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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/class/method/generic_method.carbon
Vendored
+11 -11
View File
@@ -12,12 +12,12 @@
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/class/method/generic_method.carbon
class Class(T:! type) {
class Class(T: type) {
var a: T;
fn F(self, n: T);
}
fn Class(T:! type).F(unused self, unused n: T) {}
fn Class(T: type).F(unused self, unused n: T) {}
// CHECK:STDOUT: --- generic_method.carbon
@@ -63,9 +63,9 @@ fn Class(T:! type).F(unused self, unused n: T) {}
// CHECK:STDOUT: %Class.decl: %Class.type = class_decl @Class [concrete = constants.%Class.generic] {
// CHECK:STDOUT: %T.patt.loc15_14.1: %pattern_type.98f = symbolic_binding_pattern T, 0 [symbolic = %T.patt.loc15_14.2 (constants.%T.patt)]
// CHECK:STDOUT: } {
// CHECK:STDOUT: %.loc15_17.1: type = splice_block %.loc15_17.2 [concrete = type] {
// CHECK:STDOUT: %.loc15_16.1: type = splice_block %.loc15_16.2 [concrete = type] {
// CHECK:STDOUT: %.Self.frozen: %type = symbolic_binding .Self [symbolic_self = constants.%.Self.frozen]
// CHECK:STDOUT: %.loc15_17.2: type = type_literal type [concrete = type]
// CHECK:STDOUT: %.loc15_16.2: type = type_literal type [concrete = type]
// CHECK:STDOUT: }
// CHECK:STDOUT: %T.loc15_14.2: type = symbolic_binding T, 0 [symbolic = %T.loc15_14.1 (constants.%T)]
// CHECK:STDOUT: }
@@ -75,15 +75,15 @@ fn Class(T:! type).F(unused self, unused n: T) {}
// CHECK:STDOUT: %n.param_patt.loc20: @Class.F.%pattern_type.loc17_15 (%pattern_type.51d) = value_param_pattern [symbolic = %n.param_patt.loc17 (constants.%n.param_patt)]
// CHECK:STDOUT: %n.patt.loc20: @Class.F.%pattern_type.loc17_15 (%pattern_type.51d) = at_binding_pattern n, %n.param_patt.loc20 [symbolic = %n.patt.loc17 (constants.%n.patt)]
// CHECK:STDOUT: } {
// CHECK:STDOUT: %.loc20_14.1: type = splice_block %.loc20_14.2 [concrete = type] {
// CHECK:STDOUT: %.loc20_13.1: type = splice_block %.loc20_13.2 [concrete = type] {
// CHECK:STDOUT: %.Self.frozen: %type = symbolic_binding .Self [symbolic_self = constants.%.Self.frozen]
// CHECK:STDOUT: %.loc20_14.2: type = type_literal type [concrete = type]
// CHECK:STDOUT: %.loc20_13.2: type = type_literal type [concrete = type]
// CHECK:STDOUT: }
// CHECK:STDOUT: %T.loc20: type = symbolic_binding T, 0 [symbolic = @Class.%T.loc15_14.1 (constants.%T)]
// CHECK:STDOUT: %self.param.loc20: @Class.F.%Class (%Class) = value_param call_param0
// CHECK:STDOUT: %.loc20_29.1: type = splice_block %Self.ref.loc20 [symbolic = %Class (constants.%Class)] {
// CHECK:STDOUT: %.loc20_29.2: type = specific_constant constants.%Class, @Class(constants.%T) [symbolic = %Class (constants.%Class)]
// CHECK:STDOUT: %Self.ref.loc20: type = name_ref Self, %.loc20_29.2 [symbolic = %Class (constants.%Class)]
// CHECK:STDOUT: %.loc20_28.1: type = splice_block %Self.ref.loc20 [symbolic = %Class (constants.%Class)] {
// CHECK:STDOUT: %.loc20_28.2: type = specific_constant constants.%Class, @Class(constants.%T) [symbolic = %Class (constants.%Class)]
// CHECK:STDOUT: %Self.ref.loc20: type = name_ref Self, %.loc20_28.2 [symbolic = %Class (constants.%Class)]
// CHECK:STDOUT: }
// CHECK:STDOUT: %self.loc20: @Class.F.%Class (%Class) = wrapper_binding self, %self.param.loc20
// CHECK:STDOUT: %n.param.loc20: @Class.F.%T.loc17 (%T) = value_param call_param1
@@ -147,8 +147,8 @@ fn Class(T:! type).F(unused self, unused n: T) {}
// CHECK:STDOUT: %n.patt.loc17: @Class.F.%pattern_type.loc17_15 (%pattern_type.51d) = at_binding_pattern n, %n.param_patt.loc17 [symbolic = %n.patt.loc17 (constants.%n.patt)]
// CHECK:STDOUT:
// CHECK:STDOUT: !definition:
// CHECK:STDOUT: %require_complete.loc20_29: <witness> = require_complete_type %Class [symbolic = %require_complete.loc20_29 (constants.%require_complete.4d9)]
// CHECK:STDOUT: %require_complete.loc20_43: <witness> = require_complete_type %T.loc17 [symbolic = %require_complete.loc20_43 (constants.%require_complete.944)]
// CHECK:STDOUT: %require_complete.loc20_28: <witness> = require_complete_type %Class [symbolic = %require_complete.loc20_28 (constants.%require_complete.4d9)]
// CHECK:STDOUT: %require_complete.loc20_42: <witness> = require_complete_type %T.loc17 [symbolic = %require_complete.loc20_42 (constants.%require_complete.944)]
// CHECK:STDOUT:
// CHECK:STDOUT: fn(%self.param.loc20: @Class.F.%Class (%Class), %n.param.loc20: @Class.F.%T.loc17 (%T)) {
// CHECK:STDOUT: !entry: