Refactor: create QLJS_CONSTEXPR_ASSERT macro

Express intent by creating a documented QLJS_CONSTEXPR_ASSERT macro for
our constexpr asm("") hack.

Author: strager

src/quick-lint-js/assert.h

@@ -74,6 +74,24 @@
 
 #define QLJS_ASSERT_TRAP() QLJS_CRASH_ALLOWING_CORE_DUMP()
 
+// QLJS_CONSTEXPR_ASSERT is like QLJS_ALWAYS_ASSERT, except:
+//
+// * It must only be called in a constexpr function.
+// * It must only be called at compile time (i.e. not a run-time constexpr
+//   function).
+// * It works only with some compilers.
+#if __cpp_constexpr >= 201907L && !defined(_MSC_VER)
+#define QLJS_CONSTEXPR_ASSERT(...) \
+  do {                             \
+    if (__VA_ARGS__) {             \
+    } else {                       \
+      asm("");                     \
+    }                              \
+  } while (false)
+#else
+#define QLJS_CONSTEXPR_ASSERT(...) QLJS_NEVER_ASSERT(__VA_ARGS__)
+#endif
+
 namespace quick_lint_js {
 void report_assertion_failure(const char *qljs_file_name, int qljs_line,
                               const char *qljs_function_name,

src/quick-lint-js/translation-table-generated.h

@@ -9,6 +9,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <iterator>
+#include <quick-lint-js/assert.h>
 #include <quick-lint-js/consteval.h>
 #include <quick-lint-js/hash-fnv.h>
 #include <quick-lint-js/translation-table.h>
@@ -430,12 +431,9 @@ QLJS_CONSTEVAL std::uint16_t translation_table_const_hash_table_look_up(
     }
   }
 
-  // Helpfully fail compilation if this file is out of date.
-#if __cpp_constexpr >= 201907L && !defined(_MSC_VER)
   // If you see an error with the following line, translation-table-generated.h
   // is out of date. Run tools/update-translator-sources to rebuild this file.
-  asm("");
-#endif
+  QLJS_CONSTEXPR_ASSERT(false);
 
   return 0;
 }

tools/compile-translations.go

@@ -443,6 +443,7 @@ func WriteTranslationTableHeader(table *TranslationTable, path string) error {
 #include <cstddef>
 #include <cstdint>
 #include <iterator>
+#include <quick-lint-js/assert.h>
 #include <quick-lint-js/consteval.h>
 #include <quick-lint-js/hash-fnv.h>
 #include <quick-lint-js/translation-table.h>
@@ -490,12 +491,9 @@ using namespace std::literals::string_view_literals;
     }
   }
 
-  // Helpfully fail compilation if this file is out of date.
-#if __cpp_constexpr >= 201907L && !defined(_MSC_VER)
   // If you see an error with the following line, translation-table-generated.h
   // is out of date. Run tools/update-translator-sources to rebuild this file.
-  asm("");
-#endif
+  QLJS_CONSTEXPR_ASSERT(false);
 
   return 0;
 }