pw_assert: Rename assert/check headers

- Rename assert.h to check.h, since it provides PW_CHECK.
- Rename light.h to assert.h, since it provides PW_ASSERT.
- Move short CHECK macros to pw_assert/short.h.
- Have light.h include assert.h and assert.h include check.h for
  backwards compatibility.

Bug: 350
Change-Id: I3ad69d1593a3ca9b8daf63aec2c849f9388aa58c
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/38720
Reviewed-by: Keir Mierle <keir@google.com>
Commit-Queue: Wyatt Hepler <hepler@google.com>

9 files changed, 290 insertions, 270 deletions

diff --git a/pw_assert/BUILD b/pw_assert/BUILD
index 682dfd4c1..58ce60111 100644
--- a/pw_assert/BUILD
+++ b/pw_assert/BUILD
@@ -29,9 +29,11 @@ pw_cc_library(
     name = "facade",
     hdrs = [
         "public/pw_assert/assert.h",
-        "public/pw_assert/internal/assert_impl.h",
+        "public/pw_assert/check.h",
+        "public/pw_assert/internal/check_impl.h",
         "public/pw_assert/light.h",
         "public/pw_assert/options.h",
+        "public/pw_assert/short.h",
     ],
     includes = ["public"],
     deps = [
diff --git a/pw_assert/BUILD.gn b/pw_assert/BUILD.gn
index 084aa00be..5e83da1eb 100644
--- a/pw_assert/BUILD.gn
+++ b/pw_assert/BUILD.gn
@@ -31,15 +31,21 @@ pw_facade("pw_assert") {
   backend = pw_assert_BACKEND
   public_configs = [ ":default_config" ]
   public = [
-    "public/pw_assert/assert.h",
-    "public/pw_assert/internal/assert_impl.h",
+    "public/pw_assert/check.h",
+    "public/pw_assert/internal/check_impl.h",
+    "public/pw_assert/short.h",
   ]
   public_deps = [
     dir_pw_preprocessor,
 
-    # Also expose light.h to all users of pw_assert.
+    # Also expose assert.h to all users of pw_assert.
     ":light",
   ]
+
+  # TODO(pwbug/350): Allow assert.h to include check.h for backwards
+  #     compatibility. Remove this when projects have migrated.
+  allow_circular_includes_from = [ ":light" ]
+  deps = [ ":light" ]
 }
 
 # Provide a way include "pw_assert/light.h" without depending on the full
@@ -51,6 +57,7 @@ pw_facade("pw_assert") {
 pw_source_set("light") {
   public_configs = [ ":default_config" ]
   public = [
+    "public/pw_assert/assert.h",
     "public/pw_assert/light.h",
 
     # Needed for PW_ASSERT_ENABLE_DEBUG. Note that depending on :pw_assert to
@@ -85,7 +92,7 @@ pw_test("assert_facade_test") {
   sources = [
     "assert_facade_test.cc",
     "fake_backend.cc",
-    "public/pw_assert/internal/assert_impl.h",
+    "public/pw_assert/internal/check_impl.h",
     "pw_assert_test/fake_backend.h",
   ]
   deps = [
diff --git a/pw_assert/assert_facade_test.cc b/pw_assert/assert_facade_test.cc
index 376bdf533..088f72596 100644
--- a/pw_assert/assert_facade_test.cc
+++ b/pw_assert/assert_facade_test.cc
@@ -22,8 +22,7 @@
 // assert backend from triggering.
 //
 // clang-format off
-#define PW_ASSERT_USE_SHORT_NAMES 1
-#include "pw_assert/internal/assert_impl.h"
+#include "pw_assert/internal/check_impl.h"
 // clang-format on
 
 #include "gtest/gtest.h"
@@ -453,26 +452,6 @@ TEST(AssertPass, DCheckDisabledBinaryOpTwoSideEffectingCalls_2) {
 }
 #endif  // PW_ASSERT_ENABLE_DEBUG
 
-// Note: This requires enabling PW_ASSERT_USE_SHORT_NAMES 1 above.
-TEST(Check, ShortNamesWork) {
-  // Crash
-  CRASH("msg");
-  CRASH("msg: %d", 5);
-
-  // Check
-  CHECK(true);
-  CHECK(true, "msg");
-  CHECK(true, "msg: %d", 5);
-  CHECK(false);
-  CHECK(false, "msg");
-  CHECK(false, "msg: %d", 5);
-
-  // Check with binary comparison
-  CHECK_INT_LE(1, 2);
-  CHECK_INT_LE(1, 2, "msg");
-  CHECK_INT_LE(1, 2, "msg: %d", 5);
-}
-
 // Verify PW_CHECK_OK, including message handling.
 TEST_F(AssertFail, StatusNotOK) {
   pw::Status status = pw::Status::Unknown();
diff --git a/pw_assert/docs.rst b/pw_assert/docs.rst
index aec33436a..73f0659c6 100644
--- a/pw_assert/docs.rst
+++ b/pw_assert/docs.rst
@@ -25,11 +25,11 @@ The ``pw_assert`` API provides three classes of macros:
   a message.
 - **PW_CHECK_<type>_<cmp>(a, b[, fmt, ...])** - Assert that the expression ``a
   <cmp> b`` is true, optionally with a message.
-- **PW_ASSERT(condition)** - Header- and constexpr- assert.
+- **PW_ASSERT(condition)** - Header- and constexpr-safe assert.
 
 .. tip::
 
-  All of the assert macros optionally support a message with additional
+  All of the ``CHECK`` macros optionally support a message with additional
   arguments, to assist in debugging when an assert triggers:
 
   .. code-block:: cpp
@@ -42,7 +42,7 @@ Example
 
 .. code-block:: cpp
 
-  #include "pw_assert/assert.h"
+  #include "pw_assert/check.h"
 
   int main() {
     bool sensor_running = StartSensor(&msg);
@@ -72,7 +72,7 @@ Example
 
 .. tip::
 
-  Use ``PW_ASSERT`` from ``pw_assert/light.h`` for asserts in headers or
+  Use ``PW_ASSERT`` from ``pw_assert/assert.h`` for asserts in headers or
   asserting in ``constexpr`` contexts.
 
 Structure of assert modules
@@ -102,9 +102,8 @@ See the Backend API section below for more details.
 ----------
 Facade API
 ----------
-
 The below functions describe the assert API functions that applications should
-invoke to assert. These macros found in the ``pw_assert/assert.h`` header.
+invoke to assert. These macros are found in the ``pw_assert/check.h`` header.
 
 .. cpp:function:: PW_CRASH(format, ...)
 
@@ -392,9 +391,9 @@ invoke to assert. These macros found in the ``pw_assert/assert.h`` header.
     code; for example ``status == RESOURCE_EXHAUSTED`` instead of ``status ==
     5``.
 
----------
-Light API
----------
+----------
+Assert API
+----------
 The normal ``PW_CHECK_*`` and ``PW_DCHECK_*`` family of macros are intended to
 provide rich debug information, like the file, line number, value of operands
 in boolean comparisons, and more. However, this comes at a cost: these macros
@@ -411,12 +410,11 @@ There are several issues with the normal ``PW_CHECK_*`` suite of macros:
 4. ``PW_CHECK_*`` can trigger circular dependencies when asserts are used from
    low-level contexts, like in ``<span>``.
 
-**Light asserts** solve all of the above three problems: No risk of ODR
-violations, are constexpr safe, and have a tiny call site footprint; and there
-is no header dependency on the backend preventing circular include issues.
-However, there are **no format messages, no captured line number, no captured
-file, no captured expression, or anything other than a binary indication of
-failure**.
+**PW_ASSERT** solves all of the above problems: No risk of ODR violations, are
+constexpr safe, and have a tiny call site footprint; and there is no header
+dependency on the backend preventing circular include issues.  However, there
+are **no format messages, no captured line number, no captured file, no captured
+expression, or anything other than a binary indication of failure**.
 
 Example
 -------
@@ -425,7 +423,7 @@ Example
 
   // This example demonstrates asserting in a header.
 
-  #include "pw_assert/light.h"
+  #include "pw_assert/assert.h"
 
   class InlinedSubsystem {
    public:
@@ -441,8 +439,8 @@ Example
     }
   };
 
-Light API reference
--------------------
+PW_ASSERT API reference
+-----------------------
 .. cpp:function:: PW_ASSERT(condition)
 
   A header- and constexpr-safe version of ``PW_CHECK()``.
@@ -468,10 +466,11 @@ Light API reference
 
   Use ``PW_CHECK_*()`` whenever possible.
 
-Light API backend
------------------
-The light API ultimately calls the C function ``pw_assert_HandleFailure()``,
-which must be provided by the assert backend.
+PW_ASSERT API backend
+---------------------
+The ``PW_ASSERT`` API ultimately calls the C function
+``pw_assert_HandleFailure()``, which must be provided by the ``pw_assert``
+backend.
 
 -----------
 Backend API
@@ -547,14 +546,14 @@ and that header must define the following macros:
     See :ref:`module-pw_assert_basic` for one way to combine these arguments
     into a meaningful error message.
 
-Additionally, the backend must provide a link-time function for the light
-assert handler. This does not need to appear in the backend header, but instead
-is in a ``.cc`` file.
+Additionally, the backend must provide a link-time function for the
+``PW_ASSERT`` assert handler. This does not need to appear in the backend
+header, but instead is in a ``.cc`` file.
 
 .. cpp:function:: pw_assert_HandleFailure()
 
   Handle a low-level crash. This crash entry happens through
-  ``pw_assert/light.h``. In this crash handler, there is no access to line,
+  ``pw_assert/assert.h``. In this crash handler, there is no access to line,
   file, expression, or other rich assert information. Backends should do
   something reasonable in this case; typically, capturing the stack is useful.
 
diff --git a/pw_assert/public/pw_assert/assert.h b/pw_assert/public/pw_assert/assert.h
index 2a4c999bc..a6756a658 100644
--- a/pw_assert/public/pw_assert/assert.h
+++ b/pw_assert/public/pw_assert/assert.h
@@ -11,104 +11,52 @@
 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 // License for the specific language governing permissions and limitations under
 // the License.
-// =============================================================================
-//
-// This file describes Pigweed's public user-facing assert API.
-//
-// THIS API IS NOT STABLE OR COMPLETE! NEITHER FACADE NOR BACKEND API!
-//
 #pragma once
 
-#include "pw_preprocessor/arguments.h"
+#include "pw_assert/options.h"  // For PW_ASSERT_ENABLE_DEBUG
+#include "pw_preprocessor/util.h"
 
-// The pw_assert public API:
-//
-//   Trigger a crash with a message. Replaces LOG_FATAL() in other systems.
-//   PW_CRASH(msg, ...)
-//
-//   In all below cases, the message argument is optional:
-//   PW_CHECK_INT_LE(x, y) or
-//   PW_CHECK_INT_LE(x, y, "Was booting %s subsystem", subsystem_name)
-//
-//   Asserts the condition, crashes on failure. Equivalent to assert.
-//   PW_CHECK(condition) or
-//   PW_CHECK(condition, msg, ...)
-//
-//   Some common typed checks.
-//   PW_CHECK_OK(status, msg, ...)  Asserts status == PW_STATUS_OK
-//   PW_CHECK_NOTNULL(ptr, msg, ...)  Asserts ptr != NULL
-//
-//   In many cases an assert is a binary comparison. In those cases, using the
-//   special binary assert macros below for <, <=, >, >=, == enables reporting
-//   the values of the operands in addition to the string of the condition.
-//
-//   Binary comparison asserts for 'int' type ("%d" in format strings):
-//   PW_CHECK_INT_LE(a, b, msg, ...)  Asserts a <= b
-//   PW_CHECK_INT_LT(a, b, msg, ...)  Asserts a <  b
-//   PW_CHECK_INT_GE(a, b, msg, ...)  Asserts a >= b
-//   PW_CHECK_INT_GT(a, b, msg, ...)  Asserts a >  b
-//   PW_CHECK_INT_EQ(a, b, msg, ...)  Asserts a == b
-//   PW_CHECK_INT_NE(a, b, msg, ...)  Asserts a != b
-//
-//   Binary comparison asserts for 'unsigned int' type ("%u" in format strings):
-//   PW_CHECK_UINT_LE(a, b, msg, ...)  Asserts a <= b
-//   PW_CHECK_UINT_LT(a, b, msg, ...)  Asserts a <  b
-//   PW_CHECK_UINT_GE(a, b, msg, ...)  Asserts a >= b
-//   PW_CHECK_UINT_GT(a, b, msg, ...)  Asserts a >  b
-//   PW_CHECK_UINT_EQ(a, b, msg, ...)  Asserts a == b
-//   PW_CHECK_UINT_NE(a, b, msg, ...)  Asserts a != b
-//
-//   Binary comparison asserts for 'void*' type ("%p" in format strings):
-//   PW_CHECK_PTR_LE(a, b, msg, ...)  Asserts a <= b
-//   PW_CHECK_PTR_LT(a, b, msg, ...)  Asserts a <  b
-//   PW_CHECK_PTR_GE(a, b, msg, ...)  Asserts a >= b
-//   PW_CHECK_PTR_GT(a, b, msg, ...)  Asserts a >  b
-//   PW_CHECK_PTR_EQ(a, b, msg, ...)  Asserts a == b
-//   PW_CHECK_PTR_NE(a, b, msg, ...)  Asserts a != b
-//
-//   Binary comparison asserts for 'float' type ("%f" in format strings):
-//   PW_CHECK_FLOAT_NEAR(a, b, abs_tolerance, msg, ...)
-//     Asserts (a >= (b - abs_tolerance)) && (a <= (b + abs_tolerance))
-//   PW_CHECK_FLOAT_EXACT_LE(a, b, msg, ...)  Asserts a <= b
-//   PW_CHECK_FLOAT_EXACT_LT(a, b, msg, ...)  Asserts a <  b
-//   PW_CHECK_FLOAT_EXACT_GE(a, b, msg, ...)  Asserts a >= b
-//   PW_CHECK_FLOAT_EXACT_GT(a, b, msg, ...)  Asserts a >  b
-//   PW_CHECK_FLOAT_EXACT_EQ(a, b, msg, ...)  Asserts a == b
-//   PW_CHECK_FLOAT_EXACT_NE(a, b, msg, ...)  Asserts a != b
-//
-//   The above CHECK_*_*() are also available in DCHECK variants, which will
-//   only evaluate their arguments and trigger if the NDEBUG macro is defined.
-//
-//   Note: For float, proper comparator checks which take floating point
-//   precision and ergo error accumulation into account are not provided on
-//   purpose as this comes with some complexity and requires application
-//   specific tolerances in terms of Units of Least Precision (ULP). Instead,
-//   we recommend developers carefully consider how floating point precision and
-//   error impact the data they are bounding and whether CHECKs are appropriate.
-//
-//   Note: PW_CRASH is the equivalent of LOG_FATAL in other systems, where a
-//   device crash is triggered with a message. In Pigweed, logging and
-//   crashing/asserting are separated. There is a LOG_CRITICAL level in the
-//   logging module, but it does not have side effects; for LOG_FATAL, instead
-//   use this macro (PW_CRASH).
-//
-// The public macro definitions are split out into an impl file to facilitate
-// testing the facade logic directly, without going through the facade/backend
-// build facilities.
-#include "pw_assert/internal/assert_impl.h"
+// For backwards compatibility, include check.h from assert.h.
+// TODO(pwbug/350): Remove this include when projects have migrated.
+#include "pw_assert/check.h"
 
-// The pw_assert_backend must provide these macros:
-//
-//   PW_HANDLE_CRASH(msg, ...)
-//   PW_HANDLE_ASSERT_FAILURE(condition, msg, ...)
-//   PW_HANDLE_ASSERT_BINARY_COMPARE_FAILURE(a, op, b, type_fmt, msg, ...)
-//
-//   The low level functionality of triggering a crash, rebooting a device,
-//   collecting information, or hanging out in a while(1) loop, must be
-//   provided by the underlying assert backend as part of the crash or assert
-//   failure handling.
-//
-//   Note that for the assert failures, the handler should assume the assert
-//   has already failed (the facade checks the condition before delegating).
-//
-#include "pw_assert_backend/assert_backend.h"
+PW_EXTERN_C_START
+
+void pw_assert_HandleFailure(void);
+
+PW_EXTERN_C_END
+
+// A header- and constexpr-safe version of PW_CHECK().
+//
+// If the given condition is false, crash the system. Otherwise, do nothing.
+// The condition is guaranteed to be evaluated. This assert implementation is
+// guaranteed to be constexpr-safe.
+//
+// IMPORTANT: Unlike the PW_CHECK_*() suite of macros, this API captures no
+// rich information like line numbers, the file, expression arguments, or the
+// stringified expression. Use these macros only when absolutely necessary --
+// in headers, constexr contexts, or in rare cases where the call site overhead
+// of a full PW_CHECK must be avoided. Use PW_CHECK_*() whenever possible.
+#define PW_ASSERT(condition)     \
+  do {                           \
+    if (!(condition)) {          \
+      pw_assert_HandleFailure(); \
+    }                            \
+  } while (0)
+
+// A header- and constexpr-safe version of PW_DCHECK().
+//
+// Same as PW_ASSERT(), except that if PW_ASSERT_ENABLE_DEBUG == 1, the assert
+// is disabled and condition is not evaluated.
+//
+// IMPORTANT: Unlike the PW_CHECK_*() suite of macros, this API captures no
+// rich information like line numbers, the file, expression arguments, or the
+// stringified expression. Use these macros only when absolutely necessary --
+// in headers, constexr contexts, or in rare cases where the call site overhead
+// of a full PW_CHECK must be avoided. Use PW_DCHECK_*() whenever possible.
+#define PW_DASSERT(condition)                            \
+  do {                                                   \
+    if ((PW_ASSERT_ENABLE_DEBUG == 1) && !(condition)) { \
+      pw_assert_HandleFailure();                         \
+    }                                                    \
+  } while (0)
diff --git a/pw_assert/public/pw_assert/check.h b/pw_assert/public/pw_assert/check.h
new file mode 100644
index 000000000..1cb4eb73e
--- /dev/null
+++ b/pw_assert/public/pw_assert/check.h
@@ -0,0 +1,121 @@
+// Copyright 2020 The Pigweed Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+// =============================================================================
+//
+// This file describes Pigweed's public user-facing assert API.
+//
+// THIS API IS NOT STABLE OR COMPLETE! NEITHER FACADE NOR BACKEND API!
+//
+#pragma once
+
+#include "pw_preprocessor/arguments.h"
+
+// The pw_assert public API:
+//
+//   Trigger a crash with a message. Replaces LOG_FATAL() in other systems.
+//   PW_CRASH(msg, ...)
+//
+//   In all below cases, the message argument is optional:
+//   PW_CHECK_INT_LE(x, y) or
+//   PW_CHECK_INT_LE(x, y, "Was booting %s subsystem", subsystem_name)
+//
+//   Asserts the condition, crashes on failure. Equivalent to assert.
+//   PW_CHECK(condition) or
+//   PW_CHECK(condition, msg, ...)
+//
+//   Some common typed checks.
+//   PW_CHECK_OK(status, msg, ...)  Asserts status == PW_STATUS_OK
+//   PW_CHECK_NOTNULL(ptr, msg, ...)  Asserts ptr != NULL
+//
+//   In many cases an assert is a binary comparison. In those cases, using the
+//   special binary assert macros below for <, <=, >, >=, == enables reporting
+//   the values of the operands in addition to the string of the condition.
+//
+//   Binary comparison asserts for 'int' type ("%d" in format strings):
+//   PW_CHECK_INT_LE(a, b, msg, ...)  Asserts a <= b
+//   PW_CHECK_INT_LT(a, b, msg, ...)  Asserts a <  b
+//   PW_CHECK_INT_GE(a, b, msg, ...)  Asserts a >= b
+//   PW_CHECK_INT_GT(a, b, msg, ...)  Asserts a >  b
+//   PW_CHECK_INT_EQ(a, b, msg, ...)  Asserts a == b
+//   PW_CHECK_INT_NE(a, b, msg, ...)  Asserts a != b
+//
+//   Binary comparison asserts for 'unsigned int' type ("%u" in format strings):
+//   PW_CHECK_UINT_LE(a, b, msg, ...)  Asserts a <= b
+//   PW_CHECK_UINT_LT(a, b, msg, ...)  Asserts a <  b
+//   PW_CHECK_UINT_GE(a, b, msg, ...)  Asserts a >= b
+//   PW_CHECK_UINT_GT(a, b, msg, ...)  Asserts a >  b
+//   PW_CHECK_UINT_EQ(a, b, msg, ...)  Asserts a == b
+//   PW_CHECK_UINT_NE(a, b, msg, ...)  Asserts a != b
+//
+//   Binary comparison asserts for 'void*' type ("%p" in format strings):
+//   PW_CHECK_PTR_LE(a, b, msg, ...)  Asserts a <= b
+//   PW_CHECK_PTR_LT(a, b, msg, ...)  Asserts a <  b
+//   PW_CHECK_PTR_GE(a, b, msg, ...)  Asserts a >= b
+//   PW_CHECK_PTR_GT(a, b, msg, ...)  Asserts a >  b
+//   PW_CHECK_PTR_EQ(a, b, msg, ...)  Asserts a == b
+//   PW_CHECK_PTR_NE(a, b, msg, ...)  Asserts a != b
+//
+//   Binary comparison asserts for 'float' type ("%f" in format strings):
+//   PW_CHECK_FLOAT_NEAR(a, b, abs_tolerance, msg, ...)
+//     Asserts (a >= (b - abs_tolerance)) && (a <= (b + abs_tolerance))
+//   PW_CHECK_FLOAT_EXACT_LE(a, b, msg, ...)  Asserts a <= b
+//   PW_CHECK_FLOAT_EXACT_LT(a, b, msg, ...)  Asserts a <  b
+//   PW_CHECK_FLOAT_EXACT_GE(a, b, msg, ...)  Asserts a >= b
+//   PW_CHECK_FLOAT_EXACT_GT(a, b, msg, ...)  Asserts a >  b
+//   PW_CHECK_FLOAT_EXACT_EQ(a, b, msg, ...)  Asserts a == b
+//   PW_CHECK_FLOAT_EXACT_NE(a, b, msg, ...)  Asserts a != b
+//
+//   The above CHECK_*_*() are also available in DCHECK variants, which will
+//   only evaluate their arguments and trigger if the NDEBUG macro is defined.
+//
+//   Note: For float, proper comparator checks which take floating point
+//   precision and ergo error accumulation into account are not provided on
+//   purpose as this comes with some complexity and requires application
+//   specific tolerances in terms of Units of Least Precision (ULP). Instead,
+//   we recommend developers carefully consider how floating point precision and
+//   error impact the data they are bounding and whether CHECKs are appropriate.
+//
+//   Note: PW_CRASH is the equivalent of LOG_FATAL in other systems, where a
+//   device crash is triggered with a message. In Pigweed, logging and
+//   crashing/asserting are separated. There is a LOG_CRITICAL level in the
+//   logging module, but it does not have side effects; for LOG_FATAL, instead
+//   use this macro (PW_CRASH).
+//
+// The public macro definitions are split out into an impl file to facilitate
+// testing the facade logic directly, without going through the facade/backend
+// build facilities.
+#include "pw_assert/internal/check_impl.h"
+
+// For compatibility, include short.h if PW_ASSERT_USE_SHORT_NAMES is set.
+// TODO(pwbug/350): Remove this include and the PW_ASSERT_USE_SHORT_NAMES macro
+//     when projects have migrated to including the short.h header.
+#if defined(PW_ASSERT_USE_SHORT_NAMES) && PW_ASSERT_USE_SHORT_NAMES == 1
+#include "pw_assert/short.h"
+#endif  // defined(PW_ASSERT_USE_SHORT_NAMES) && PW_ASSERT_USE_SHORT_NAMES == 1
+
+// The pw_assert_backend must provide these macros:
+//
+//   PW_HANDLE_CRASH(msg, ...)
+//   PW_HANDLE_ASSERT_FAILURE(condition, msg, ...)
+//   PW_HANDLE_ASSERT_BINARY_COMPARE_FAILURE(a, op, b, type_fmt, msg, ...)
+//
+//   The low level functionality of triggering a crash, rebooting a device,
+//   collecting information, or hanging out in a while(1) loop, must be
+//   provided by the underlying assert backend as part of the crash or assert
+//   failure handling.
+//
+//   Note that for the assert failures, the handler should assume the assert
+//   has already failed (the facade checks the condition before delegating).
+//
+#include "pw_assert_backend/assert_backend.h"
diff --git a/pw_assert/public/pw_assert/internal/assert_impl.h b/pw_assert/public/pw_assert/internal/check_impl.h
index c13c29885..584dd0f33 100644
--- a/pw_assert/public/pw_assert/internal/assert_impl.h
+++ b/pw_assert/public/pw_assert/internal/check_impl.h
@@ -325,79 +325,3 @@
                                           "OK",                        \
                                           "%s",                        \
                                           __VA_ARGS__)
-
-// Define short, usable names if requested. Note that the CHECK() macro will
-// conflict with Google Log, which expects stream style logs.
-#ifndef PW_ASSERT_USE_SHORT_NAMES
-#define PW_ASSERT_USE_SHORT_NAMES 0
-#endif
-
-// =========================================================================
-// Short name definitions (optional)
-
-// clang-format off
-#if PW_ASSERT_USE_SHORT_NAMES
-
-// Checks that always run even in production.
-#define CRASH                 PW_CRASH
-#define CHECK                 PW_CHECK
-#define CHECK_PTR_LE          PW_CHECK_PTR_LE
-#define CHECK_PTR_LT          PW_CHECK_PTR_LT
-#define CHECK_PTR_GE          PW_CHECK_PTR_GE
-#define CHECK_PTR_GT          PW_CHECK_PTR_GT
-#define CHECK_PTR_EQ          PW_CHECK_PTR_EQ
-#define CHECK_PTR_NE          PW_CHECK_PTR_NE
-#define CHECK_NOTNULL         PW_CHECK_NOTNULL
-#define CHECK_INT_LE          PW_CHECK_INT_LE
-#define CHECK_INT_LT          PW_CHECK_INT_LT
-#define CHECK_INT_GE          PW_CHECK_INT_GE
-#define CHECK_INT_GT          PW_CHECK_INT_GT
-#define CHECK_INT_EQ          PW_CHECK_INT_EQ
-#define CHECK_INT_NE          PW_CHECK_INT_NE
-#define CHECK_UINT_LE         PW_CHECK_UINT_LE
-#define CHECK_UINT_LT         PW_CHECK_UINT_LT
-#define CHECK_UINT_GE         PW_CHECK_UINT_GE
-#define CHECK_UINT_GT         PW_CHECK_UINT_GT
-#define CHECK_UINT_EQ         PW_CHECK_UINT_EQ
-#define CHECK_UINT_NE         PW_CHECK_UINT_NE
-#define CHECK_FLOAT_NEAR      PW_CHECK_FLOAT_NEAR
-#define CHECK_FLOAT_EXACT_LE  PW_CHECK_FLOAT_EXACT_LE
-#define CHECK_FLOAT_EXACT_LT  PW_CHECK_FLOAT_EXACT_LT
-#define CHECK_FLOAT_EXACT_GE  PW_CHECK_FLOAT_EXACT_GE
-#define CHECK_FLOAT_EXACT_GT  PW_CHECK_FLOAT_EXACT_GT
-#define CHECK_FLOAT_EXACT_EQ  PW_CHECK_FLOAT_EXACT_EQ
-#define CHECK_FLOAT_EXACT_NE  PW_CHECK_FLOAT_EXACT_NE
-#define CHECK_OK              PW_CHECK_OK
-
-// Checks that are disabled if NDEBUG is not defined.
-#define DCHECK                PW_DCHECK
-#define DCHECK_PTR_LE         PW_DCHECK_PTR_LE
-#define DCHECK_PTR_LT         PW_DCHECK_PTR_LT
-#define DCHECK_PTR_GE         PW_DCHECK_PTR_GE
-#define DCHECK_PTR_GT         PW_DCHECK_PTR_GT
-#define DCHECK_PTR_EQ         PW_DCHECK_PTR_EQ
-#define DCHECK_PTR_NE         PW_DCHECK_PTR_NE
-#define DCHECK_NOTNULL        PW_DCHECK_NOTNULL
-#define DCHECK_INT_LE         PW_DCHECK_INT_LE
-#define DCHECK_INT_LT         PW_DCHECK_INT_LT
-#define DCHECK_INT_GE         PW_DCHECK_INT_GE
-#define DCHECK_INT_GT         PW_DCHECK_INT_GT
-#define DCHECK_INT_EQ         PW_DCHECK_INT_EQ
-#define DCHECK_INT_NE         PW_DCHECK_INT_NE
-#define DCHECK_UINT_LE        PW_DCHECK_UINT_LE
-#define DCHECK_UINT_LT        PW_DCHECK_UINT_LT
-#define DCHECK_UINT_GE        PW_DCHECK_UINT_GE
-#define DCHECK_UINT_GT        PW_DCHECK_UINT_GT
-#define DCHECK_UINT_EQ        PW_DCHECK_UINT_EQ
-#define DCHECK_UINT_NE        PW_DCHECK_UINT_NE
-#define DCHECK_FLOAT_NEAR     PW_DCHECK_FLOAT_NEAR
-#define DCHECK_FLOAT_EXACT_LT PW_DCHECK_FLOAT_EXACT_LT
-#define DCHECK_FLOAT_EXACT_LE PW_DCHECK_FLOAT_EXACT_LE
-#define DCHECK_FLOAT_EXACT_GT PW_DCHECK_FLOAT_EXACT_GT
-#define DCHECK_FLOAT_EXACT_GE PW_DCHECK_FLOAT_EXACT_GE
-#define DCHECK_FLOAT_EXACT_EQ PW_DCHECK_FLOAT_EXACT_EQ
-#define DCHECK_FLOAT_EXACT_NE PW_DCHECK_FLOAT_EXACT_NE
-#define DCHECK_OK             PW_DCHECK_OK
-
-#endif  // PW_ASSERT_SHORT_NAMES
-// clang-format on
diff --git a/pw_assert/public/pw_assert/light.h b/pw_assert/public/pw_assert/light.h
index 95457a8ba..635bb3f5d 100644
--- a/pw_assert/public/pw_assert/light.h
+++ b/pw_assert/public/pw_assert/light.h
@@ -1,4 +1,4 @@
-// Copyright 2020 The Pigweed Authors
+// Copyright 2021 The Pigweed Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License"); you may not
 // use this file except in compliance with the License. You may obtain a copy of
@@ -13,46 +13,5 @@
 // the License.
 #pragma once
 
-#include "pw_assert/options.h"  // For PW_ASSERT_ENABLE_DEBUG
-#include "pw_preprocessor/util.h"
-
-PW_EXTERN_C_START
-
-void pw_assert_HandleFailure(void);
-
-PW_EXTERN_C_END
-
-// A header- and constexpr-safe version of PW_CHECK().
-//
-// If the given condition is false, crash the system. Otherwise, do nothing.
-// The condition is guaranteed to be evaluated. This assert implementation is
-// guaranteed to be constexpr-safe.
-//
-// IMPORTANT: Unlike the PW_CHECK_*() suite of macros, this API captures no
-// rich information like line numbers, the file, expression arguments, or the
-// stringified expression. Use these macros only when absolutely necessary --
-// in headers, constexr contexts, or in rare cases where the call site overhead
-// of a full PW_CHECK must be avoided. Use PW_CHECK_*() whenever possible.
-#define PW_ASSERT(condition)     \
-  do {                           \
-    if (!(condition)) {          \
-      pw_assert_HandleFailure(); \
-    }                            \
-  } while (0)
-
-// A header- and constexpr-safe version of PW_DCHECK().
-//
-// Same as PW_ASSERT(), except that if PW_ASSERT_ENABLE_DEBUG == 1, the assert
-// is disabled and condition is not evaluated.
-//
-// IMPORTANT: Unlike the PW_CHECK_*() suite of macros, this API captures no
-// rich information like line numbers, the file, expression arguments, or the
-// stringified expression. Use these macros only when absolutely necessary --
-// in headers, constexr contexts, or in rare cases where the call site overhead
-// of a full PW_CHECK must be avoided. Use PW_DCHECK_*() whenever possible.
-#define PW_DASSERT(condition)                            \
-  do {                                                   \
-    if ((PW_ASSERT_ENABLE_DEBUG == 1) && !(condition)) { \
-      pw_assert_HandleFailure();                         \
-    }                                                    \
-  } while (0)
+// TODO(pwbug/350): Remove the deprecated light.h header in favor of assert.h.
+#include "pw_assert/assert.h"
diff --git a/pw_assert/public/pw_assert/short.h b/pw_assert/public/pw_assert/short.h
new file mode 100644
index 000000000..be4ed2d06
--- /dev/null
+++ b/pw_assert/public/pw_assert/short.h
@@ -0,0 +1,81 @@
+// Copyright 2021 The Pigweed Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+#pragma once
+
+#include "pw_assert/check.h"
+
+// Optional short CHECK name definitions
+
+// clang-format off
+// Checks that always run even in production.
+#define CRASH                 PW_CRASH
+#define CHECK                 PW_CHECK
+#define CHECK_PTR_LE          PW_CHECK_PTR_LE
+#define CHECK_PTR_LT          PW_CHECK_PTR_LT
+#define CHECK_PTR_GE          PW_CHECK_PTR_GE
+#define CHECK_PTR_GT          PW_CHECK_PTR_GT
+#define CHECK_PTR_EQ          PW_CHECK_PTR_EQ
+#define CHECK_PTR_NE          PW_CHECK_PTR_NE
+#define CHECK_NOTNULL         PW_CHECK_NOTNULL
+#define CHECK_INT_LE          PW_CHECK_INT_LE
+#define CHECK_INT_LT          PW_CHECK_INT_LT
+#define CHECK_INT_GE          PW_CHECK_INT_GE
+#define CHECK_INT_GT          PW_CHECK_INT_GT
+#define CHECK_INT_EQ          PW_CHECK_INT_EQ
+#define CHECK_INT_NE          PW_CHECK_INT_NE
+#define CHECK_UINT_LE         PW_CHECK_UINT_LE
+#define CHECK_UINT_LT         PW_CHECK_UINT_LT
+#define CHECK_UINT_GE         PW_CHECK_UINT_GE
+#define CHECK_UINT_GT         PW_CHECK_UINT_GT
+#define CHECK_UINT_EQ         PW_CHECK_UINT_EQ
+#define CHECK_UINT_NE         PW_CHECK_UINT_NE
+#define CHECK_FLOAT_NEAR      PW_CHECK_FLOAT_NEAR
+#define CHECK_FLOAT_EXACT_LE  PW_CHECK_FLOAT_EXACT_LE
+#define CHECK_FLOAT_EXACT_LT  PW_CHECK_FLOAT_EXACT_LT
+#define CHECK_FLOAT_EXACT_GE  PW_CHECK_FLOAT_EXACT_GE
+#define CHECK_FLOAT_EXACT_GT  PW_CHECK_FLOAT_EXACT_GT
+#define CHECK_FLOAT_EXACT_EQ  PW_CHECK_FLOAT_EXACT_EQ
+#define CHECK_FLOAT_EXACT_NE  PW_CHECK_FLOAT_EXACT_NE
+#define CHECK_OK              PW_CHECK_OK
+
+// Checks that are disabled if NDEBUG is not defined.
+#define DCHECK                PW_DCHECK
+#define DCHECK_PTR_LE         PW_DCHECK_PTR_LE
+#define DCHECK_PTR_LT         PW_DCHECK_PTR_LT
+#define DCHECK_PTR_GE         PW_DCHECK_PTR_GE
+#define DCHECK_PTR_GT         PW_DCHECK_PTR_GT
+#define DCHECK_PTR_EQ         PW_DCHECK_PTR_EQ
+#define DCHECK_PTR_NE         PW_DCHECK_PTR_NE
+#define DCHECK_NOTNULL        PW_DCHECK_NOTNULL
+#define DCHECK_INT_LE         PW_DCHECK_INT_LE
+#define DCHECK_INT_LT         PW_DCHECK_INT_LT
+#define DCHECK_INT_GE         PW_DCHECK_INT_GE
+#define DCHECK_INT_GT         PW_DCHECK_INT_GT
+#define DCHECK_INT_EQ         PW_DCHECK_INT_EQ
+#define DCHECK_INT_NE         PW_DCHECK_INT_NE
+#define DCHECK_UINT_LE        PW_DCHECK_UINT_LE
+#define DCHECK_UINT_LT        PW_DCHECK_UINT_LT
+#define DCHECK_UINT_GE        PW_DCHECK_UINT_GE
+#define DCHECK_UINT_GT        PW_DCHECK_UINT_GT
+#define DCHECK_UINT_EQ        PW_DCHECK_UINT_EQ
+#define DCHECK_UINT_NE        PW_DCHECK_UINT_NE
+#define DCHECK_FLOAT_NEAR     PW_DCHECK_FLOAT_NEAR
+#define DCHECK_FLOAT_EXACT_LT PW_DCHECK_FLOAT_EXACT_LT
+#define DCHECK_FLOAT_EXACT_LE PW_DCHECK_FLOAT_EXACT_LE
+#define DCHECK_FLOAT_EXACT_GT PW_DCHECK_FLOAT_EXACT_GT
+#define DCHECK_FLOAT_EXACT_GE PW_DCHECK_FLOAT_EXACT_GE
+#define DCHECK_FLOAT_EXACT_EQ PW_DCHECK_FLOAT_EXACT_EQ
+#define DCHECK_FLOAT_EXACT_NE PW_DCHECK_FLOAT_EXACT_NE
+#define DCHECK_OK             PW_DCHECK_OK
+// clang-format on