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Start avoiding parse diagnostics on error tokens (#4431)

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An invalid parse due to an error token isn't likely a great diagnostic
as it will already have been diagnosed by the lexer. A common case to
start handling that is when the parser encounters an invalid token when
expecting an expression.

This removes a number of unhelpful diagnostics after the lexer has done
a good job diagnosing.

This also means that there may be parse tree errors that aren't
diagnosed when there are lexer-diagnosed errors, so track that.

Follow-up to #4430 that almost finishes addressing its diagnostic TODO.
This commit is contained in:
Chandler Carruth
2024-11-02 05:53:27 +00:00
committed by GitHub
parent 44fe65fbe5
commit 1b2eb42c5a
5 changed files with 15 additions and 32 deletions
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toolchain/check/testdata/basics/type_literals.carbon
Vendored
-8
View File
@@ -39,10 +39,6 @@ var test_i15: i15;
// CHECK:STDERR:
var test_i1000000000: i1000000000;
// TODO: This diagnostic is not very good.
// CHECK:STDERR: fail_iN_bad_width.carbon:[[@LINE+12]]:33: error: expected expression [ExpectedExpr]
// CHECK:STDERR: var test_i10000000000000000000: i10000000000000000000;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
// CHECK:STDERR: fail_iN_bad_width.carbon:[[@LINE+8]]:33: error: semantics TODO: `HandleInvalidParse` [SemanticsTodo]
// CHECK:STDERR: var test_i10000000000000000000: i10000000000000000000;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~
@@ -84,10 +80,6 @@ var test_u15: u15;
// CHECK:STDERR:
var test_u1000000000: u1000000000;
// TODO: This diagnostic is not very good.
// CHECK:STDERR: fail_uN_bad_width.carbon:[[@LINE+12]]:33: error: expected expression [ExpectedExpr]
// CHECK:STDERR: var test_u10000000000000000000: u10000000000000000000;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
// CHECK:STDERR: fail_uN_bad_width.carbon:[[@LINE+8]]:33: error: semantics TODO: `HandleInvalidParse` [SemanticsTodo]
// CHECK:STDERR: var test_u10000000000000000000: u10000000000000000000;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~
toolchain/parse/handle_expr.cpp
+7 -3
View File
@@ -73,7 +73,7 @@ auto HandleExprInPostfix(Context& context) -> void {
// Parses a primary expression, which is either a terminal portion of an
// expression tree, such as an identifier or literal, or a parenthesized
// expression.
switch (context.PositionKind()) {
switch (auto token_kind = context.PositionKind()) {
case Lex::TokenKind::Identifier: {
context.AddLeafNode(NodeKind::IdentifierNameExpr, context.Consume());
context.PushState(state);
@@ -208,11 +208,15 @@ auto HandleExprInPostfix(Context& context) -> void {
break;
}
default: {
// If not already diagnosed in the lexer, diagnose it here.
if (token_kind != Lex::TokenKind::Error) {
CARBON_DIAGNOSTIC(ExpectedExpr, Error, "expected expression");
context.emitter().Emit(*context.position(), ExpectedExpr);
}
// Add a node to keep the parse tree balanced.
context.AddLeafNode(NodeKind::InvalidParse, *context.position(),
/*has_error=*/true);
CARBON_DIAGNOSTIC(ExpectedExpr, Error, "expected expression");
context.emitter().Emit(*context.position(), ExpectedExpr);
context.ReturnErrorOnState();
break;
}
toolchain/parse/parse.cpp
+4 -1
View File
@@ -45,7 +45,10 @@ auto Parse(Lex::TokenizedBuffer& tokens, DiagnosticConsumer& consumer,
}
context.AddLeafNode(NodeKind::FileEnd, *context.position());
tree.set_has_errors(err_tracker.seen_error());
// Mark the tree as potentially having errors if there were errors coming in
// from the tokenized buffer or we diagnosed new errors.
tree.set_has_errors(tokens.has_errors() || err_tracker.seen_error());
if (auto verify = tree.Verify(); !verify.ok()) {
// TODO: This is temporarily printing to stderr directly during development.
toolchain/parse/testdata/array/fail_require_close_bracket.carbon
Vendored
+1 -5
View File
@@ -9,11 +9,7 @@
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/parse/testdata/array/fail_require_close_bracket.carbon
// TODO: It should emit only one error message.
// CHECK:STDERR: fail_require_close_bracket.carbon:[[@LINE+7]]:8: error: opening symbol without a corresponding closing symbol [UnmatchedOpening]
// CHECK:STDERR: var x: [i32;;
// CHECK:STDERR: ^
// CHECK:STDERR:
// CHECK:STDERR: fail_require_close_bracket.carbon:[[@LINE+3]]:8: error: expected expression [ExpectedExpr]
// CHECK:STDERR: fail_require_close_bracket.carbon:[[@LINE+3]]:8: error: opening symbol without a corresponding closing symbol [UnmatchedOpening]
// CHECK:STDERR: var x: [i32;;
// CHECK:STDERR: ^
var x: [i32;;
toolchain/parse/testdata/array/fail_syntax.carbon
Vendored
+3 -15
View File
@@ -38,19 +38,11 @@ fn X() -> [:];
// --- fail_unlexed_expr.carbon
// CHECK:STDERR: fail_unlexed_expr.carbon:[[@LINE+20]]:9: error: encountered unrecognized characters while parsing [UnrecognizedCharacters]
// CHECK:STDERR: fail_unlexed_expr.carbon:[[@LINE+12]]:9: error: encountered unrecognized characters while parsing [UnrecognizedCharacters]
// CHECK:STDERR: var y: [`];
// CHECK:STDERR: ^
// CHECK:STDERR:
// CHECK:STDERR: fail_unlexed_expr.carbon:[[@LINE+16]]:9: error: expected expression [ExpectedExpr]
// CHECK:STDERR: var y: [`];
// CHECK:STDERR: ^
// CHECK:STDERR:
// CHECK:STDERR: fail_unlexed_expr.carbon:[[@LINE+12]]:9: error: expected `;` in array type [ExpectedArraySemi]
// CHECK:STDERR: var y: [`];
// CHECK:STDERR: ^
// CHECK:STDERR:
// CHECK:STDERR: fail_unlexed_expr.carbon:[[@LINE+8]]:9: error: expected expression [ExpectedExpr]
// CHECK:STDERR: fail_unlexed_expr.carbon:[[@LINE+8]]:9: error: expected `;` in array type [ExpectedArraySemi]
// CHECK:STDERR: var y: [`];
// CHECK:STDERR: ^
// CHECK:STDERR:
@@ -62,11 +54,7 @@ var y: [`];
// --- fail_no_close_bracket.carbon
// CHECK:STDERR: fail_no_close_bracket.carbon:[[@LINE+8]]:8: error: opening symbol without a corresponding closing symbol [UnmatchedOpening]
// CHECK:STDERR: var x: [i32;;
// CHECK:STDERR: ^
// CHECK:STDERR:
// CHECK:STDERR: fail_no_close_bracket.carbon:[[@LINE+4]]:8: error: expected expression [ExpectedExpr]
// CHECK:STDERR: fail_no_close_bracket.carbon:[[@LINE+4]]:8: error: opening symbol without a corresponding closing symbol [UnmatchedOpening]
// CHECK:STDERR: var x: [i32;;
// CHECK:STDERR: ^
// CHECK:STDERR: