Diagnose more invalid uses of @_section/@_used

Author: kubamracek

include/swift/AST/DiagnosticsParse.def

@@ -1541,11 +1541,6 @@ ERROR(attr_expected_colon_after_label,none,
 ERROR(alignment_must_be_positive_integer,none,
       "alignment value must be a positive integer literal", ())
 
-ERROR(attr_only_at_non_local_scope, none,
-      "attribute '%0' can only be used in a non-local scope", (StringRef))
-ERROR(attr_only_at_non_generic_scope, none,
-      "attribute '%0' cannot be used in a generic context", (StringRef))
-
 // Access control
 ERROR(attr_access_expected_set,none,
       "expected 'set' as subject of '%0' modifier", (StringRef))

include/swift/AST/DiagnosticsSema.def

@@ -1922,6 +1922,13 @@ ERROR(attr_methods_only,none,
 ERROR(attr_decl_async,none,
       "@%0 %1 cannot be asynchronous", (StringRef, DescriptiveDeclKind))
 
+ERROR(attr_only_at_non_local_scope, none,
+      "attribute '%0' can only be used in a non-local scope", (StringRef))
+ERROR(attr_only_at_non_generic_scope, none,
+      "attribute '%0' cannot be used in a generic context", (StringRef))
+ERROR(attr_only_on_static_properties, none,
+      "properties with attribute '_section' must be static", (StringRef))
+
 ERROR(access_control_in_protocol,none,
       "%0 modifier cannot be used in protocols", (DeclAttribute))
 NOTE(access_control_in_protocol_detail,none,
@@ -3739,6 +3746,8 @@ ERROR(attr_not_on_variadic_parameters,none,
       "'%0' must not be used on variadic parameters", (StringRef))
 ERROR(attr_not_on_stored_properties,none,
       "'%0' must not be used on stored properties", (DeclAttribute))
+ERROR(attr_not_on_computed_properties,none,
+      "'%0' must not be used on computed properties", (DeclAttribute))
 
 WARNING(attr_has_no_effect_on_decl_with_access_level,none,
        "'%0' does not have any effect on "

lib/Parse/ParseDecl.cpp

@@ -20,6 +20,7 @@
 #include "swift/AST/DebuggerClient.h"
 #include "swift/AST/Decl.h"
 #include "swift/AST/DiagnosticsParse.h"
+#include "swift/AST/DiagnosticsSema.h"
 #include "swift/AST/GenericParamList.h"
 #include "swift/AST/Initializer.h"
 #include "swift/AST/LazyResolver.h"

lib/Sema/TypeCheckAttr.cpp

@@ -2084,10 +2084,18 @@ void AttributeChecker::visitUsedAttr(UsedAttr *attr) {
   if (D->getDeclContext()->isLocalContext())
     diagnose(attr->getLocation(), diag::attr_only_at_non_local_scope,
              attr->getAttrName());
-
-  if (D->getDeclContext()->isGenericContext())
+  else if (D->getDeclContext()->isGenericContext())
     diagnose(attr->getLocation(), diag::attr_only_at_non_generic_scope,
              attr->getAttrName());
+  else if (auto *VarD = dyn_cast<VarDecl>(D)) {
+    if (!VarD->isStatic() && !D->getDeclContext()->isModuleScopeContext()) {
+      diagnose(attr->getLocation(), diag::attr_only_on_static_properties,
+               attr->getAttrName());
+    } else if (!VarD->hasStorageOrWrapsStorage()) {
+      diagnose(attr->getLocation(), diag::attr_not_on_computed_properties,
+               attr);
+    }
+  }
 }
 
 void AttributeChecker::visitSectionAttr(SectionAttr *attr) {
@@ -2100,9 +2108,20 @@ void AttributeChecker::visitSectionAttr(SectionAttr *attr) {
   if (attr->Name.empty())
     diagnose(attr->getLocation(), diag::section_empty_name);
 
-  if (D->getDeclContext()->isGenericContext())
+  if (D->getDeclContext()->isLocalContext())
+    ; // Already diagnosed in Parse, don't diagnose again
+  else if (D->getDeclContext()->isGenericContext())
     diagnose(attr->getLocation(), diag::attr_only_at_non_generic_scope,
              attr->getAttrName());
+  else if (auto *VarD = dyn_cast<VarDecl>(D)) {
+    if (!VarD->isStatic() && !D->getDeclContext()->isModuleScopeContext()) {
+      diagnose(attr->getLocation(), diag::attr_only_on_static_properties,
+               attr->getAttrName());
+    } else if (!VarD->hasStorageOrWrapsStorage()) {
+      diagnose(attr->getLocation(), diag::attr_not_on_computed_properties,
+               attr);
+    }
+  }
 }
 
 void AttributeChecker::visitUnsafeNoObjCTaggedPointerAttr(

test/IRGen/section_errors.swift

@@ -9,7 +9,9 @@ struct MyStruct {
 }
 
 struct MyStruct2 {
-	@_section("__TEXT,__mysection") var member0: Int = 1
+	@_section("__TEXT,__mysection") var member0: Int = 1 // expected-error {{properties with attribute '_section' must be static}}
+
+	@_section("__TEXT,__mysection") static var member0: Int { return 1 } // expected-error {{'@_section' must not be used on computed properties}}
 }
 
 struct MyStruct3<T> {