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refactor(fe): centralize use-before-declaration checking
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Put all use-before-declaration error checking into
report_errors_for_variable_use and
report_error_if_assignment_is_illegal.
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@strager
strager committed Nov 21, 2023
1 parent df1cb1e commit 1c03c4f
Showing 1 changed file with 69 additions and 59 deletions.
128 changes: 69 additions & 59 deletions src/quick-lint-js/fe/variable-analyzer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -326,57 +326,8 @@ void Variable_Analyzer::declare_variable(Scope &scope, Identifier name,
return false;
}
declared.is_used = true;
if (kind == Variable_Kind::_function &&
declared_scope ==
Declared_Variable_Scope::declared_in_descendant_scope &&
used_var.kind == Used_Variable_Kind::use) {
this->diag_reporter_->report(
Diag_Function_Call_Before_Declaration_In_Block_Scope{
.use = used_var.name.span(),
.declaration = name.span(),
});
}
this->report_errors_for_variable_use(
used_var, declared,
/*use_is_before_declaration=*/kind == Variable_Kind::_class ||
kind == Variable_Kind::_const || kind == Variable_Kind::_let);
if (this->in_typescript_ambient_context()) {
// Use before declaration is allowed in ambient contexts. For example:
//
// new C(); // OK
// declare class C {} // OK (we are here)
} else {
switch (used_var.kind) {
case Used_Variable_Kind::assignment:
break;
case Used_Variable_Kind::_export_default:
case Used_Variable_Kind::_typeof:
case Used_Variable_Kind::use:
if (kind == Variable_Kind::_class || kind == Variable_Kind::_const ||
kind == Variable_Kind::_let) {
this->diag_reporter_->report(Diag_Variable_Used_Before_Declaration{
.use = used_var.name.span(),
.declaration = name.span(),
});
}
break;
case Used_Variable_Kind::_delete:
// Use before declaration is legal for delete.
break;
case Used_Variable_Kind::_export:
// Use before declaration is legal for variable exports.
break;
case Used_Variable_Kind::type:
if (kind == Variable_Kind::_generic_parameter) {
this->diag_reporter_->report(Diag_Variable_Used_Before_Declaration{
.use = used_var.name.span(),
.declaration = name.span(),
});
}
// Use before declaration is normally legal for types.
break;
}
}
this->report_errors_for_variable_use(used_var, declared,
/*use_is_before_declaration=*/true);
return true;
});
erase_if(scope.variables_used_in_descendant_scope,
Expand Down Expand Up @@ -882,16 +833,8 @@ void Variable_Analyzer::report_error_if_assignment_is_illegal(

QLJS_WARNING_POP
break;
case Variable_Kind::_arrow_parameter:
case Variable_Kind::_catch:
case Variable_Kind::_class:
case Variable_Kind::_function:
case Variable_Kind::_function_parameter:
case Variable_Kind::_function_type_parameter:
// FIXME(strager): Is _index_signature_parameter correct here?
case Variable_Kind::_index_signature_parameter:
case Variable_Kind::_let:
case Variable_Kind::_var:
if (is_assigned_before_declaration) {
QLJS_WARNING_PUSH
QLJS_WARNING_IGNORE_GCC("-Wnull-dereference")
Expand All @@ -904,6 +847,19 @@ void Variable_Analyzer::report_error_if_assignment_is_illegal(
QLJS_WARNING_POP
}
break;
// FIXME(strager): Assigning to an arrow or function parameter before
// declaration is not legal.
case Variable_Kind::_arrow_parameter:
case Variable_Kind::_catch:
case Variable_Kind::_function:
case Variable_Kind::_function_parameter:
// FIXME(strager): Assigning to a type parameter cannot happen.
case Variable_Kind::_function_type_parameter:
// FIXME(strager): Is _index_signature_parameter correct here?
case Variable_Kind::_index_signature_parameter:
case Variable_Kind::_var:
// Use before declaration is okay.
break;
case Variable_Kind::_interface:
// Interfaces can't be assigned to.
QLJS_UNREACHABLE();
Expand Down Expand Up @@ -954,6 +910,60 @@ void Variable_Analyzer::report_errors_for_variable_use(
used_var.name.span().end()),
});
}

if constexpr (!declared_in_global_scope) {
if (declared.kind == Variable_Kind::_function &&
declared.declaration_scope ==
Declared_Variable_Scope::declared_in_descendant_scope &&
used_var.kind == Used_Variable_Kind::use) {
this->diag_reporter_->report(
Diag_Function_Call_Before_Declaration_In_Block_Scope{
.use = used_var.name.span(),
.declaration = declared.declaration.span(),
});
}

if (use_is_before_declaration) {
if (this->in_typescript_ambient_context()) {
// Use before declaration is allowed in ambient contexts. For example:
//
// new C(); // OK
// declare class C {} // OK (we are here)
} else {
switch (used_var.kind) {
case Used_Variable_Kind::assignment:
break;
case Used_Variable_Kind::_export_default:
case Used_Variable_Kind::_typeof:
case Used_Variable_Kind::use:
if (declared.kind == Variable_Kind::_class ||
declared.kind == Variable_Kind::_const ||
declared.kind == Variable_Kind::_let) {
this->diag_reporter_->report(Diag_Variable_Used_Before_Declaration{
.use = used_var.name.span(),
.declaration = declared.declaration.span(),
});
}
break;
case Used_Variable_Kind::_delete:
// Use before declaration is legal for delete.
break;
case Used_Variable_Kind::_export:
// Use before declaration is legal for variable exports.
break;
case Used_Variable_Kind::type:
if (declared.kind == Variable_Kind::_generic_parameter) {
this->diag_reporter_->report(Diag_Variable_Used_Before_Declaration{
.use = used_var.name.span(),
.declaration = declared.declaration.span(),
});
}
// Use before declaration is normally legal for types.
break;
}
}
}
}
}

void Variable_Analyzer::report_error_if_variable_declaration_conflicts_in_scope(
Expand Down

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