Add some basic assertion handling control options

Author: tbkka

include/swift/Basic/Assertions.h

@@ -44,7 +44,7 @@
   } while (0)
 
 // Function that reports the actual failure when it occurs.
-[[noreturn]] void ASSERT_failure(const char *expr, const char *file, int line, const char *func);
+void ASSERT_failure(const char *expr, const char *file, int line, const char *func);
 
 // ================================ Conditional Asserts ================================
 
@@ -171,4 +171,11 @@ extern int CONDITIONAL_ASSERT_Global_enable_flag;
 #define SWIFT_ASSERT_ONLY_DECL DEBUG_ASSERT_DECL
 #define SWIFT_ASSERT_ONLY DEBUG_ASSERT_EXPR
 
+// ================================ Utility and Helper Functions ================================
+
+// Utility function to print out help information for
+// various command-line options that affect the assertion
+// behavior.
+void ASSERT_help();
+
 #endif // SWIFT_BASIC_ASSERTIONS_H

lib/Basic/Assertions.cpp

@@ -14,19 +14,28 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Support/CommandLine.h"
 #include "swift/Basic/Assertions.h"
 #undef NDEBUG
 #include <cassert>
 #include <iostream>
 
+llvm::cl::opt<bool> AssertContinue(
+    "assert-continue", llvm::cl::init(false),
+    llvm::cl::desc("Do not stop on an assertion failure"));
+
+llvm::cl::opt<bool> AssertHelp(
+    "assert-help", llvm::cl::init(false),
+    llvm::cl::desc("Print help for managing assertions"));
+
 int CONDITIONAL_ASSERT_Global_enable_flag =
 #ifdef NDEBUG
   0; // Default to `off` in release builds
 #else
   0; // TODO: Default to `on` in debug builds
 #endif
 
-[[noreturn]] void ASSERT_failure(const char *expr, const char *file, int line, const char *func) {
+void ASSERT_failure(const char *expr, const char *file, int line, const char *func) {
   // Only print the last component of `file`
   const char *f = file;
   for (const char *p = file; *p != '\0'; p++) {
@@ -35,6 +44,14 @@ int CONDITIONAL_ASSERT_Global_enable_flag =
       f = p + 1;
     }
   }
+
+  if (AssertHelp) {
+    ASSERT_help();
+  } else {
+    std::cerr << "Assertion help:  -Xllvm -assert-help" << std::endl;
+  }
+
+
   // Format here matches that used by `assert` on macOS:
   std::cerr
     << "Assertion failed: "
@@ -43,9 +60,30 @@ int CONDITIONAL_ASSERT_Global_enable_flag =
     << "file " << f << ", "
     << "line " << line << "."
     << std::endl;
+
+  if (AssertContinue) {
+    std::cerr << "Continuing after failed assertion (-Xllvm -assert-continue)" << std::endl;
+    return;
+  }
+
   abort();
 }
 
+void ASSERT_help() {
+  static int ASSERT_help_shown = 0;
+  if (ASSERT_help_shown) {
+    return;
+  }
+  ASSERT_help_shown = 1;
+
+  std::cerr << std::endl;
+  std::cerr << "Control assertion behavior with one or more of the following options:" << std::endl;
+  std::cerr << std::endl;
+  std::cerr << " -Xllvm -assert-continue" << std::endl;
+  std::cerr << "     Continue after any failed assertion" << std::endl;
+  std::cerr << std::endl;
+}
+
 // This has to be callable in the same way as the macro version,
 // so we can't put it inside a namespace.
 #undef CONDITIONAL_ASSERT_enabled