Mark Result and MaybeResult [[nodiscard]] (#7083)

Since these types may be carrying errors that need to be handled or
propagated, it is always an error not to use them in some way. Adding
the [[nodiscard]] attribute caused the compiler to find a few instances
where we were incorrectly ignoring results. Fix these places.

2 files changed, 5 insertions, 5 deletions

diff --git a/src/parser/parsers.h b/src/parser/parsers.h
index 4121788d7..2d3321dcd 100644
--- a/src/parser/parsers.h
+++ b/src/parser/parsers.h
@@ -1099,7 +1099,7 @@ block(Ctx& ctx, const std::vector<Annotation>& annotations, bool folded) {
   auto type = blocktype(ctx);
   CHECK_ERR(type);
 
-  ctx.makeBlock(pos, annotations, label, *type);
+  CHECK_ERR(ctx.makeBlock(pos, annotations, label, *type));
 
   CHECK_ERR(instrs(ctx));
 
@@ -1162,7 +1162,7 @@ ifelse(Ctx& ctx, const std::vector<Annotation>& annotations, bool folded) {
       return ctx.in.err("else label does not match if label");
     }
 
-    ctx.visitElse();
+    CHECK_ERR(ctx.visitElse());
 
     CHECK_ERR(instrs(ctx));
 
@@ -1205,7 +1205,7 @@ loop(Ctx& ctx, const std::vector<Annotation>& annotations, bool folded) {
   auto type = blocktype(ctx);
   CHECK_ERR(type);
 
-  ctx.makeLoop(pos, annotations, label, *type);
+  CHECK_ERR(ctx.makeLoop(pos, annotations, label, *type));
 
   CHECK_ERR(instrs(ctx));
 
diff --git a/src/support/result.h b/src/support/result.h
index ab71d3a53..7cd360d53 100644
--- a/src/support/result.h
+++ b/src/support/result.h
@@ -40,7 +40,7 @@ struct Err {
   }
 
 // Represent a result of type T or an error message.
-template<typename T = Ok> struct Result {
+template<typename T = Ok> struct [[nodiscard]] Result {
   std::variant<T, Err> val;
 
   Result(Result<T>& other) = default;
@@ -56,7 +56,7 @@ template<typename T = Ok> struct Result {
 };
 
 // Represent an optional result of type T or an error message.
-template<typename T = Ok> struct MaybeResult {
+template<typename T = Ok> struct [[nodiscard]] MaybeResult {
   std::variant<T, None, Err> val;
 
   MaybeResult() : val(None{}) {}