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Add diagnostics for bad semicolons errors, closes #352 #362

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Merged
merged 6 commits into from
Apr 20, 2023
Merged

Add diagnostics for bad semicolons errors, closes #352 #362

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8b8e409
Add diagnostics for semicolon at the end of function
filipsajdak Apr 20, 2023
d1e4c64
Add diagnostics for semicolon at the end of for loop
filipsajdak Apr 20, 2023
120f87b
Add diagnostics for semicolon at the end of while body
filipsajdak Apr 20, 2023
03a9baa
Add diagnostics for double semicolon at short lambda
filipsajdak Apr 20, 2023
179b953
Add diagnostics for empty statements (extra semicolon)
filipsajdak Apr 20, 2023
6881f5b
Fix error() method that throws when done() is true
filipsajdak Apr 20, 2023
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48 changes: 42 additions & 6 deletions source/parse.h
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Original file line number Diff line number Diff line change
Expand Up @@ -3068,15 +3068,15 @@ class parser
-> void
{
auto m = std::string{msg};
auto i = done() ? -1 : 0;
assert (peek(i));
if (include_curr_token) {
m += std::string(" (at '") + curr().to_string(true) + "')";
m += std::string(" (at '") + peek(i)->to_string(true) + "')";
}
if (
err_pos == source_position{}
&& peek(0)
)
{
err_pos = peek(0)->position();
) {
err_pos = peek(i)->position();
}
errors.emplace_back( err_pos, m, false, fallback );
}
Expand Down Expand Up @@ -3225,6 +3225,12 @@ class parser
next();
return {};
}
if ( // check if a single-expression function is followed by an extra second semicolon
decl->initializer && decl->initializer->is_expression()
&& !done() && curr().type() == lexeme::Semicolon
) {
error("a single-expression function should end with a single semicolon");
}
if (!(*func)->contracts.empty()) {
error("an unnamed function at expression scope currently cannot have contracts");
next();
Expand Down Expand Up @@ -4423,6 +4429,10 @@ class parser
if (!handle_logical_expression ()) { return {}; }
if (!handle_optional_next_clause()) { return {}; }
if (!handle_compound_statement ()) { return {}; }
if (!done() && curr().type() == lexeme::Semicolon) {
error("a loop body may not be followed by a semicolon (empty statements are not allowed)");
return {};
}
return n;
}

Expand Down Expand Up @@ -4485,6 +4495,11 @@ class parser
n->for_with_in = true;
}

if (!done() && curr().type() == lexeme::Semicolon) {
error("a loop body may not be followed by a semicolon (empty statements are not allowed)");
return {};
}

return n;
}

Expand Down Expand Up @@ -4707,6 +4722,11 @@ class parser
)
-> std::unique_ptr<statement_node>
{
if (!done() && curr().type() == lexeme::Semicolon) {
error("empty statement is not allowed - remove extra semicolon");
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I think this works, but just a note: Emitting an error here (not just returning null) could interfere with productions where statement is one alternative but where if it doesn't parse as a statement we would want to try other fallback production(s) instead. I don't think that actually happens today in the grammar though, so this should be okay.

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@hsutter hsutter Apr 20, 2023 •
edited
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Basically, the scenario would be "is there any production where a statement could appear, where if it's not a statement something else that starts with a ; could appear instead" -- I think there isn't today so it should be safe to reject a ; if we're in a position where a statement could appear

return {};
}

auto n = std::make_unique<statement_node>();

// Now handle the rest of the statement
Expand Down Expand Up @@ -5073,7 +5093,8 @@ class parser

// If there's no [ [ then this isn't a contract
if (
curr().type() != lexeme::LeftBracket
done()
|| curr().type() != lexeme::LeftBracket
|| !peek(1)
|| peek(1)->type() != lexeme::LeftBracket
)
Expand Down Expand Up @@ -5690,6 +5711,21 @@ class parser
return {};
}

if (
n->is_function()
&& n->initializer
&& !done() && curr().type() == lexeme::Semicolon
)
{
if (n->initializer->is_compound() && n->has_name()) {
error("a braced function body may not be followed by a semicolon (empty statements are not allowed)");
return {};
} else if (n->initializer->is_expression()) {
error("a single-expression function should end with a single semicolon");
return {};
}
}

// If this is an implicit constructor, it must have two parameters
if (n->is_constructor())
{
Expand Down