1 files changed, 74 insertions, 0 deletions
diff --git a/clang/test/C/C23/n3037.c b/clang/test/C/C23/n3037.c
index ce6f4c4..3748375 100644
--- a/clang/test/C/C23/n3037.c
+++ b/clang/test/C/C23/n3037.c
@@ -401,3 +401,77 @@ _Static_assert(0 == _Generic(inner_anon_tagged.untagged, struct { int i; } : 1,
 // unions and structures are both RecordDecl objects, whereas EnumDecl is not).
 enum { E_Untagged1 } nontag_enum; // both-note {{previous definition is here}}
 _Static_assert(0 == _Generic(nontag_enum, enum { E_Untagged1 } : 1, default : 0)); // both-error {{redefinition of enumerator 'E_Untagged1'}}
+
+// Test that enumerations with mixed underlying types are properly handled.
+enum GH150594_E1 : int { GH150594_Val1 };
+enum GH150594_E2 : int { GH150594_Val2 };
+enum GH150594_E3 { GH150594_Val3 };
+enum GH150594_E4 : int { GH150594_Val4 };
+void GH150594(void) {
+  extern enum GH150594_E1 Fn1(void); // both-note {{previous declaration is here}}
+  extern enum GH150594_E2 Fn2(void); // c17-note {{previous declaration is here}}
+  extern enum GH150594_E3 Fn3(void); // both-note {{previous declaration is here}}
+  extern enum GH150594_E4 Fn4(void); // both-note {{previous declaration is here}}
+  enum GH150594_E1 { GH150594_Val1 };
+  enum GH150594_E2 : int { GH150594_Val2 };
+  enum GH150594_E3 : int { GH150594_Val3 };
+  enum GH150594_E4 : short { GH150594_Val4 };
+  extern enum GH150594_E1 Fn1(void); // both-error {{conflicting types for 'Fn1'}}
+  extern enum GH150594_E2 Fn2(void); // c17-error {{conflicting types for 'Fn2'}}
+  extern enum GH150594_E3 Fn3(void); // both-error {{conflicting types for 'Fn3'}}
+  extern enum GH150594_E4 Fn4(void); // both-error {{conflicting types for 'Fn4'}}
+
+  // Show that two declarations in the same scope give expected diagnostics.
+  enum E1 { e1 };       // both-note {{previous declaration is here}}
+  enum E1 : int { e1 }; // both-error {{enumeration previously declared with nonfixed underlying type}}
+
+  enum E2 : int { e2 }; // both-note {{previous declaration is here}}
+  enum E2 { e2 };       // both-error {{enumeration previously declared with fixed underlying type}}
+
+  enum E3 : int { e3 };   // both-note {{previous declaration is here}}
+  enum E3 : short { e3 }; // both-error {{enumeration redeclared with different underlying type 'short' (was 'int')}}
+
+  typedef short foo;
+  enum E4 : foo { e4 };   // c17-note 2 {{previous definition is here}}
+  enum E4 : short { e4 }; // c17-error {{redefinition of 'E4'}} \
+                             c17-error {{redefinition of enumerator 'e4'}}
+
+  enum E5 : foo { e5 }; // both-note {{previous declaration is here}}
+  enum E5 : int { e5 }; // both-error {{enumeration redeclared with different underlying type 'int' (was 'foo' (aka 'short'))}}
+}
+
+// Test that enumerations are compatible with their underlying type, but still
+// diagnose when "same type" is required rather than merely "compatible type".
+enum E1 : int { e1 }; // Fixed underlying type
+enum E2 { e2 };       // Unfixed underlying type, defaults to int or unsigned int
+
+struct GH149965_1 { int h; };
+// This typeof trick is used to get the underlying type of the enumeration in a
+// platform agnostic way.
+struct GH149965_2 { __typeof__(+(enum E2){}) h; };
+void gh149965(void) {
+  extern struct GH149965_1 x1; // c17-note {{previous declaration is here}}
+  extern struct GH149965_2 x2; // c17-note {{previous declaration is here}}
+
+  // Both the structure and the variable declarations are fine because only a
+  // compatible type is required, not the same type, because the structures are
+  // declared in different scopes.
+  struct GH149965_1 { enum E1 h; };
+  struct GH149965_2 { enum E2 h; };
+
+  extern struct GH149965_1 x1; // c17-error {{redeclaration of 'x1'}}
+  extern struct GH149965_2 x2; // c17-error {{redeclaration of 'x2'}}
+
+  // However, in the same scope, the same type is required, not just compatible
+  // types.
+  // FIXME: this should be an error in both C17 and C23 mode.
+  struct GH149965_3 { int h; };     // c17-note {{previous definition is here}}
+  struct GH149965_3 { enum E1 h; }; // c17-error {{redefinition of 'GH149965_3'}}
+
+  // For Clang, the composite type after declaration merging is the enumeration
+  // type rather than an integer type.
+  enum E1 *eptr;
+  [[maybe_unused]] __typeof__(x1.h) *ptr = eptr;
+  enum E2 *eptr2;
+  [[maybe_unused]] __typeof__(x2.h) *ptr2 = eptr2;
+}