An enum member after a string member needs an initializer

tslang/lib/TypeScript/MLIRGenInterfaces.cpp

@@ -42,6 +42,8 @@ namespace mlirgen
         auto activeBits = 32;
         mlir::IntegerType::SignednessSemantics currentEnumValueSigedness = mlir::IntegerType::SignednessSemantics::Signless;
         llvm::APInt currentEnumValue(32, 0);
+        // a member after a string member has no value to count on from
+        auto previousIsString = false;
         for (auto enumMember : enumDeclarationAST->members)
         {
             auto location = loc(enumMember);
@@ -104,6 +106,12 @@ namespace mlirgen
             }
             else
             {
+                if (previousIsString)
+                {
+                    emitError(loc(enumMember)) << "Enum member '" << memberNamePtr << "' must have initializer";
+                    return mlir::failure();
+                }
+
                 if (appending && currentEnumValue == 0 && stage == Stages::Discovering && !enumValues.contains(memberNamePtr))
                 {
                     emitError(loc(enumMember))
@@ -126,6 +134,7 @@ namespace mlirgen
             LLVM_DEBUG(llvm::dbgs() << "\n!! enum: " << namePtr << " value attr: " << enumValueAttr << "\n");
 
             enumValues[memberNamePtr] = enumValueAttr;
+            previousIsString = isa<mlir::StringAttr>(enumValueAttr);
 
             // update enum to support req. access
             SmallVector<mlir::NamedAttribute> namedEnumValues;

tslang/test/tester/CMakeLists.txt

@@ -2947,6 +2947,16 @@ set_tests_properties(test-compile-diagnostic-location-implicit-constructor
                      PROPERTIES PASS_REGULAR_EXPRESSION "implicit_constructor\\.ts:9:1: error: Class constructor is not accessable"
                                 FAIL_REGULAR_EXPRESSION "Stack dump|Assertion failed|implicit_constructor\\.ts:1:")
 
+# An enum member after a string member needs an initializer: it took the count of the members
+# before it.
+add_test(NAME test-compile-diagnostic-location-enum-member-initializer
+         COMMAND $<TARGET_FILE:tslang> --emit=obj --no-default-lib -mm=none
+                 "${PROJECT_SOURCE_DIR}/test/tester/diagnostic-location/enum_member_initializer.ts"
+                 -o "${CMAKE_CURRENT_BINARY_DIR}/diagnostic-location-enum-member-initializer.obj")
+set_tests_properties(test-compile-diagnostic-location-enum-member-initializer
+                     PROPERTIES PASS_REGULAR_EXPRESSION "enum_member_initializer\\.ts:7:5: error: Enum member 'B' must have initializer"
+                                FAIL_REGULAR_EXPRESSION "Stack dump|Assertion failed|enum_member_initializer\\.ts:5:")
+
 # An error in the code the compiler makes for a statement (a for...of's or for...in's loop) is
 # reported at the statement, and one in a `using`'s dispose call at the declaration - not at 1:1,
 # as a node the compiler makes has no position of its own.

tslang/test/tester/diagnostic-location/enum_member_initializer.ts

@@ -0,0 +1,12 @@
+// A member after a string member, with no initializer, had no value to count on from: it
+// quietly took the count of the members before.
+
+enum E {
+    N,
+    A = "x",
+    B,
+}
+
+function main() {
+    print(E.B);
+}