Add protection from calling typeStr with an invalid type

src/aro/Parser.zig

@@ -432,6 +432,11 @@ pub fn removeNull(p: *Parser, str: Value) !Value {
 }
 
 pub fn typeStr(p: *Parser, ty: Type) ![]const u8 {
+    if (@import("builtin").mode != .Debug) {
+        if (ty.is(.invalid)) {
+            return "Tried to render invalid type - this is an aro bug.";
+        }
+    }
     if (Type.Builder.fromType(ty).str(p.comp.langopts)) |str| return str;
     const strings_top = p.strings.items.len;
     defer p.strings.items.len = strings_top;
@@ -446,6 +451,11 @@ pub fn typePairStr(p: *Parser, a: Type, b: Type) ![]const u8 {
 }
 
 pub fn typePairStrExtra(p: *Parser, a: Type, msg: []const u8, b: Type) ![]const u8 {
+    if (@import("builtin").mode != .Debug) {
+        if (a.is(.invalid) or b.is(.invalid)) {
+            return "Tried to render invalid type - this is an aro bug.";
+        }
+    }
     const strings_top = p.strings.items.len;
     defer p.strings.items.len = strings_top;
 
@@ -635,7 +645,6 @@ fn diagnoseIncompleteDefinitions(p: *Parser) !void {
     const tys = node_slices.items(.ty);
     const data = node_slices.items(.data);
 
-    const err_start = p.comp.diagnostics.list.items.len;
     for (p.decl_buf.items) |decl_node| {
         const idx = @intFromEnum(decl_node);
         switch (tags[idx]) {
@@ -656,8 +665,6 @@ fn diagnoseIncompleteDefinitions(p: *Parser) !void {
         try p.errStr(.tentative_definition_incomplete, tentative_def_tok, type_str);
         try p.errStr(.forward_declaration_here, data[idx].decl_ref, type_str);
     }
-    const errors_added = p.comp.diagnostics.list.items.len - err_start;
-    assert(errors_added == 2 * p.tentative_defs.count()); // Each tentative def should add an error + note
 }
 
 /// root : (decl | assembly ';' | staticAssert)*

src/aro/Type.zig

@@ -1056,7 +1056,7 @@ pub fn bitSizeof(ty: Type, comp: *const Compilation) ?u64 {
 }
 
 pub fn alignable(ty: Type) bool {
-    return ty.isArray() or !ty.hasIncompleteSize() or ty.is(.void);
+    return (ty.isArray() or !ty.hasIncompleteSize() or ty.is(.void)) and !ty.is(.invalid);
 }
 
 /// Get the alignment of a type

test/cases/incomplete types.c

@@ -43,6 +43,12 @@ void incomplete_enum_float(void) {
 
 void incomplete_unspecified_variable_len_array(struct S b[1][*]);
 
+void f1(struct Foo *a) { } /* should produce `warning: declaration of 'struct Foo' will not be visible outside of this function [-Wvisibility]` instead of tentative definition error */
+
+struct Foo f;
+
+#define TESTS_SKIPPED 1
+
 #define EXPECTED_ERRORS "incomplete types.c:4:5: error: dereferencing pointer to incomplete type 'struct S'" \
     "incomplete types.c:5:11: error: dereferencing pointer to incomplete type 'struct S'" \
     "incomplete types.c:8:5: error: dereferencing pointer to incomplete type 'union U'" \
@@ -56,3 +62,8 @@ void incomplete_unspecified_variable_len_array(struct S b[1][*]);
     "incomplete types.c:34:13: error: statement requires expression with integer type ('struct node' invalid)" \
     "incomplete types.c:40:12: error: variable has incomplete type 'enum E'" \
     "incomplete types.c:44:58: error: array has incomplete element type 'struct S [*]'" \
+    "incomplete types.c:48:12: error: tentative definition has type 'struct Foo' that is never completed" \
+    "incomplete types.c:46:16: note: forward declaration of 'struct Foo'" \
+    "incomplete types.c:48:12: error: tentative definition has type 'struct Foo' that is never completed" \
+    "incomplete types.c:48:8: note: forward declaration of 'struct Foo'" \
+