From fd1eade4ca02b125b1a2ecea564f32af6a683248 Mon Sep 17 00:00:00 2001
From: LemonBoy <thatlemon@gmail.com>
Date: Wed, 26 Feb 2020 23:17:44 +0100
Subject: ir: Allow empty inferred error sets

Closes #4564
---
 src/analyze.cpp | 47 +++++++++++++++++++++++++----------------------
 1 file changed, 25 insertions(+), 22 deletions(-)

(limited to 'src/analyze.cpp')

diff --git a/src/analyze.cpp b/src/analyze.cpp
index 41ae69f803..9b776da930 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -4771,38 +4771,41 @@ static void analyze_fn_ir(CodeGen *g, ZigFn *fn, AstNode *return_type_node) {
         if (return_err_set_type->data.error_set.infer_fn != nullptr &&
             return_err_set_type->data.error_set.incomplete)
         {
-            ZigType *inferred_err_set_type;
+            // The inferred error set type is null if the function doesn't
+            // return any error
+            ZigType *inferred_err_set_type = nullptr;
+
             if (fn->src_implicit_return_type->id == ZigTypeIdErrorSet) {
                 inferred_err_set_type = fn->src_implicit_return_type;
             } else if (fn->src_implicit_return_type->id == ZigTypeIdErrorUnion) {
                 inferred_err_set_type = fn->src_implicit_return_type->data.error_union.err_set_type;
-            } else {
-                add_node_error(g, return_type_node,
-                        buf_sprintf("function with inferred error set must return at least one possible error"));
-                fn->anal_state = FnAnalStateInvalid;
-                return;
             }
 
-            if (inferred_err_set_type->data.error_set.infer_fn != nullptr &&
-                inferred_err_set_type->data.error_set.incomplete)
-            {
-                if (!resolve_inferred_error_set(g, inferred_err_set_type, return_type_node)) {
-                    fn->anal_state = FnAnalStateInvalid;
-                    return;
+            if (inferred_err_set_type != nullptr) {
+                if (inferred_err_set_type->data.error_set.infer_fn != nullptr &&
+                    inferred_err_set_type->data.error_set.incomplete)
+                {
+                    if (!resolve_inferred_error_set(g, inferred_err_set_type, return_type_node)) {
+                        fn->anal_state = FnAnalStateInvalid;
+                        return;
+                    }
                 }
-            }
 
-            return_err_set_type->data.error_set.incomplete = false;
-            if (type_is_global_error_set(inferred_err_set_type)) {
-                return_err_set_type->data.error_set.err_count = UINT32_MAX;
-            } else {
-                return_err_set_type->data.error_set.err_count = inferred_err_set_type->data.error_set.err_count;
-                if (inferred_err_set_type->data.error_set.err_count > 0) {
-                    return_err_set_type->data.error_set.errors = heap::c_allocator.allocate<ErrorTableEntry *>(inferred_err_set_type->data.error_set.err_count);
-                    for (uint32_t i = 0; i < inferred_err_set_type->data.error_set.err_count; i += 1) {
-                        return_err_set_type->data.error_set.errors[i] = inferred_err_set_type->data.error_set.errors[i];
+                return_err_set_type->data.error_set.incomplete = false;
+                if (type_is_global_error_set(inferred_err_set_type)) {
+                    return_err_set_type->data.error_set.err_count = UINT32_MAX;
+                } else {
+                    return_err_set_type->data.error_set.err_count = inferred_err_set_type->data.error_set.err_count;
+                    if (inferred_err_set_type->data.error_set.err_count > 0) {
+                        return_err_set_type->data.error_set.errors = heap::c_allocator.allocate<ErrorTableEntry *>(inferred_err_set_type->data.error_set.err_count);
+                        for (uint32_t i = 0; i < inferred_err_set_type->data.error_set.err_count; i += 1) {
+                            return_err_set_type->data.error_set.errors[i] = inferred_err_set_type->data.error_set.errors[i];
+                        }
                     }
                 }
+            } else {
+                return_err_set_type->data.error_set.incomplete = false;
+                return_err_set_type->data.error_set.err_count = 0;
             }
         }
     }
-- 
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