Simplify API, returning StatusOr instead of status vector.

e2e_tests/invalid_constraints.expected.output

@@ -1,63 +1,63 @@
-In table invalid_constraints.forgot_quotes:
+P4Info to constraint info translation failed with the following errors:
+- In table invalid_constraints.forgot_quotes:
 Syntax error: @entry_restriction must be enclosed in '("' and '")'
 
-In table invalid_constraints.forgot_quotes_with_srcloc:
+- In table invalid_constraints.forgot_quotes_with_srcloc:
 Syntax error: @entry_restriction must be enclosed in '("' and '")'
 
-In @entry_restriction of table invalid_constraints.empty_restriction; at offset line 1, column 1:
+- In @entry_restriction of table invalid_constraints.empty_restriction; at offset line 1, column 1:
 Parse error: unexpected token: <END_OF_INPUT>. Expected true, false, <BINARY>, <OCTARY>, <DECIMAL>, <HEXADEC>, <ID>, !, -, or (.
 
-e2e_tests/invalid_constraints.p4:21:3:
+- e2e_tests/invalid_constraints.p4:21:3:
    |   @entry_restriction("
 21 |   ")
    |   ^
 Parse error: unexpected token: <END_OF_INPUT>. Expected true, false, <BINARY>, <OCTARY>, <DECIMAL>, <HEXADEC>, <ID>, !, -, or (.
 
-e2e_tests/invalid_constraints.p4:27:5-15:
+- e2e_tests/invalid_constraints.p4:27:5-15:
    |   @entry_restriction("
 27 |     foo.bar.baz == 2
    |     ^^^^^^^^^^^
 Type error: unknown key foo.bar.baz
 
-In @entry_restriction of table invalid_constraints.unknown_key_no_srcloc; at offset line 1, columns 1 to 11:
+- In @entry_restriction of table invalid_constraints.unknown_key_no_srcloc; at offset line 1, columns 1 to 11:
 Type error: unknown key foo.bar.baz
 
-e2e_tests/invalid_constraints.p4:38:21-22:
+- e2e_tests/invalid_constraints.p4:38:21-22:
    |   @entry_restriction("
 38 |     foo.bar.baz == 0b2
    |                     ^^
 Parse error: unexpected token: <ID>. Expected <END_OF_INPUT>, ), ::, &&, ;, ||, ->, ==, !=, >, >=, <, or <=.
 
-In @entry_restriction of table invalid_constraints.bad_binary_numeral_no_srcloc; at offset line 1, columns 17 to 18:
+- In @entry_restriction of table invalid_constraints.bad_binary_numeral_no_srcloc; at offset line 1, columns 17 to 18:
 Parse error: unexpected token: <ID>. Expected <END_OF_INPUT>, ), ::, &&, ;, ||, ->, ==, !=, >, >=, <, or <=.
 
-e2e_tests/invalid_constraints.p4:52:11-14:
+- e2e_tests/invalid_constraints.p4:52:11-14:
    |     /**************************************************************************/
 52 |     error here
    |           ^^^^
 Parse error: unexpected token: <ID>. Expected <END_OF_INPUT>, ), ::, &&, ;, ||, ->, ==, !=, >, >=, <, or <=.
 
-e2e_tests/invalid_constraints.p4:60:5-15:
+- e2e_tests/invalid_constraints.p4:60:5-15:
    |   @entry_restriction("
 60 |     ternary_key::prefix_length
    |     ^^^^^^^^^^^
 Type error: expression of type ternary<32> has no field 'prefix_length'
 
-e2e_tests/invalid_constraints.p4:70:5-10:
+- e2e_tests/invalid_constraints.p4:70:5-10:
    |   @entry_restriction("
 70 |     0x0F0F :: value
    |     ^^^^^^
 Type error: expression of type int has no field 'value'
 
-e2e_tests/invalid_constraints.p4:77:42-46:
+- e2e_tests/invalid_constraints.p4:77:42-46:
    |   @entry_restriction("
 77 |     -0x0F0F == -0o01234567 -> !false && -false
    |                                          ^^^^^
 Type error: expected type int, got bool
 
-e2e_tests/invalid_constraints.p4:84:33:
+- e2e_tests/invalid_constraints.p4:84:33:
    |   @entry_restriction("
 84 |     !false -> -8 == -0b1000 || !1
    |                                 ^
 Type error: expected type bool, got int
-

p4_constraints/backend/constraint_info.cc

@@ -21,6 +21,7 @@
 #include "absl/container/flat_hash_map.h"
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
+#include "absl/strings/str_join.h"
 #include "absl/strings/string_view.h"
 #include "absl/strings/strip.h"
 #include "absl/types/variant.h"
@@ -160,7 +161,7 @@ absl::StatusOr<TableInfo> ParseTableInfo(const Table& table) {
 
 }  // namespace
 
-absl::variant<ConstraintInfo, std::vector<absl::Status>> P4ToConstraintInfo(
+absl::StatusOr<ConstraintInfo> P4ToConstraintInfo(
     const p4::config::v1::P4Info& p4info) {
   // Allocate output.
   absl::flat_hash_map<uint32_t, TableInfo> info;
@@ -176,8 +177,14 @@ absl::variant<ConstraintInfo, std::vector<absl::Status>> P4ToConstraintInfo(
                        << "duplicate table: " << table.DebugString());
     }
   }
-  if (!errors.empty()) return errors;
-  return info;
+  if (errors.empty()) return info;
+  return gutils::InvalidArgumentErrorBuilder(GUTILS_LOC)
+         << "P4Info to constraint info translation failed with the following "
+            "errors:\n- "
+         << absl::StrJoin(errors, "\n- ",
+                          [](std::string* out, const absl::Status& status) {
+                            absl::StrAppend(out, status.message(), "\n");
+                          });
 }
 
 }  // namespace p4_constraints

p4_constraints/backend/constraint_info.h

@@ -29,6 +29,7 @@
 
 #include "absl/container/flat_hash_map.h"
 #include "absl/status/status.h"
+#include "absl/status/statusor.h"
 #include "absl/types/variant.h"
 #include "p4/config/v1/p4info.pb.h"
 #include "p4_constraints/ast.pb.h"
@@ -65,8 +66,8 @@ using ConstraintInfo = absl::flat_hash_map<uint32_t, TableInfo>;
 //
 // Parses all tables and their constraint annotations into an in-memory
 // representation suitable for constraint checking. Returns parsed
-// representation, or a nonempty list of error statuses if parsing fails.
-absl::variant<ConstraintInfo, std::vector<absl::Status>> P4ToConstraintInfo(
+// representation, or an error statuses if parsing fails.
+absl::StatusOr<ConstraintInfo> P4ToConstraintInfo(
     const p4::config::v1::P4Info& p4info);
 
 }  // namespace p4_constraints

p4_constraints/cli/p4check.cc

@@ -94,16 +94,11 @@ int main(int argc, char** argv) {
   }
 
   // Parse constraints and report potential errors.
-  absl::variant<ConstraintInfo, std::vector<absl::Status>> info_or_errors =
-      P4ToConstraintInfo(p4info);
-  if (absl::holds_alternative<std::vector<absl::Status>>(info_or_errors)) {
-    const auto& errors = absl::get<std::vector<absl::Status>>(info_or_errors);
-    for (const absl::Status& error : errors) {
-      std::cerr << error.message() << "\n\n";
-    }
+  absl::StatusOr<ConstraintInfo> constraint_info = P4ToConstraintInfo(p4info);
+  if (!constraint_info.ok()) {
+    std::cerr << constraint_info.status().message();
     return 1;
   }
-  const auto& constraint_info = absl::get<ConstraintInfo>(info_or_errors);
 
   // Check table entries, if any where given.
   for (const char* entry_filename :
@@ -133,7 +128,7 @@ int main(int argc, char** argv) {
     entry.set_table_id(CoerceToTableId(entry.table_id()));
 
     // Check entry.
-    absl::StatusOr<bool> result = EntryMeetsConstraint(entry, constraint_info);
+    absl::StatusOr<bool> result = EntryMeetsConstraint(entry, *constraint_info);
     if (!result.ok()) {
       std::cout << "Error: " << result.status() << "\n\n";
       continue;