Files
carbon-lang/toolchain/parse/testdata/function/declaration.carbon
T
David BlaikieandNicholas Bishop 059ee7b9ed Parse -> ref T as a primitive return form (#7911)
Previously `-> ref T` was parsed as a type expression whose outermost
node is a `ref` prefix operator (the same one used for `F(ref x)`
arguments), and `ReturnExprAsForm` recognized the resulting `RefTagExpr`
and turned it into a `RefForm`.

Per p5434, a return form that begins with `val`, `ref`, or `var` is not
a type expression. Parse a leading `ref` after `->` as a
`RefPrimitiveForm` node wrapping the type expression, reusing the node
produced by `form(ref T)`, and check it as a form. This prepares for
supporting `-> val T` and `-> var T` in the same way.

The only SemIR change is that the `ref_tag` instruction is no longer
emitted, and the return slot pattern refers to a `type_component_of` the
form, matching `->? form(ref T)`.

---------

Co-authored-by: Nicholas Bishop <nbishop@nbishop.net>
2026-10-07 23:05:55 +00:00

573 lines
25 KiB
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// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
// AUTOUPDATE
// TIP: To test this file alone, run:
// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/parse/testdata/function/declaration.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/parse/testdata/function/declaration.carbon
// --- basic.carbon
fn F();
// --- ref.carbon
fn foo(ref a: i32);
// --- implicit_empty.carbon
fn foo[]();
// --- implicit_params.carbon
fn foo[a: i32, b: i32]();
// --- no_params.carbon
fn foo {}
// --- params.carbon
fn foo(a: i32, b: i32);
// --- with_return_type.carbon
fn foo() -> u32;
// --- impl_fn.carbon
override fn F();
abstract override fn G();
override abstract fn H();
private override default fn I();
// --- fail_identifier_instead_of_sig.carbon
// CHECK:STDERR: fail_identifier_instead_of_sig.carbon:[[@LINE+4]]:8: error: `fn` declarations must either end with a `;` or have a `{ ... }` block for a definition [ExpectedDeclSemiOrDefinition]
// CHECK:STDERR: fn foo bar;
// CHECK:STDERR: ^~~
// CHECK:STDERR:
fn foo bar;
// --- fail_missing_implicit_close.carbon
// CHECK:STDERR: fail_missing_implicit_close.carbon:[[@LINE+7]]:7: error: opening symbol without a corresponding closing symbol [UnmatchedOpening]
// CHECK:STDERR: fn Div[();
// CHECK:STDERR: ^
// CHECK:STDERR: fail_missing_implicit_close.carbon:[[@LINE+4]]:10: note: possibly missing `]` here [PossiblyMissingBracketHere]
// CHECK:STDERR: fn Div[();
// CHECK:STDERR: ^
// CHECK:STDERR:
fn Div[();
// --- fail_missing_name.carbon
// CHECK:STDERR: fail_missing_name.carbon:[[@LINE+4]]:4: error: `fn` introducer should be followed by a name [ExpectedDeclName]
// CHECK:STDERR: fn ();
// CHECK:STDERR: ^
// CHECK:STDERR:
fn ();
// --- fail_no_sig_or_semi.carbon
fn foo
// CHECK:STDERR: fail_no_sig_or_semi.carbon:[[@LINE+4]]:1: error: `fn` declarations must either end with a `;` or have a `{ ... }` block for a definition [ExpectedDeclSemiOrDefinition]
// CHECK:STDERR:
// CHECK:STDERR: ^
// CHECK:STDERR:
// --- fail_only_fn_and_semi.carbon
// CHECK:STDERR: fail_only_fn_and_semi.carbon:[[@LINE+4]]:3: error: `fn` introducer should be followed by a name [ExpectedDeclName]
// CHECK:STDERR: fn;
// CHECK:STDERR: ^
// CHECK:STDERR:
fn;
// --- fail_repeated_fn_and_semi.carbon
// CHECK:STDERR: fail_repeated_fn_and_semi.carbon:[[@LINE+4]]:4: error: `fn` introducer should be followed by a name [ExpectedDeclName]
// CHECK:STDERR: fn fn;
// CHECK:STDERR: ^~
// CHECK:STDERR:
fn fn;
// --- fail_skip_indented_newline_until_outdent.carbon
// CHECK:STDERR: fail_skip_indented_newline_until_outdent.carbon:[[@LINE+4]]:6: error: `fn` introducer should be followed by a name [ExpectedDeclName]
// CHECK:STDERR: fn (x,
// CHECK:STDERR: ^
// CHECK:STDERR:
fn (x,
y,
z)
fn F();
// --- fail_skip_indented_newline_with_semi.carbon
// CHECK:STDERR: fail_skip_indented_newline_with_semi.carbon:[[@LINE+4]]:4: error: `fn` introducer should be followed by a name [ExpectedDeclName]
// CHECK:STDERR: fn (x,
// CHECK:STDERR: ^
// CHECK:STDERR:
fn (x,
y,
z);
fn F();
// --- fail_skip_indented_newline_without_semi.carbon
// CHECK:STDERR: fail_skip_indented_newline_without_semi.carbon:[[@LINE+4]]:4: error: `fn` introducer should be followed by a name [ExpectedDeclName]
// CHECK:STDERR: fn (x,
// CHECK:STDERR: ^
// CHECK:STDERR:
fn (x,
y,
z)
fn F();
// --- fail_skip_to_newline_without_semi.carbon
// CHECK:STDERR: fail_skip_to_newline_without_semi.carbon:[[@LINE+4]]:4: error: `fn` introducer should be followed by a name [ExpectedDeclName]
// CHECK:STDERR: fn ()
// CHECK:STDERR: ^
// CHECK:STDERR:
fn ()
fn F();
// --- fail_skip_without_semi_to_curly.carbon
// CHECK:STDERR: fail_skip_without_semi_to_curly.carbon:[[@LINE+4]]:1: error: unrecognized declaration introducer [UnrecognizedDecl]
// CHECK:STDERR: struct X { fn () }
// CHECK:STDERR: ^~~~~~
// CHECK:STDERR:
struct X { fn () }
fn F();
// --- with_identifier_as_param.carbon
fn foo(bar);
// --- fail_without_name_and_many_tokens_in_params.carbon
// CHECK:STDERR: fail_without_name_and_many_tokens_in_params.carbon:[[@LINE+4]]:4: error: `fn` introducer should be followed by a name [ExpectedDeclName]
// CHECK:STDERR: fn (a tokens c d e f g h i j k l m n o p q r s t u v w x y z);
// CHECK:STDERR: ^
// CHECK:STDERR:
fn (a tokens c d e f g h i j k l m n o p q r s t u v w x y z);
// --- form_parameter.carbon
fn FormParam(x:? Form);
fn ComplexFormParam(x:? X.Y(Z));
// --- fail_ref_on_form_parameter.carbon
// CHECK:STDERR: fail_ref_on_form_parameter.carbon:[[@LINE+4]]:6: error: `ref` is only allowed on a runtime binding [ExpectedRuntimeBindingPatternAfterRef]
// CHECK:STDERR: fn F(ref x:? Form);
// CHECK:STDERR: ^~~
// CHECK:STDERR:
fn F(ref x:? Form);
// --- fail_form_within_var.carbon
// CHECK:STDERR: fail_form_within_var.carbon:[[@LINE+4]]:26: error: found `:?` binding inside `var` pattern [NonRegularBindingInVarDecl]
// CHECK:STDERR: fn FormInVar(var x:? Form);
// CHECK:STDERR: ^
// CHECK:STDERR:
fn FormInVar(var x:? Form);
// --- return_form.carbon
fn SimpleReturnForm() ->? Form;
fn ComplexReturnForm() ->? X.Y(Z);
// --- ref_return.carbon
fn RefReturn() -> ref u32;
fn ComplexRefReturn() -> ref X.Y(Z);
let a: auto = fn -> ref u32 => 0;
// --- fail_ref_return_missing_type.carbon
// CHECK:STDERR: fail_ref_return_missing_type.carbon:[[@LINE+4]]:22: error: expected expression [ExpectedExpr]
// CHECK:STDERR: fn RefReturn() -> ref;
// CHECK:STDERR: ^
// CHECK:STDERR:
fn RefReturn() -> ref;
// CHECK:STDOUT: - filename: basic.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'F'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: ref.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'foo'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ │ │ ╭─IdentifierNameNotBeforeSignature 'a'
// CHECK:STDOUT: │ │ │ ╭─RefBindingName 'ref'
// CHECK:STDOUT: │ │ │ ├─BindingPatternTypeStart ':'
// CHECK:STDOUT: │ │ │ ├─IntTypeLiteral 'i32'
// CHECK:STDOUT: │ │ ├─LetBindingPattern ':'
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: implicit_empty.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'foo'
// CHECK:STDOUT: │ │ ╭─ImplicitParamListStart '['
// CHECK:STDOUT: │ ├─ImplicitParamList ']'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: implicit_params.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'foo'
// CHECK:STDOUT: │ │ ╭─ImplicitParamListStart '['
// CHECK:STDOUT: │ │ │ ╭─IdentifierNameNotBeforeSignature 'a'
// CHECK:STDOUT: │ │ │ ├─CompileTimeBindingPatternTypeStart ':'
// CHECK:STDOUT: │ │ │ ├─IntTypeLiteral 'i32'
// CHECK:STDOUT: │ │ ├─CompileTimeBindingPattern ':'
// CHECK:STDOUT: │ │ ├─PatternListComma ','
// CHECK:STDOUT: │ │ │ ╭─IdentifierNameNotBeforeSignature 'b'
// CHECK:STDOUT: │ │ │ ├─CompileTimeBindingPatternTypeStart ':'
// CHECK:STDOUT: │ │ │ ├─IntTypeLiteral 'i32'
// CHECK:STDOUT: │ │ ├─CompileTimeBindingPattern ':'
// CHECK:STDOUT: │ ├─ImplicitParamList ']'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: no_params.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameNotBeforeSignature 'foo'
// CHECK:STDOUT: │ ╭─FunctionDefinitionStart '{'
// CHECK:STDOUT: ├─FunctionDefinition '}'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: params.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'foo'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ │ │ ╭─IdentifierNameNotBeforeSignature 'a'
// CHECK:STDOUT: │ │ │ ├─BindingPatternTypeStart ':'
// CHECK:STDOUT: │ │ │ ├─IntTypeLiteral 'i32'
// CHECK:STDOUT: │ │ ├─LetBindingPattern ':'
// CHECK:STDOUT: │ │ ├─PatternListComma ','
// CHECK:STDOUT: │ │ │ ╭─IdentifierNameNotBeforeSignature 'b'
// CHECK:STDOUT: │ │ │ ├─BindingPatternTypeStart ':'
// CHECK:STDOUT: │ │ │ ├─IntTypeLiteral 'i32'
// CHECK:STDOUT: │ │ ├─LetBindingPattern ':'
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: with_return_type.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'foo'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: │ │ ╭─UnsignedIntTypeLiteral 'u32'
// CHECK:STDOUT: │ ├─ReturnType '->'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: impl_fn.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─OverrideModifier 'override'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'F'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─AbstractModifier 'abstract'
// CHECK:STDOUT: │ ├─OverrideModifier 'override'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'G'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─OverrideModifier 'override'
// CHECK:STDOUT: │ ├─AbstractModifier 'abstract'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'H'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─PrivateModifier 'private'
// CHECK:STDOUT: │ ├─OverrideModifier 'override'
// CHECK:STDOUT: │ ├─DefaultModifier 'default'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'I'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_identifier_instead_of_sig.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameNotBeforeSignature 'foo'
// CHECK:STDOUT: ├─FunctionDecl ';' has_error
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_missing_implicit_close.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'Div'
// CHECK:STDOUT: │ │ ╭─ImplicitParamListStart '['
// CHECK:STDOUT: │ │ │ ╭─TuplePatternStart '('
// CHECK:STDOUT: │ │ ├─TuplePattern ')'
// CHECK:STDOUT: │ ├─ImplicitParamList ']'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_missing_name.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─InvalidParse '(' has_error
// CHECK:STDOUT: ├─FunctionDecl ';' has_error
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_no_sig_or_semi.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameNotBeforeSignature 'foo'
// CHECK:STDOUT: ├─FunctionDecl 'fn' has_error
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_only_fn_and_semi.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─InvalidParse ';' has_error
// CHECK:STDOUT: ├─FunctionDecl ';' has_error
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_repeated_fn_and_semi.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─InvalidParse 'fn' has_error
// CHECK:STDOUT: ├─FunctionDecl ';' has_error
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_skip_indented_newline_until_outdent.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─InvalidParse '(' has_error
// CHECK:STDOUT: ├─FunctionDecl ')' has_error
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'F'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_skip_indented_newline_with_semi.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─InvalidParse '(' has_error
// CHECK:STDOUT: ├─FunctionDecl ';' has_error
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'F'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_skip_indented_newline_without_semi.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─InvalidParse '(' has_error
// CHECK:STDOUT: ├─FunctionDecl ')' has_error
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'F'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_skip_to_newline_without_semi.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─InvalidParse '(' has_error
// CHECK:STDOUT: ├─FunctionDecl ')' has_error
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'F'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_skip_without_semi_to_curly.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─InvalidParseStart 'struct' has_error
// CHECK:STDOUT: ├─InvalidParseSubtree '}' has_error
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'F'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: with_identifier_as_param.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'foo'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ │ ├─IdentifierNameExpr 'bar'
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_without_name_and_many_tokens_in_params.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─InvalidParse '(' has_error
// CHECK:STDOUT: ├─FunctionDecl ';' has_error
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: form_parameter.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'FormParam'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ │ │ ╭─IdentifierNameNotBeforeSignature 'x'
// CHECK:STDOUT: │ │ │ ├─BindingPatternTypeStart ':?'
// CHECK:STDOUT: │ │ │ ├─IdentifierNameExpr 'Form'
// CHECK:STDOUT: │ │ ├─FormBindingPattern ':?'
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'ComplexFormParam'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ │ │ ╭─IdentifierNameNotBeforeSignature 'x'
// CHECK:STDOUT: │ │ │ ├─BindingPatternTypeStart ':?'
// CHECK:STDOUT: │ │ │ │ ╭─IdentifierNameExpr 'X'
// CHECK:STDOUT: │ │ │ │ ├─IdentifierNameNotBeforeSignature 'Y'
// CHECK:STDOUT: │ │ │ │ ╭─MemberAccessExpr '.'
// CHECK:STDOUT: │ │ │ │ ╭─CallExprStart '('
// CHECK:STDOUT: │ │ │ │ ├─IdentifierNameExpr 'Z'
// CHECK:STDOUT: │ │ │ ├─CallExpr ')'
// CHECK:STDOUT: │ │ ├─FormBindingPattern ':?'
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_ref_on_form_parameter.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'F'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ │ │ ╭─IdentifierNameNotBeforeSignature 'x'
// CHECK:STDOUT: │ │ │ ├─BindingPatternTypeStart ':?' has_error
// CHECK:STDOUT: │ │ │ ├─IdentifierNameExpr 'Form'
// CHECK:STDOUT: │ │ ├─FormBindingPattern ':?' has_error
// CHECK:STDOUT: │ ├─ExplicitParamList ')' has_error
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_form_within_var.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'FormInVar'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ │ │ ╭─IdentifierNameNotBeforeSignature 'x'
// CHECK:STDOUT: │ │ │ ├─BindingPatternTypeStart ':?'
// CHECK:STDOUT: │ │ │ ├─IdentifierNameExpr 'Form'
// CHECK:STDOUT: │ │ │ ╭─VarBindingPattern ':?' has_error
// CHECK:STDOUT: │ │ ├─VariablePattern 'var' has_error
// CHECK:STDOUT: │ ├─ExplicitParamList ')' has_error
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: return_form.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'SimpleReturnForm'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: │ │ ╭─IdentifierNameExpr 'Form'
// CHECK:STDOUT: │ ├─ReturnForm '->?'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'ComplexReturnForm'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: │ │ ╭─IdentifierNameExpr 'X'
// CHECK:STDOUT: │ │ ├─IdentifierNameNotBeforeSignature 'Y'
// CHECK:STDOUT: │ │ ╭─MemberAccessExpr '.'
// CHECK:STDOUT: │ │ ╭─CallExprStart '('
// CHECK:STDOUT: │ │ ├─IdentifierNameExpr 'Z'
// CHECK:STDOUT: │ │ ╭─CallExpr ')'
// CHECK:STDOUT: │ ├─ReturnForm '->?'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: ref_return.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'RefReturn'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: │ │ ╭─UnsignedIntTypeLiteral 'u32'
// CHECK:STDOUT: │ │ ╭─RefPrimitiveForm 'ref'
// CHECK:STDOUT: │ ├─ReturnType '->'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'ComplexRefReturn'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: │ │ ╭─IdentifierNameExpr 'X'
// CHECK:STDOUT: │ │ ├─IdentifierNameNotBeforeSignature 'Y'
// CHECK:STDOUT: │ │ ╭─MemberAccessExpr '.'
// CHECK:STDOUT: │ │ ╭─CallExprStart '('
// CHECK:STDOUT: │ │ ├─IdentifierNameExpr 'Z'
// CHECK:STDOUT: │ │ ╭─CallExpr ')'
// CHECK:STDOUT: │ │ ╭─RefPrimitiveForm 'ref'
// CHECK:STDOUT: │ ├─ReturnType '->'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: │ ╭─LetIntroducer 'let'
// CHECK:STDOUT: │ │ ╭─IdentifierNameNotBeforeSignature 'a'
// CHECK:STDOUT: │ │ ├─BindingPatternTypeStart ':'
// CHECK:STDOUT: │ │ ├─AutoTypeLiteral 'auto'
// CHECK:STDOUT: │ ├─LetBindingPattern ':'
// CHECK:STDOUT: │ ├─LetInitializer '='
// CHECK:STDOUT: │ │ ╭─LambdaIntroducer 'fn'
// CHECK:STDOUT: │ │ │ ╭─UnsignedIntTypeLiteral 'u32'
// CHECK:STDOUT: │ │ │ ╭─PrefixOperatorRef 'ref'
// CHECK:STDOUT: │ │ ├─ReturnType '->'
// CHECK:STDOUT: │ │ ╭─LambdaDefinitionStart '=>'
// CHECK:STDOUT: │ │ ├─IntLiteral '0'
// CHECK:STDOUT: │ ├─Lambda 'fn'
// CHECK:STDOUT: ├─LetDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)
// CHECK:STDOUT: - filename: fail_ref_return_missing_type.carbon
// CHECK:STDOUT: ╭─FileStart ''
// CHECK:STDOUT: │ ╭─FunctionIntroducer 'fn'
// CHECK:STDOUT: │ ├─IdentifierNameMaybeBeforeSignature 'RefReturn'
// CHECK:STDOUT: │ │ ╭─ExplicitParamListStart '('
// CHECK:STDOUT: │ ├─ExplicitParamList ')'
// CHECK:STDOUT: │ │ ╭─InvalidParse ';' has_error
// CHECK:STDOUT: │ │ ╭─RefPrimitiveForm 'ref' has_error
// CHECK:STDOUT: │ ├─ReturnType '->'
// CHECK:STDOUT: ├─FunctionDecl ';'
// CHECK:STDOUT: ├─FileEnd ''
// CHECK:STDOUT: (root)