Fix assertion failure on unused reference to _ (#2091)

Fix compiler assertion failure on unused reference to `_`
ponylang · Jul 26, 2017 · 456b458 · 456b458
1 parent 6b066b0
commit 456b458
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Showing 3 changed files with 19 additions and 2 deletions.
diff --git a/src/libponyc/codegen/codegen.h b/src/libponyc/codegen/codegen.h
@@ -59,7 +59,7 @@ LLVMValueRef LLVMLifetimeEnd(LLVMModuleRef module);
 
 #define GEN_NOVALUE ((LLVMValueRef)1)
 
-#define GEN_NOTNEEDED (LLVMConstInt(c->ibool, 0, false))
+#define GEN_NOTNEEDED ((LLVMValueRef)2)
 
 typedef struct genned_string_t genned_string_t;
 DECLARE_HASHMAP(genned_strings, genned_strings_t, genned_string_t);

diff --git a/src/libponyc/codegen/genexpr.c b/src/libponyc/codegen/genexpr.c
@@ -57,7 +57,7 @@ LLVMValueRef gen_expr(compile_t* c, ast_t* ast)
     case TK_DONTCARE:
     case TK_DONTCAREREF:
     case TK_MATCH_DONTCARE:
-      ret = GEN_NOVALUE;
+      ret = GEN_NOTNEEDED;
       break;
 
     case TK_IF:
@@ -257,6 +257,8 @@ LLVMValueRef gen_assign_cast(compile_t* c, LLVMTypeRef l_type,
   if(r_value <= GEN_NOVALUE)
     return r_value;
 
+  pony_assert(r_value != GEN_NOTNEEDED);
+
   LLVMTypeRef r_type = LLVMTypeOf(r_value);
 
   if(r_type == l_type)

diff --git a/test/libponyc/badpony.cc b/test/libponyc/badpony.cc
@@ -803,3 +803,18 @@ TEST_F(BadPonyTest, AsNestedUninferredNumericLiteral)
 
   TEST_ERRORS_1(src, "Cannot cast uninferred literal");
 }
+
+TEST_F(BadPonyTest, DontCareUnusedBranchValue)
+{
+  // From issue #2073
+  const char* src =
+    "actor Main\n"
+    "  new create(env: Env) =>\n"
+    "    if false then\n"
+    "      None\n"
+    "    else\n"
+    "      _\n"
+    "    end";
+
+  TEST_COMPILE(src);
+}