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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/parse/testdata/generics/generic_params/basic.carbon
Vendored
+3 -3
View File
@@ -8,7 +8,7 @@
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/parse/testdata/generics/generic_params/basic.carbon
fn foo(a:! i32);
fn foo(generic a: i32);
// CHECK:STDOUT: - filename: basic.carbon
// CHECK:STDOUT: parse_tree: [
@@ -17,9 +17,9 @@ fn foo(a:! i32);
// CHECK:STDOUT: {kind: 'IdentifierNameMaybeBeforeSignature', text: 'foo'},
// CHECK:STDOUT: {kind: 'ExplicitParamListStart', text: '('},
// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'a'},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPatternStart', text: ':!', subtree_size: 2},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPatternStart', text: ':', subtree_size: 2},
// CHECK:STDOUT: {kind: 'IntTypeLiteral', text: 'i32'},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPattern', text: ':!', subtree_size: 4},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPattern', text: ':', subtree_size: 4},
// CHECK:STDOUT: {kind: 'ExplicitParamList', text: ')', subtree_size: 6},
// CHECK:STDOUT: {kind: 'FunctionDecl', text: ';', subtree_size: 9},
// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
toolchain/parse/testdata/generics/generic_params/fail_template_no_param.carbon
Vendored
+26 -42
View File
@@ -8,37 +8,31 @@
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/parse/testdata/generics/generic_params/fail_template_no_param.carbon
// CHECK:STDERR: fail_template_no_param.carbon:[[@LINE+4]]:15: error: expected name in binding pattern [ExpectedBindingPattern]
// --- fail_template_before_type.carbon
// CHECK:STDERR: fail_template_before_type.carbon:[[@LINE+4]]:15: error: expected name in binding pattern [ExpectedBindingPattern]
// CHECK:STDERR: fn A(template i32);
// CHECK:STDERR: ^~~
// CHECK:STDERR:
fn A(template i32);
// CHECK:STDERR: fail_template_no_param.carbon:[[@LINE+4]]:6: error: expected `:!` binding after `template` [ExpectedGenericBindingPatternAfterTemplate]
// CHECK:STDERR: fn B(template a: i32);
// CHECK:STDERR: ^~~~~~~~
// CHECK:STDERR:
fn B(template a: i32);
// --- fail_template_no_name.carbon
// CHECK:STDERR: fail_template_no_param.carbon:[[@LINE+4]]:14: error: expected name in binding pattern [ExpectedBindingPattern]
// CHECK:STDERR: fail_template_no_name.carbon:[[@LINE+4]]:14: error: expected name in binding pattern [ExpectedBindingPattern]
// CHECK:STDERR: fn C(template);
// CHECK:STDERR: ^
// CHECK:STDERR:
fn C(template);
// CHECK:STDERR: fail_template_no_param.carbon:[[@LINE+4]]:14: error: expected name in binding pattern [ExpectedBindingPattern]
// CHECK:STDERR: fn D(template:! i32);
// CHECK:STDERR: ^~
// CHECK:STDERR:
fn D(template:! i32);
// --- fail_reserved_word_after_generic.carbon
// CHECK:STDERR: fail_template_no_param.carbon:[[@LINE+4]]:14: error: expected name in binding pattern [ExpectedBindingPattern]
// CHECK:STDERR: fn E(template:! i32);
// CHECK:STDERR: ^~
// CHECK:STDERR: fail_reserved_word_after_generic.carbon:[[@LINE+4]]:22: error: expected name in binding pattern; prefix reserved word with `r#` to form a valid identifier [ExpectedBindingPattern]
// CHECK:STDERR: fn E(generic template: i32);
// CHECK:STDERR: ^
// CHECK:STDERR:
fn E(template:! i32);
fn E(generic template: i32);
// CHECK:STDOUT: - filename: fail_template_no_param.carbon
// CHECK:STDOUT: - filename: fail_template_before_type.carbon
// CHECK:STDOUT: parse_tree: [
// CHECK:STDOUT: {kind: 'FileStart', text: ''},
// CHECK:STDOUT: {kind: 'FunctionIntroducer', text: 'fn'},
@@ -49,15 +43,11 @@ fn E(template:! i32);
// CHECK:STDOUT: {kind: 'LetBindingPattern', text: 'template', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'ExplicitParamList', text: ')', has_error: yes, subtree_size: 5},
// CHECK:STDOUT: {kind: 'FunctionDecl', text: ';', subtree_size: 8},
// CHECK:STDOUT: {kind: 'FunctionIntroducer', text: 'fn'},
// CHECK:STDOUT: {kind: 'IdentifierNameMaybeBeforeSignature', text: 'B'},
// CHECK:STDOUT: {kind: 'ExplicitParamListStart', text: '('},
// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'a'},
// CHECK:STDOUT: {kind: 'TemplateBindingName', text: 'template', has_error: yes, subtree_size: 2},
// CHECK:STDOUT: {kind: 'IntTypeLiteral', text: 'i32'},
// CHECK:STDOUT: {kind: 'LetBindingPattern', text: ':', has_error: yes, subtree_size: 4},
// CHECK:STDOUT: {kind: 'ExplicitParamList', text: ')', has_error: yes, subtree_size: 6},
// CHECK:STDOUT: {kind: 'FunctionDecl', text: ';', subtree_size: 9},
// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
// CHECK:STDOUT: ]
// CHECK:STDOUT: - filename: fail_template_no_name.carbon
// CHECK:STDOUT: parse_tree: [
// CHECK:STDOUT: {kind: 'FileStart', text: ''},
// CHECK:STDOUT: {kind: 'FunctionIntroducer', text: 'fn'},
// CHECK:STDOUT: {kind: 'IdentifierNameMaybeBeforeSignature', text: 'C'},
// CHECK:STDOUT: {kind: 'ExplicitParamListStart', text: '('},
@@ -66,25 +56,19 @@ fn E(template:! i32);
// CHECK:STDOUT: {kind: 'LetBindingPattern', text: 'template', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'ExplicitParamList', text: ')', has_error: yes, subtree_size: 5},
// CHECK:STDOUT: {kind: 'FunctionDecl', text: ';', subtree_size: 8},
// CHECK:STDOUT: {kind: 'FunctionIntroducer', text: 'fn'},
// CHECK:STDOUT: {kind: 'IdentifierNameMaybeBeforeSignature', text: 'D'},
// CHECK:STDOUT: {kind: 'ExplicitParamListStart', text: '('},
// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: ':!', has_error: yes},
// CHECK:STDOUT: {kind: 'TemplateBindingName', text: 'template', has_error: yes, subtree_size: 2},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPatternStart', text: ':!', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'IntTypeLiteral', text: 'i32'},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPattern', text: ':!', has_error: yes, subtree_size: 5},
// CHECK:STDOUT: {kind: 'ExplicitParamList', text: ')', has_error: yes, subtree_size: 7},
// CHECK:STDOUT: {kind: 'FunctionDecl', text: ';', subtree_size: 10},
// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
// CHECK:STDOUT: ]
// CHECK:STDOUT: - filename: fail_reserved_word_after_generic.carbon
// CHECK:STDOUT: parse_tree: [
// CHECK:STDOUT: {kind: 'FileStart', text: ''},
// CHECK:STDOUT: {kind: 'FunctionIntroducer', text: 'fn'},
// CHECK:STDOUT: {kind: 'IdentifierNameMaybeBeforeSignature', text: 'E'},
// CHECK:STDOUT: {kind: 'ExplicitParamListStart', text: '('},
// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: ':!', has_error: yes},
// CHECK:STDOUT: {kind: 'TemplateBindingName', text: 'template', has_error: yes, subtree_size: 2},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPatternStart', text: ':!', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'template'},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPatternStart', text: ':', subtree_size: 2},
// CHECK:STDOUT: {kind: 'IntTypeLiteral', text: 'i32'},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPattern', text: ':!', has_error: yes, subtree_size: 5},
// CHECK:STDOUT: {kind: 'ExplicitParamList', text: ')', has_error: yes, subtree_size: 7},
// CHECK:STDOUT: {kind: 'FunctionDecl', text: ';', subtree_size: 10},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPattern', text: ':', subtree_size: 4},
// CHECK:STDOUT: {kind: 'ExplicitParamList', text: ')', subtree_size: 6},
// CHECK:STDOUT: {kind: 'FunctionDecl', text: ';', subtree_size: 9},
// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
// CHECK:STDOUT: ]
toolchain/parse/testdata/generics/generic_params/template.carbon
Vendored
+19 -20
View File
@@ -10,27 +10,27 @@
// --- basic.carbon
fn foo(template a:! i32);
fn foo(template a: i32);
// --- fail_template_ref.carbon
// CHECK:STDERR: fail_template_ref.carbon:[[@LINE+4]]:17: error: expected `:` binding after `ref` [ExpectedRuntimeBindingPatternAfterRef]
// CHECK:STDERR: fn foo(template ref a:! i32);
// CHECK:STDERR: fail_template_ref.carbon:[[@LINE+4]]:17: error: `ref` is only allowed on a runtime binding [ExpectedRuntimeBindingPatternAfterRef]
// CHECK:STDERR: fn foo(template ref a: i32);
// CHECK:STDERR: ^~~
// CHECK:STDERR:
fn foo(template ref a:! i32);
fn foo(template ref a: i32);
// CHECK:STDERR: fail_template_ref.carbon:[[@LINE+4]]:8: error: expected `:!` binding after `template` [ExpectedGenericBindingPatternAfterTemplate]
// CHECK:STDERR: fail_template_ref.carbon:[[@LINE+4]]:17: error: `ref` is only allowed on a runtime binding [ExpectedRuntimeBindingPatternAfterRef]
// CHECK:STDERR: fn foo(template ref a: i32);
// CHECK:STDERR: ^~~~~~~~
// CHECK:STDERR: ^~~
// CHECK:STDERR:
fn foo(template ref a: i32);
// CHECK:STDERR: fail_template_ref.carbon:[[@LINE+4]]:12: error: expected name in binding pattern [ExpectedBindingPattern]
// CHECK:STDERR: fn foo(ref template a:! i32);
// CHECK:STDERR: fn foo(ref template a: i32);
// CHECK:STDERR: ^~~~~~~~
// CHECK:STDERR:
fn foo(ref template a:! i32);
fn foo(ref template a: i32);
// CHECK:STDOUT: - filename: basic.carbon
// CHECK:STDOUT: parse_tree: [
@@ -40,9 +40,9 @@ fn foo(ref template a:! i32);
// CHECK:STDOUT: {kind: 'ExplicitParamListStart', text: '('},
// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'a'},
// CHECK:STDOUT: {kind: 'TemplateBindingName', text: 'template', subtree_size: 2},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPatternStart', text: ':!', subtree_size: 3},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPatternStart', text: ':', subtree_size: 3},
// CHECK:STDOUT: {kind: 'IntTypeLiteral', text: 'i32'},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPattern', text: ':!', subtree_size: 5},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPattern', text: ':', subtree_size: 5},
// CHECK:STDOUT: {kind: 'ExplicitParamList', text: ')', subtree_size: 7},
// CHECK:STDOUT: {kind: 'FunctionDecl', text: ';', subtree_size: 10},
// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
@@ -53,22 +53,21 @@ fn foo(ref template a:! i32);
// CHECK:STDOUT: {kind: 'FunctionIntroducer', text: 'fn'},
// CHECK:STDOUT: {kind: 'IdentifierNameMaybeBeforeSignature', text: 'foo'},
// CHECK:STDOUT: {kind: 'ExplicitParamListStart', text: '('},
// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'a'},
// CHECK:STDOUT: {kind: 'TemplateBindingName', text: 'template', subtree_size: 2},
// CHECK:STDOUT: {kind: 'RefBindingName', text: 'ref', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPatternStart', text: ':!', has_error: yes, subtree_size: 4},
// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'a'},
// CHECK:STDOUT: {kind: 'TemplateBindingName', text: 'template', subtree_size: 2},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPatternStart', text: ':', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'IntTypeLiteral', text: 'i32'},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPattern', text: ':!', has_error: yes, subtree_size: 6},
// CHECK:STDOUT: {kind: 'ExplicitParamList', text: ')', has_error: yes, subtree_size: 8},
// CHECK:STDOUT: {kind: 'FunctionDecl', text: ';', subtree_size: 11},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPattern', text: ':', has_error: yes, subtree_size: 5},
// CHECK:STDOUT: {kind: 'ExplicitParamList', text: ')', has_error: yes, subtree_size: 7},
// CHECK:STDOUT: {kind: 'FunctionDecl', text: ';', subtree_size: 10},
// CHECK:STDOUT: {kind: 'FunctionIntroducer', text: 'fn'},
// CHECK:STDOUT: {kind: 'IdentifierNameMaybeBeforeSignature', text: 'foo'},
// CHECK:STDOUT: {kind: 'ExplicitParamListStart', text: '('},
// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'a'},
// CHECK:STDOUT: {kind: 'TemplateBindingName', text: 'template', has_error: yes, subtree_size: 2},
// CHECK:STDOUT: {kind: 'RefBindingName', text: 'ref', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'TemplateBindingName', text: 'template', subtree_size: 2},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPatternStart', text: ':', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'IntTypeLiteral', text: 'i32'},
// CHECK:STDOUT: {kind: 'LetBindingPattern', text: ':', has_error: yes, subtree_size: 5},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPattern', text: ':', has_error: yes, subtree_size: 5},
// CHECK:STDOUT: {kind: 'ExplicitParamList', text: ')', has_error: yes, subtree_size: 7},
// CHECK:STDOUT: {kind: 'FunctionDecl', text: ';', subtree_size: 10},
// CHECK:STDOUT: {kind: 'FunctionIntroducer', text: 'fn'},