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https://github.com/carbon-language/carbon-lang.git
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Chandler Carruth
8be274cf60
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
145 lines
5.3 KiB
Plaintext
145 lines
5.3 KiB
Plaintext
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/full.carbon
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//
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// AUTOUPDATE
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// TIP: To test this file alone, run:
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// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/primitives/float_conversions.carbon
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// TIP: To dump output, run:
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// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/primitives/float_conversions.carbon
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// --- test_helpers.carbon
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library "[[@TEST_NAME]]";
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class Expect[T: type](N: T) {}
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fn Test[T: type](generic N: T) -> Expect(N) { return {}; }
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// --- literal_conversions.carbon
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library "[[@TEST_NAME]]";
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let _: f32 = 1.25;
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let _: Core.FloatLiteral = 42;
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let _: Core.IntLiteral = 42.0 unsafe as Core.IntLiteral;
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// --- int_to_float.carbon
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library "[[@TEST_NAME]]";
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import library "test_helpers";
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fn F(x: i32, y: u32) {
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let _: f64 = x;
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let _: f64 = y;
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Test(12345 as f32) as Expect(12345.0 as f32);
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Test(-42 as f64) as Expect(-(42.0 as f64));
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}
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// --- int_literal_to_float.carbon
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library "[[@TEST_NAME]]";
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fn F() {
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let _: f32 = 42;
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let _: f64 = 1234567890123456;
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}
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// --- fail_int_literal_to_float_lossy.carbon
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library "[[@TEST_NAME]]";
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// CHECK:STDERR: fail_int_literal_to_float_lossy.carbon:[[@LINE+4]]:14: error: integer value 123456789 cannot be represented exactly in floating-point type `f32` [IntLossyConversionToFloat]
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// CHECK:STDERR: let a: f32 = 123456789;
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// CHECK:STDERR: ^~~~~~~~~
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// CHECK:STDERR:
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let a: f32 = 123456789;
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// CHECK:STDERR: fail_int_literal_to_float_lossy.carbon:[[@LINE+4]]:14: error: integer value 100000001 cannot be represented exactly in floating-point type `f32` [IntLossyConversionToFloat]
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// CHECK:STDERR: let b: f32 = 100000001;
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// CHECK:STDERR: ^~~~~~~~~
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// CHECK:STDERR:
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let b: f32 = 100000001;
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// CHECK:STDERR: fail_int_literal_to_float_lossy.carbon:[[@LINE+4]]:14: error: integer value 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 too large for floating-point type `f32` [IntTooLargeForFloatType]
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// CHECK:STDERR: let c: f32 = 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000;
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR:
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let c: f32 = 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000;
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// --- float_unsafe_as_int.carbon
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library "[[@TEST_NAME]]";
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import library "test_helpers";
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fn F() {
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// Float literal to Sized Integer explicit conversion via `unsafe as`.
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Test(12.34 unsafe as i32) as Expect(12 as i32);
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Test(42.0 unsafe as u32) as Expect(42 as u32);
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// Negative float to signed integer.
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// TODO: Also test converting a negative float literal once they are
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// supported.
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Test(-(1.99 as f64) unsafe as i8) as Expect(-1 as i8);
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// Float literal to int literal.
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Test(123.45 unsafe as Core.IntLiteral) as Expect(123);
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}
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// --- fail_float_as_int.carbon
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library "[[@TEST_NAME]]";
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import library "test_helpers";
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fn F(f: f32) {
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// Lossy explicit conversion using `as` not permitted.
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// CHECK:STDERR: fail_float_as_int.carbon:[[@LINE+7]]:16: error: cannot convert expression of type `Core.FloatLiteral` to `i32` with `as` [ConversionFailure]
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// CHECK:STDERR: let _: i32 = 12.34 as i32;
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// CHECK:STDERR: ^~~~~~~~~~~~
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// CHECK:STDERR: fail_float_as_int.carbon:[[@LINE+4]]:16: note: type `Core.FloatLiteral` does not implement interface `Core.As(i32)` [MissingImplInMemberAccessInContext]
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// CHECK:STDERR: let _: i32 = 12.34 as i32;
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// CHECK:STDERR: ^~~~~~~~~~~~
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// CHECK:STDERR:
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let _: i32 = 12.34 as i32;
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// CHECK:STDERR: fail_float_as_int.carbon:[[@LINE+7]]:16: error: cannot convert expression of type `f32` to `i32` with `as` [ConversionFailure]
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// CHECK:STDERR: let _: i32 = f as i32;
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// CHECK:STDERR: ^~~~~~~~
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// CHECK:STDERR: fail_float_as_int.carbon:[[@LINE+4]]:16: note: type `f32` does not implement interface `Core.As(i32)` [MissingImplInMemberAccessInContext]
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// CHECK:STDERR: let _: i32 = f as i32;
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// CHECK:STDERR: ^~~~~~~~
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// CHECK:STDERR:
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let _: i32 = f as i32;
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}
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// --- float_to_float.carbon
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library "[[@TEST_NAME]]";
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import library "test_helpers";
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fn F(x: f32) {
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// Implicit conversion (widening f32 -> f64)
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let y: f64 = x;
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// Explicit conversion (widening f32 -> f64)
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let _: f64 = x as f64;
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// Explicit conversion (narrowing f64 -> f32)
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let _: f32 = y as f32;
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}
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// --- fail_float_to_float_narrowing.carbon
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library "[[@TEST_NAME]]";
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fn F(x: f64) {
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// Implicit narrowing conversion (f64 -> f32) is not permitted.
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// CHECK:STDERR: fail_float_to_float_narrowing.carbon:[[@LINE+7]]:16: error: cannot implicitly convert expression of type `f64` to `f32` [ConversionFailure]
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// CHECK:STDERR: let _: f32 = x;
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// CHECK:STDERR: ^
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// CHECK:STDERR: fail_float_to_float_narrowing.carbon:[[@LINE+4]]:16: note: type `f64` does not implement interface `Core.ImplicitAs(f32)` [MissingImplInMemberAccessInContext]
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// CHECK:STDERR: let _: f32 = x;
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// CHECK:STDERR: ^
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// CHECK:STDERR:
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let _: f32 = x;
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}
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