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Replace :! binding syntax with phase keywords and contextual defaults (#7479)

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Implement the toolchain side of proposal #7254, removing the `:!`
binding
syntax for generic and template parameters in favor of the keywords
`generic`,
`template`, and `runtime` plus contextual defaults for phase.

For valid programs this is semantics-preserving: each binding resolves
to the
same phase, and produces the same SemIR, as it did under `:!`/`:`. The
parser
derives a binding's phase from its syntactic context plus any explicit
phase
keyword; new diagnostics and error recovery for misused keywords are
described
below.

Implementation details for each component:

- Lexer: remove the `:!` (`ColonExclaim`) token, move its virtual
parse-node
  budget onto `:`, and add the `generic` and `runtime` keywords.
- Parser: thread a `BindingContext` (`ExplicitParam`, `DeducedParam`, or
`CompileTimeEntityParam`) from declaration introducers down through
parameter
lists to each binding pattern, using a one-token lookahead to
distinguish a
name-qualifier parameter list from a declaration's own final list.
Parameters
of a compile-time entity (`class`, `interface`, `constraint`, `choice`,
`alias`, `export`, `namespace`) and deduced `[]` parameters default to
checked
generic; explicit function parameters and local bindings default to
runtime.
`HandleBindingPattern` resolves the phase from that context plus the
keyword: a
`generic` keyword needs no node of its own (the phase is carried by the
  binding's node kind), while a `runtime` keyword is preserved as a
`RuntimeBindingName` node so `check` can name it in a diagnostic. A
phase
keyword that is merely redundant with the contextual default is
diagnosed
  here, without invalidating the parse tree.
- Check: a phase keyword that is invalid for its context (for example
`runtime`
on a checked-generic parameter) is diagnosed here, and recovers by
building an
error binding that still introduces the name so that later uses of it do
not
  produce cascading errors.

The removed `:!` syntax is now rejected as an ordinary parse error.

The `form`/`:?`/`->?` ("extended types") portion of proposal #7254 is
left for a
separate change.

Assisted-by: Claude Code
This commit is contained in:
Chandler Carruth
2026-07-11 01:22:44 +00:00
committed by GitHub
parent bf106c3b4b
commit 8be274cf60
482 changed files with 16917 additions and 16226 deletions
Download Patch File Download Diff File Expand all files Collapse all files
toolchain/check/testdata/where_expr/dot_self_impls.carbon
Vendored
+35 -35
View File
@@ -23,7 +23,7 @@ interface J {
fn GSelf(self);
}
fn INotJ[T:! I where .Self impls J](x: T) {
fn INotJ[T: I where .Self impls J](x: T) {
// Can access members of `I` using either kind of member access.
T.FNonInstance();
T.(I.FNonInstance)();
@@ -39,7 +39,7 @@ fn INotJ[T:! I where .Self impls J](x: T) {
x.(J.GSelf)();
}
fn TypeNotJ[T:! type where .Self impls J](x: T) {
fn TypeNotJ[T: type where .Self impls J](x: T) {
T.(J.GNonInstance)();
x.(J.GSelf)();
}
@@ -55,7 +55,7 @@ interface J {
fn F() -> {};
}
fn INotJ(T:! I where .Self impls J) {
fn INotJ(generic T: I where .Self impls J) {
// Gets `T.(I.F)`. Doesn't consider `T.(J.F)`, so no ambiguity.
let unused x: () = T.F();
}
@@ -71,7 +71,7 @@ interface J {
fn G();
}
fn INotJ(T:! I where .Self impls J) {
fn INotJ(generic T: I where .Self impls J) {
// CHECK:STDERR: fail_name_lookup_through_where_self_impls.carbon:[[@LINE+4]]:3: error: member name `G` not found in `I` [MemberNameNotFoundInSpecificScope]
// CHECK:STDERR: T.G();
// CHECK:STDERR: ^~~
@@ -86,7 +86,7 @@ interface J {
fn G();
}
fn TypeNotJ(T:! type where .Self impls J) {
fn TypeNotJ(generic T: type where .Self impls J) {
// CHECK:STDERR: fail_name_lookup_with_type.carbon:[[@LINE+4]]:3: error: member name `G` not found [MemberNameNotFound]
// CHECK:STDERR: T.G();
// CHECK:STDERR: ^~~
@@ -100,7 +100,7 @@ library "[[@TEST_NAME]]";
interface A {}
interface B { fn Bfn(); }
fn F(T:! A & B) {
fn F(generic T: A & B) {
// CHECK:STDERR: fail_facet_type_simple_member_access.carbon:[[@LINE+4]]:6: error: member name `Bfn` not found in `A` [MemberNameNotFoundInSpecificScope]
// CHECK:STDERR: T.((A where .Self impls B).Bfn)();
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -127,7 +127,7 @@ interface J {
fn GSelf(self);
}
fn INotJ[T:! I where .Self impls J](x: T) {
fn INotJ[T: I where .Self impls J](x: T) {
// CHECK:STDERR: fail_name_lookup_instance.carbon:[[@LINE+4]]:3: error: member name `GNonInstance` not found in `I` [MemberNameNotFoundInSpecificScope]
// CHECK:STDERR: x.GNonInstance();
// CHECK:STDERR: ^~~~~~~~~~~~~~
@@ -144,9 +144,9 @@ fn INotJ[T:! I where .Self impls J](x: T) {
// --- compare_equal.carbon
library "[[@TEST_NAME]]";
class WrapType(T:! type) {}
fn AssertSame[T:! type](unused a: WrapType(T), unused b: WrapType(T)) {}
fn Type(T:! type) -> WrapType(T) { return {}; }
class WrapType(T: type) {}
fn AssertSame[T: type](unused a: WrapType(T), unused b: WrapType(T)) {}
fn Type(generic T: type) -> WrapType(T) { return {}; }
interface I;
interface J;
@@ -171,12 +171,12 @@ interface K {}
// --- fail_todo_compare_equal_with_rewrite.carbon
library "[[@TEST_NAME]]";
class WrapType(T:! type) {}
fn AssertSame[T:! type](unused a: WrapType(T), unused b: WrapType(T)) {}
fn Type(T:! type) -> WrapType(T) { return {}; }
class WrapType(T: type) {}
fn AssertSame[T: type](unused a: WrapType(T), unused b: WrapType(T)) {}
fn Type(generic T: type) -> WrapType(T) { return {}; }
interface I { let A:! type; }
interface J { let B:! type; }
interface I { let A: type; }
interface J { let B: type; }
// TODO: The `.Self` implied in `.A` contains all of the extended interfaces,
// which is different between these facet types at the point where `.A` is
@@ -192,8 +192,8 @@ fn Test() {
// CHECK:STDERR: AssertSame(Type((I where .A = ()) & J),
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_todo_compare_equal_with_rewrite.carbon:[[@LINE-19]]:1: note: while deducing parameters of generic declared here [DeductionGenericHere]
// CHECK:STDERR: fn AssertSame[T:! type](unused a: WrapType(T), unused b: WrapType(T)) {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fn AssertSame[T: type](unused a: WrapType(T), unused b: WrapType(T)) {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
AssertSame(Type((I where .A = ()) & J),
Type(I & J where .A = ()));
@@ -202,8 +202,8 @@ fn Test() {
// CHECK:STDERR: AssertSame(Type(I & (J where .B = {})),
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_todo_compare_equal_with_rewrite.carbon:[[@LINE-29]]:1: note: while deducing parameters of generic declared here [DeductionGenericHere]
// CHECK:STDERR: fn AssertSame[T:! type](unused a: WrapType(T), unused b: WrapType(T)) {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fn AssertSame[T: type](unused a: WrapType(T), unused b: WrapType(T)) {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
AssertSame(Type(I & (J where .B = {})),
Type(I & J where .B = {}));
@@ -213,8 +213,8 @@ fn Test() {
// CHECK:STDERR: AssertSame(Type((I where .A = ()) & (J where .B = {})),
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_todo_compare_equal_with_rewrite.carbon:[[@LINE-40]]:1: note: while deducing parameters of generic declared here [DeductionGenericHere]
// CHECK:STDERR: fn AssertSame[T:! type](unused a: WrapType(T), unused b: WrapType(T)) {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fn AssertSame[T: type](unused a: WrapType(T), unused b: WrapType(T)) {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
AssertSame(Type((I where .A = ()) & (J where .B = {})),
Type(I & J where .A = () and .B = {}));
@@ -223,9 +223,9 @@ fn Test() {
// --- fail_compare_not_equal.carbon
library "[[@TEST_NAME]]";
class WrapType(T:! type) {}
fn Same[T:! type](unused a: WrapType(T), unused b: WrapType(T)) {}
fn Type(T:! type) -> WrapType(T) { return {}; }
class WrapType(T: type) {}
fn Same[T: type](unused a: WrapType(T), unused b: WrapType(T)) {}
fn Type(generic T: type) -> WrapType(T) { return {}; }
interface I {}
interface J {}
@@ -235,8 +235,8 @@ fn Test() {
// CHECK:STDERR: Same(Type(I where .Self impls J), Type(J where .Self impls I));
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_compare_not_equal.carbon:[[@LINE-10]]:1: note: while deducing parameters of generic declared here [DeductionGenericHere]
// CHECK:STDERR: fn Same[T:! type](unused a: WrapType(T), unused b: WrapType(T)) {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fn Same[T: type](unused a: WrapType(T), unused b: WrapType(T)) {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
Same(Type(I where .Self impls J), Type(J where .Self impls I));
}
@@ -244,12 +244,12 @@ fn Test() {
// --- todo_fail_compare_not_equal_with_same_type.carbon
library "[[@TEST_NAME]]";
class WrapType(T:! type) {}
fn Same[T:! type](unused a: WrapType(T), unused b: WrapType(T)) {}
fn Type(T:! type) -> WrapType(T) { return {}; }
class WrapType(T: type) {}
fn Same[T: type](unused a: WrapType(T), unused b: WrapType(T)) {}
fn Type(generic T: type) -> WrapType(T) { return {}; }
interface I { let A:! type; }
interface J { let B:! type; }
interface I { let A: type; }
interface J { let B: type; }
fn Test() {
// The first `.A` has a `.Self` of type `I`. The second contains a `.Self` of
@@ -266,7 +266,7 @@ library "[[@TEST_NAME]]";
class C {}
interface I {}
interface J { let T:! type; }
interface J { let T: type; }
// Interfaces to the right of the `where` don't interfere with the
// "can only impl a facet type with a single interface" rule. Only
@@ -278,8 +278,8 @@ impl {.b: C} as J where .Self impls I and .T = () {}
// --- impl_with_rewrite_of_interface_not_being_implemented.carbon
library "[[@TEST_NAME]]";
interface I { let A:! type; }
interface J { let A:! type; }
interface I { let A: type; }
interface J { let A: type; }
class C {}
@@ -287,7 +287,7 @@ class C {}
impl C as J where .A = {} {}
// Requirement of implementing J with `.A = A`.
constraint NeedJ(A:! type) {
constraint NeedJ(A: type) {
require impls J where .A = A;
}