Improve flow analysis of catch clauses

Duplicated catch clauses for the same error are detected as an error
and unreachable catch clauses due to preceding catch clauses are
reported with a warning.

diff --git a/vala/valaflowanalyzer.vala b/vala/valaflowanalyzer.vala
index 06b79f8b6f81d94af46f2697346c733fc246ac17..621ce4b63eaa6cd964c92802cc6006c5e60233d2 100644 (file)
--- a/vala/valaflowanalyzer.vala
+++ b/vala/valaflowanalyzer.vala
@@ -130,8 +130,8 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 
        public override void visit_method (Method m) {
                if (m.is_library_internal_symbol () && !m.used && !m.entry_point
-                    && !m.overrides && (m.base_interface_method == null || m.base_interface_method == m)
-                    && !(m is CreationMethod)) {
+                        && !m.overrides && (m.base_interface_method == null || m.base_interface_method == m)
+                        && !(m is CreationMethod)) {
                        Report.warning (m.source_reference, "method `%s' never used".printf (m.get_full_name ()));
                }
 
@@ -1014,7 +1014,8 @@ public class Vala.FlowAnalyzer : CodeVisitor {
                for (int i = catch_clauses.size - 1; i >= 0; i--) {
                        var catch_clause = catch_clauses[i];
                        if (catch_clause.error_type != null) {
-                               jump_stack.add (new JumpTarget.error_target (new BasicBlock (), catch_clause, catch_clause.error_type.data_type as ErrorDomain, null));
+                               var error_type = catch_clause.error_type as ErrorType;
+                               jump_stack.add (new JumpTarget.error_target (new BasicBlock (), catch_clause, catch_clause.error_type.data_type as ErrorDomain, error_type.error_code));
                        } else {
                                jump_stack.add (new JumpTarget.error_target (new BasicBlock (), catch_clause, null, null));
                        }
@@ -1041,6 +1042,25 @@ public class Vala.FlowAnalyzer : CodeVisitor {
                }
 
                foreach (JumpTarget jump_target in catch_stack) {
+
+                       foreach (JumpTarget prev_target in catch_stack) {
+                               if (prev_target == jump_target)
+                                       break;
+
+                               if (prev_target.error_domain == jump_target.error_domain &&
+                                 prev_target.error_code == jump_target.error_code) {
+                                       Report.error (stmt.source_reference, "double catch clause of same error detected");
+                                       stmt.error = true;
+                                       return;
+                               }
+
+                               if ((prev_target.error_domain == null) ||
+                                 ((prev_target.error_domain != jump_target.error_domain) &&
+                                 (prev_target.error_code == null))) {
+                                       Report.warning (jump_target.catch_clause.source_reference, "unreachable catch clause detected");
+                               }
+                       }
+
                        if (jump_target.basic_block.get_predecessors ().size == 0) {
                                // unreachable
                                Report.warning (jump_target.catch_clause.source_reference, "unreachable catch clause detected");