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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
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toolchain/check/testdata/interop/cpp/function/import/overloads.carbon
Vendored
+18 -18
View File
@@ -777,15 +777,15 @@ import Cpp inline '''
interface I {}
fn EchoValue[ValueT:! I](unused value:! ValueT) {}
fn EchoValue[ValueT: I](unused generic value: ValueT) {}
fn F() {
// CHECK:STDERR: fail_missing_impl.carbon:[[@LINE+7]]:3: error: cannot convert type `<type of Cpp.foo>` into type implementing `I` [ConversionFailureTypeToFacet]
// CHECK:STDERR: EchoValue(Cpp.foo);
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_missing_impl.carbon:[[@LINE-6]]:1: note: while deducing parameters of generic declared here [DeductionGenericHere]
// CHECK:STDERR: fn EchoValue[ValueT:! I](unused value:! ValueT) {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fn EchoValue[ValueT: I](unused generic value: ValueT) {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
EchoValue(Cpp.foo);
}
@@ -4076,20 +4076,20 @@ fn F() {
// CHECK:STDOUT: %I.decl: type = interface_decl @I [concrete = constants.%I.type] {} {}
// CHECK:STDOUT: %EchoValue.decl: %EchoValue.type = fn_decl @EchoValue [concrete = constants.%EchoValue] {
// CHECK:STDOUT: %ValueT.patt.loc10_20.1: %pattern_type.6cb = symbolic_binding_pattern ValueT, 0 [symbolic = %ValueT.patt.loc10_20.2 (constants.%ValueT.patt)]
// CHECK:STDOUT: %value.patt.loc10_38.1: @EchoValue.%pattern_type (%pattern_type.b3a) = symbolic_binding_pattern value, 1 [symbolic = %value.patt.loc10_38.2 (constants.%value.patt)]
// CHECK:STDOUT: %value.patt.loc10_45.1: @EchoValue.%pattern_type (%pattern_type.b3a) = symbolic_binding_pattern value, 1 [symbolic = %value.patt.loc10_45.2 (constants.%value.patt)]
// CHECK:STDOUT: } {
// CHECK:STDOUT: %.loc10_23: type = splice_block %I.ref [concrete = constants.%I.type] {
// CHECK:STDOUT: %.loc10_22: type = splice_block %I.ref [concrete = constants.%I.type] {
// CHECK:STDOUT: %.Self.frozen.loc10_20: %type = symbolic_binding .Self [symbolic_self = constants.%.Self.frozen]
// CHECK:STDOUT: %I.ref: type = name_ref I, file.%I.decl [concrete = constants.%I.type]
// CHECK:STDOUT: }
// CHECK:STDOUT: %ValueT.loc10_20.2: %I.type = symbolic_binding ValueT, 0 [symbolic = %ValueT.loc10_20.1 (constants.%ValueT)]
// CHECK:STDOUT: %.loc10_41.1: type = splice_block %.loc10_41.2 [symbolic = %ValueT.as_type.loc10_41.1 (constants.%ValueT.as_type)] {
// CHECK:STDOUT: %.Self.frozen.loc10_38: %type = symbolic_binding .Self [symbolic_self = constants.%.Self.frozen]
// CHECK:STDOUT: %.loc10_47.1: type = splice_block %.loc10_47.2 [symbolic = %ValueT.as_type.loc10_47.1 (constants.%ValueT.as_type)] {
// CHECK:STDOUT: %.Self.frozen.loc10_45: %type = symbolic_binding .Self [symbolic_self = constants.%.Self.frozen]
// CHECK:STDOUT: %ValueT.ref: %I.type = name_ref ValueT, %ValueT.loc10_20.2 [symbolic = %ValueT.loc10_20.1 (constants.%ValueT)]
// CHECK:STDOUT: %ValueT.as_type.loc10_41.2: type = facet_access_type %ValueT.ref [symbolic = %ValueT.as_type.loc10_41.1 (constants.%ValueT.as_type)]
// CHECK:STDOUT: %.loc10_41.2: type = converted %ValueT.ref, %ValueT.as_type.loc10_41.2 [symbolic = %ValueT.as_type.loc10_41.1 (constants.%ValueT.as_type)]
// CHECK:STDOUT: %ValueT.as_type.loc10_47.2: type = facet_access_type %ValueT.ref [symbolic = %ValueT.as_type.loc10_47.1 (constants.%ValueT.as_type)]
// CHECK:STDOUT: %.loc10_47.2: type = converted %ValueT.ref, %ValueT.as_type.loc10_47.2 [symbolic = %ValueT.as_type.loc10_47.1 (constants.%ValueT.as_type)]
// CHECK:STDOUT: }
// CHECK:STDOUT: %value.loc10_38.2: @EchoValue.%ValueT.as_type.loc10_41.1 (%ValueT.as_type) = symbolic_binding value, 1 [symbolic = %value.loc10_38.1 (constants.%value)]
// CHECK:STDOUT: %value.loc10_45.2: @EchoValue.%ValueT.as_type.loc10_47.1 (%ValueT.as_type) = symbolic_binding value, 1 [symbolic = %value.loc10_45.1 (constants.%value)]
// CHECK:STDOUT: }
// CHECK:STDOUT: %F.decl: %F.type = fn_decl @F [concrete = constants.%F] {} {}
// CHECK:STDOUT: }
@@ -4107,13 +4107,13 @@ fn F() {
// CHECK:STDOUT: !observes:
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: generic fn @EchoValue(%ValueT.loc10_20.2: %I.type, %value.loc10_38.2: @EchoValue.%ValueT.as_type.loc10_41.1 (%ValueT.as_type)) {
// CHECK:STDOUT: generic fn @EchoValue(%ValueT.loc10_20.2: %I.type, %value.loc10_45.2: @EchoValue.%ValueT.as_type.loc10_47.1 (%ValueT.as_type)) {
// CHECK:STDOUT: %ValueT.patt.loc10_20.2: %pattern_type.6cb = symbolic_binding_pattern ValueT, 0 [symbolic = %ValueT.patt.loc10_20.2 (constants.%ValueT.patt)]
// CHECK:STDOUT: %ValueT.loc10_20.1: %I.type = symbolic_binding ValueT, 0 [symbolic = %ValueT.loc10_20.1 (constants.%ValueT)]
// CHECK:STDOUT: %ValueT.as_type.loc10_41.1: type = facet_access_type %ValueT.loc10_20.1 [symbolic = %ValueT.as_type.loc10_41.1 (constants.%ValueT.as_type)]
// CHECK:STDOUT: %pattern_type: type = pattern_type %ValueT.as_type.loc10_41.1 [symbolic = %pattern_type (constants.%pattern_type.b3a)]
// CHECK:STDOUT: %value.patt.loc10_38.2: @EchoValue.%pattern_type (%pattern_type.b3a) = symbolic_binding_pattern value, 1 [symbolic = %value.patt.loc10_38.2 (constants.%value.patt)]
// CHECK:STDOUT: %value.loc10_38.1: @EchoValue.%ValueT.as_type.loc10_41.1 (%ValueT.as_type) = symbolic_binding value, 1 [symbolic = %value.loc10_38.1 (constants.%value)]
// CHECK:STDOUT: %ValueT.as_type.loc10_47.1: type = facet_access_type %ValueT.loc10_20.1 [symbolic = %ValueT.as_type.loc10_47.1 (constants.%ValueT.as_type)]
// CHECK:STDOUT: %pattern_type: type = pattern_type %ValueT.as_type.loc10_47.1 [symbolic = %pattern_type (constants.%pattern_type.b3a)]
// CHECK:STDOUT: %value.patt.loc10_45.2: @EchoValue.%pattern_type (%pattern_type.b3a) = symbolic_binding_pattern value, 1 [symbolic = %value.patt.loc10_45.2 (constants.%value.patt)]
// CHECK:STDOUT: %value.loc10_45.1: @EchoValue.%ValueT.as_type.loc10_47.1 (%ValueT.as_type) = symbolic_binding value, 1 [symbolic = %value.loc10_45.1 (constants.%value)]
// CHECK:STDOUT:
// CHECK:STDOUT: !definition:
// CHECK:STDOUT:
@@ -4142,9 +4142,9 @@ fn F() {
// CHECK:STDOUT: specific @EchoValue(constants.%ValueT, constants.%value) {
// CHECK:STDOUT: %ValueT.patt.loc10_20.2 => constants.%ValueT.patt
// CHECK:STDOUT: %ValueT.loc10_20.1 => constants.%ValueT
// CHECK:STDOUT: %ValueT.as_type.loc10_41.1 => constants.%ValueT.as_type
// CHECK:STDOUT: %ValueT.as_type.loc10_47.1 => constants.%ValueT.as_type
// CHECK:STDOUT: %pattern_type => constants.%pattern_type.b3a
// CHECK:STDOUT: %value.patt.loc10_38.2 => constants.%value.patt
// CHECK:STDOUT: %value.loc10_38.1 => constants.%value
// CHECK:STDOUT: %value.patt.loc10_45.2 => constants.%value.patt
// CHECK:STDOUT: %value.loc10_45.1 => constants.%value
// CHECK:STDOUT: }
// CHECK:STDOUT: