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(GRAM): allow empty type parameter lists
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This is valid Rust:
rust-lang/rust#32023
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@matklad
matklad committed Mar 9, 2016
1 parent 07a4fb5 commit 5b033c9
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Showing 4 changed files with 277 additions and 6 deletions.
7 changes: 1 addition & 6 deletions src/main/kotlin/org/rust/lang/core/grammar/rust.bnf
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Expand Up @@ -370,12 +370,7 @@ generic_params ::= [ generic_params_inner ]

private generic_params_inner ::= LT lifetimes [ COMMA [ type_params COMMA? ] ] GT
| LT type_params COMMA? GT
/* | LT lifetimes GTGT
| LT lifetimes COMMA GTGT */
/* | LT lifetimes COMMA type_params GTGT
| LT lifetimes COMMA type_params COMMA GTGT */
/* | LT type_params SHR
| LT type_params COMMA SHR */
| LT GT

lifetimes ::= lifetime_and_bounds (COMMA lifetime_and_bounds)*

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1 change: 1 addition & 0 deletions src/test/kotlin/org/rust/lang/core/parser/RustCompleteParsingTestCase.kt
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Expand Up @@ -30,5 +30,6 @@ class RustCompleteParsingTestCase : RustParsingTestCaseBase("well-formed") {
fun testSuperPaths() = doTest(true)
fun testPrecedence() = doTest(true)
fun testWayTooManyParens() = doTest(true)
fun testEmptyGenerics() = doTest(true)
// @formatter:on
}
23 changes: 23 additions & 0 deletions src/test/resources/org/rust/lang/core/parser/fixtures/well-formed/empty_generics.rs
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@@ -0,0 +1,23 @@
// Test that empty type parameter list (<>) is synonymous with
// no type parameters at all

struct S<>;
trait T<> {}
enum E<> { V }
impl<> T<> for S<> {}
impl T for E {}
fn foo<>() {}
fn bar() {}

fn main() {
let _ = S;
let _ = S::<>;
let _ = E::V;
let _ = E::<>::V;
foo();
foo::<>();

// Test that we can supply <> to non generic things
bar::<>();
let _: i32<>;
}
252 changes: 252 additions & 0 deletions src/test/resources/org/rust/lang/core/parser/fixtures/well-formed/empty_generics.txt
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@@ -0,0 +1,252 @@
FILE
PsiComment(<EOL_COMMENT>)('// Test that empty type parameter list (<>) is synonymous with')
PsiWhiteSpace('\n')
PsiComment(<EOL_COMMENT>)('// no type parameters at all')
PsiWhiteSpace('\n\n')
RustFileModItemImpl(FILE_MOD_ITEM)
RustStructItemImpl(STRUCT_ITEM)
PsiElement(struct)('struct')
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RustGenericParamsImpl(GENERIC_PARAMS)
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RustGenericParamsImpl(GENERIC_PARAMS)
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RustEnumItemImpl(ENUM_ITEM)
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RustGenericParamsImpl(GENERIC_PARAMS)
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RustGenericArgsImpl(GENERIC_ARGS)
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RustGenericArgsImpl(GENERIC_ARGS)
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<empty list>
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RustGenericParamsImpl(GENERIC_PARAMS)
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PsiElement(()('(')
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<empty list>
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PsiElement(<IDENTIFIER>)('E')
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