loc11_15.2: init @C.%Inner (%Inner.3) = class_init (), @Inner.%return.var.loc10 [symbolic = %struct (constants.%struct.3)]
+// CHECK:STDOUT:     %.loc11_16: init @C.%Inner (%Inner.3) = converted %.loc11_15.1, %.loc11_15.2 [symbolic = %struct (constants.%struct.3)]
+// CHECK:STDOUT:     return %.loc11_16 to @Inner.%return.var.loc10
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic fn @D(file.%T.loc2_13.2: type, @Outer.%U.loc3_15.2: type) {
+// CHECK:STDOUT:   %U: type = bind_symbolic_name U 1 [symbolic = %U (constants.%U)]
+// CHECK:STDOUT:   %Inner: type = class_type @Inner, @Inner(%U) [symbolic = %Inner (constants.%Inner.4)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %struct: @D.%Inner (%Inner.4) = struct_value () [symbolic = %struct (constants.%struct.4)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   fn() -> @Inner.%return.var.loc13: %Inner.4 {
+// CHECK:STDOUT:   !entry:
+// CHECK:STDOUT:     %.loc14_15.1: %.2 = struct_literal ()
+// CHECK:STDOUT:     %.loc14_15.2: init @D.%Inner (%Inner.4) = class_init (), @Inner.%return.var.loc13 [symbolic = %struct (constants.%struct.4)]
+// CHECK:STDOUT:     %.loc14_16: init @D.%Inner (%Inner.4) = converted %.loc14_15.1, %.loc14_15.2 [symbolic = %struct (constants.%struct.4)]
+// CHECK:STDOUT:     return %.loc14_16 to @Inner.%return.var.loc13
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @Outer(constants.%T) {
+// CHECK:STDOUT:   %T => constants.%T
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @Inner(constants.%T, constants.%U) {
+// CHECK:STDOUT:   %U => constants.%U
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @Outer(@A.%T) {
+// CHECK:STDOUT:   %T => constants.%T
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @A(constants.%T, constants.%U) {
+// CHECK:STDOUT:   %T => constants.%T
+// CHECK:STDOUT:   %Outer => constants.%Outer.2
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @Outer(constants.%U) {
+// CHECK:STDOUT:   %T => constants.%U
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @Outer(@B.%U) {
+// CHECK:STDOUT:   %T => constants.%U
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @B(constants.%T, constants.%U) {
+// CHECK:STDOUT:   %U => constants.%U
+// CHECK:STDOUT:   %Outer => constants.%Outer.3
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @Inner(constants.%T) {
+// CHECK:STDOUT:   %U => constants.%U
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @Inner(@C.%T) {
+// CHECK:STDOUT:   %U => constants.%U
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @C(constants.%T, constants.%U) {
+// CHECK:STDOUT:   %T => constants.%T
+// CHECK:STDOUT:   %Inner => constants.%Inner.3
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @Inner(constants.%U) {
+// CHECK:STDOUT:   %U => constants.%U
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @Inner(@D.%U) {
+// CHECK:STDOUT:   %U => constants.%U
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @D(constants.%T, constants.%U) {
+// CHECK:STDOUT:   %U => constants.%U
+// CHECK:STDOUT:   %Inner => constants.%Inner.4
+// CHECK:STDOUT: }
+// CHECK:STDOUT: