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Detect control flow in entities nested inside functions (#5336)

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Right now, return_scope_stack is being used to determine whether logic
is in a function scope. However, we need to handle nested entities
inside function scopes. For example where this crashes right now:

```
base class C(B:! bool) {}

fn F() {
  class B {
    extend base: C(true or false);
  }
}
```

This is doing a few things to make this kind of code not crash:

- Split `scope_stack().Push` into `PushForDeclName`, `PushForEntity`,
`PushForExpr`, and `PushForFunction` so that better decisions can be
made about behaviors.
- Hide `return_scope_stack` in the API, instead using interfaces to get
at the underlying data.
- Also using `PushForFunction` to update it similar to the other stacks
that `ScopeStack` manages.
- Add `IsInFunctionScope` as the best way to determine presence in
function scope.
- Remove `PeekIsLexicalScope` since destruction really wants function
scope information anyways.
- Clean up `destroy_id_stack` handling to be for function scopes rather
than lexical scopes.
- Return after related `context.TODO`s in a couple more spots, so that
code doesn't proceed to add control flow in spite of the lack of
support.

---------

Co-authored-by: Geoff Romer <gromer@google.com>
This commit is contained in:
Jon Ross-Perkins
2025-04-23 19:03:53 +00:00
committed by GitHub
co-authored by Geoff Romer
parent 51498547c9
commit 03e693873b
22 changed files with 476 additions and 391 deletions
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toolchain/check/testdata/alias/fail_control_flow.carbon
Vendored
+73 -15
View File
@@ -8,35 +8,93 @@
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/alias/fail_control_flow.carbon
// CHECK:STDERR: fail_control_flow.carbon:[[@LINE+16]]:11: error: semantics TODO: `Control flow expressions are currently only supported inside functions.` [SemanticsTodo]
// --- fail_simple.carbon
library "[[@TEST_NAME]]";
// CHECK:STDERR: fail_simple.carbon:[[@LINE+8]]:11: error: semantics TODO: `Control flow expressions are currently only supported inside functions.` [SemanticsTodo]
// CHECK:STDERR: alias a = true or false;
// CHECK:STDERR: ^~~~~~~
// CHECK:STDERR:
// CHECK:STDERR: fail_control_flow.carbon:[[@LINE+12]]:11: error: semantics TODO: `Control flow expressions are currently only supported inside functions.` [SemanticsTodo]
// CHECK:STDERR: alias a = true or false;
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR:
// CHECK:STDERR: fail_control_flow.carbon:[[@LINE+8]]:11: error: semantics TODO: `Control flow expressions are currently only supported inside functions.` [SemanticsTodo]
// CHECK:STDERR: alias a = true or false;
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR:
// CHECK:STDERR: fail_control_flow.carbon:[[@LINE+4]]:11: error: alias initializer must be a name reference [AliasRequiresNameRef]
// CHECK:STDERR: fail_simple.carbon:[[@LINE+4]]:11: error: semantics TODO: `Control flow expressions are currently only supported inside functions.` [SemanticsTodo]
// CHECK:STDERR: alias a = true or false;
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR:
alias a = true or false;
// CHECK:STDOUT: --- fail_control_flow.carbon
// --- fail_nested.carbon
library "[[@TEST_NAME]]";
base class C(B:! bool) {}
fn F() {
class B {
// CHECK:STDERR: fail_nested.carbon:[[@LINE+4]]:20: error: semantics TODO: `Control flow expressions are currently only supported inside functions.` [SemanticsTodo]
// CHECK:STDERR: extend base: C(true or false);
// CHECK:STDERR: ^~~~~~~~~~~~~
// CHECK:STDERR:
extend base: C(true or false);
}
}
// CHECK:STDOUT: --- fail_simple.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: file {}
// CHECK:STDOUT:
// CHECK:STDOUT: --- fail_nested.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %B.7dd: bool = bind_symbolic_name B, 0 [symbolic]
// CHECK:STDOUT: %B.patt: bool = symbolic_binding_pattern B, 0 [symbolic]
// CHECK:STDOUT: %C.type: type = generic_class_type @C [concrete]
// CHECK:STDOUT: %C.generic: %C.type = struct_value () [concrete]
// CHECK:STDOUT: %C: type = class_type @C, @C(%B.7dd) [symbolic]
// CHECK:STDOUT: %empty_struct_type: type = struct_type {} [concrete]
// CHECK:STDOUT: %complete_type: <witness> = complete_type_witness %empty_struct_type [concrete]
// CHECK:STDOUT: %B.d97: type = class_type @B [concrete]
// CHECK:STDOUT: %true: bool = bool_literal true [concrete]
// CHECK:STDOUT: %false: bool = bool_literal false [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: imports {
// CHECK:STDOUT: file {}
// CHECK:STDOUT:
// CHECK:STDOUT: generic class @C(<unexpected>.inst27.loc4_14: bool) {
// CHECK:STDOUT: %B: bool = bind_symbolic_name B, 0 [symbolic = %B (constants.%B.7dd)]
// CHECK:STDOUT: %B.patt.loc4_14.2: bool = symbolic_binding_pattern B, 0 [symbolic = %B.patt.loc4_14.2 (constants.%B.patt)]
// CHECK:STDOUT:
// CHECK:STDOUT: !definition:
// CHECK:STDOUT:
// CHECK:STDOUT: class {
// CHECK:STDOUT: %empty_struct_type: type = struct_type {} [concrete = constants.%empty_struct_type]
// CHECK:STDOUT: %complete_type: <witness> = complete_type_witness %empty_struct_type [concrete = constants.%complete_type]
// CHECK:STDOUT: complete_type_witness = %complete_type
// CHECK:STDOUT:
// CHECK:STDOUT: !members:
// CHECK:STDOUT: .Self = constants.%C
// CHECK:STDOUT: }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: file {
// CHECK:STDOUT: %.loc27: bool = block_arg <unexpected instblockref inst_block5> [concrete = constants.%true]
// CHECK:STDOUT: %a: <error> = bind_alias a, <error> [concrete = <error>]
// CHECK:STDOUT: class @B {
// CHECK:STDOUT: %C.ref: %C.type = name_ref C, <unexpected>.inst32.loc4_24 [concrete = constants.%C.generic]
// CHECK:STDOUT: %true.loc12_20: bool = bool_literal true [concrete = constants.%true]
// CHECK:STDOUT: %.loc12: bool = not %true.loc12_20 [concrete = constants.%false]
// CHECK:STDOUT: %true.loc12_25: bool = bool_literal true [concrete = constants.%true]
// CHECK:STDOUT: if %.loc12 br !or.rhs else br !or.result(%true.loc12_25)
// CHECK:STDOUT: complete_type_witness = invalid
// CHECK:STDOUT:
// CHECK:STDOUT: !members:
// CHECK:STDOUT: .Self = constants.%B.d97
// CHECK:STDOUT: .C = <poisoned>
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: fn @F();
// CHECK:STDOUT:
// CHECK:STDOUT: specific @C(constants.%B.7dd) {
// CHECK:STDOUT: %B => constants.%B.7dd
// CHECK:STDOUT: %B.patt.loc4_14.2 => constants.%B.patt
// CHECK:STDOUT: }
// CHECK:STDOUT: