Parser: improve handling in nodeIsNoreturn to avoid false positives

src/aro/Parser.zig

@@ -4603,24 +4603,31 @@ fn nodeIsNoreturn(p: *Parser, node: NodeIndex) NoreturnKind {
         },
         .compound_stmt_two => {
             const data = p.nodes.items(.data)[@intFromEnum(node)];
-            if (data.bin.rhs != .none) return p.nodeIsNoreturn(data.bin.rhs);
-            if (data.bin.lhs != .none) return p.nodeIsNoreturn(data.bin.lhs);
+            const lhs_type = if (data.bin.lhs != .none) p.nodeIsNoreturn(data.bin.lhs) else .no;
+            const rhs_type = if (data.bin.rhs != .none) p.nodeIsNoreturn(data.bin.rhs) else .no;
+            if (lhs_type == .complex or rhs_type == .complex) return .complex;
+            if (lhs_type == .yes or rhs_type == .yes) return .yes;
             return .no;
         },
         .compound_stmt => {
             const data = p.nodes.items(.data)[@intFromEnum(node)];
-            return p.nodeIsNoreturn(p.data.items[data.range.end - 1]);
+            var it = data.range.start;
+            while (it != data.range.end) : (it += 1) {
+                const kind = p.nodeIsNoreturn(p.data.items[it]);
+                if (kind != .no) return kind;
+            }
+            return .no;
         },
         .labeled_stmt => {
             const data = p.nodes.items(.data)[@intFromEnum(node)];
             return p.nodeIsNoreturn(data.decl.node);
         },
-        .switch_stmt => {
+        .default_stmt => {
             const data = p.nodes.items(.data)[@intFromEnum(node)];
-            if (data.bin.rhs == .none) return .complex;
-            if (p.nodeIsNoreturn(data.bin.rhs) == .yes) return .yes;
-            return .complex;
+            if (data.un == .none) return .no;
+            return p.nodeIsNoreturn(data.un);
         },
+        .while_stmt, .do_while_stmt, .for_decl_stmt, .forever_stmt, .for_stmt, .switch_stmt => return .complex,
         else => return .no,
     }
 }

test/cases/return.c

@@ -120,7 +120,6 @@ void call_return_signed(void) {
     "return.c:32:5: error: non-void function 'bar' should return a value [-Wreturn-type]" \
     "return.c:35:12: error: void function 'baz' should not return a value [-Wreturn-type]" \
     "return.c:38:17: error: function cannot return a function" \
-    "return.c:74:5: warning: unreachable code [-Wunreachable-code]" \
     "return.c:96:12: error: returning 'double' from a function with incompatible result type 'void *'" \
     "warning: returning 'unsigned int *' from a function with incompatible result type 'int *' converts between pointers to integer types with different sign [-Wpointer-sign]" \
 

test/cases/unreachable code.c

@@ -0,0 +1,38 @@
+int test(int a){
+	switch(a) {
+		default: break;
+	}
+	return 1;
+}
+int test1(int a){
+	switch(a) {
+		break;
+		a=1;
+	}
+	return 1;
+}
+int test2(int a){
+	switch(a) {
+		return 1;
+		a=1;
+	}
+	return 1;
+}
+int compound_stmt(int a){
+	{
+		a=1;
+		return 1;
+		a=2;
+	}
+}
+int if_then_else(int a){
+	if(a)
+		return 1;
+	else
+		return 2;
+	return 3;
+}
+#define EXPECTED_ERRORS "unreachable code.c:10:3: warning: unreachable code [-Wunreachable-code]" \
+	"unreachable code.c:17:3: warning: unreachable code [-Wunreachable-code]" \
+	"unreachable code.c:25:3: warning: unreachable code [-Wunreachable-code]" \
+	"unreachable code.c:33:2: warning: unreachable code [-Wunreachable-code]"