Generate build information from CHANGES.md

This PR significantly reworks the way glslang is versioned.

Instead of committing changes to the `GLSLANG_MINOR_VERSION` define in
`glslang/Public/ShaderLang.h`, and using `make-revision` to generate
`GLSLANG_PATCH_LEVEL` in `glslang/Include/revision.h`, all version
information is now derived from the new `CHANGES.md` file.

`CHANGES.md` acts as the single source of truth for glslang version
information, along with a convenient place to put all release notes for
each notable change made.

`CHANGES.md` is parsed using the new `build_info.py` python script.
This script can read basic template files to produce new source files,
which it does to read the new `build_info.h.tmpl` to generate (at build
time) a glslang private header at
`<build-dir>/include/glslang/build_info.h`.
I've written generators for each of the CMake, Bazel, gn, and
`Android.mk` build scripts.

The new version code conforms to the Semantic Versioning 2.0 spec.

This new version is also used by the CMake rules to produce versioned
shared objects, including a major-versioned SONAME.

New APIs:
---------

* `glslang::GetVersion()` returns a `Version` struct with the version
  major, minor, patch and flavor.

Breaking API changes:
---------------------

* The public defines `GLSLANG_MINOR_VERSION` and `GLSLANG_PATCH_LEVEL`
  have been entirely removed.
* `glslang/Public/ShaderLang.h` and `glslang/Include/revision.h` have
  been deleted.
* Instead, `<build-dir>/include/glslang/build_info.h` is created in
  the build directory, and `<build-dir>/include` is a CMake `PUBLIC`
  (dependee-inherited) include directory for the glslang targets.
* `<build-dir>/include/glslang/build_info.h` contains the following
   new #defines:
   `GLSLANG_VERSION_MAJOR`, `GLSLANG_VERSION_MINOR`,
   `GLSLANG_VERSION_PATCH`, `GLSLANG_VERSION_FLAVOR`,
   `GLSLANG_VERSION_GREATER_THAN(major, minor, patch)`,
   `GLSLANG_VERSION_GREATER_OR_EQUAL_TO(major, minor, patch)`,
   `GLSLANG_VERSION_LESS_THAN(major, minor, patch)`,
   `GLSLANG_VERSION_LESS_OR_EQUAL_TO(major, minor, patch)`
*  The CMake install output directory contains a copy of
   `build_info.h` at: `include/glslang/build_info.h`
*  Python3 is now always required to build glslang (likely always
   required for transitive dependency builds).

Android.mk

@@ -33,6 +33,24 @@
 
 LOCAL_PATH := $(call my-dir)
 
+# Generate glslang/build_info.h
+GLSLANG_GENERATED_INCLUDEDIR:=$(TARGET_OUT)/include
+GLSLANG_BUILD_INFO_H:=$(GLSLANG_GENERATED_INCLUDEDIR)/glslang/build_info.h
+
+define gen_glslang_build_info_h
+$(call generate-file-dir,$(GLSLANG_GENERATED_INCLUDEDIR)/dummy_filename)
+$(GLSLANG_BUILD_INFO_H): \
+		$(LOCAL_PATH)/build_info.py \
+		$(LOCAL_PATH)/build_info.h.tmpl \
+		$(LOCAL_PATH)/CHANGES.md
+		@$(HOST_PYTHON) $(LOCAL_PATH)/build_info.py \
+						$(LOCAL_PATH) \
+						-i $(LOCAL_PATH)/build_info.h.tmpl \
+						-o $(GLSLANG_BUILD_INFO_H)
+		@echo "[$(TARGET_ARCH_ABI)] Generate       : $(GLSLANG_BUILD_INFO_H) <= CHANGES.md"
+endef
+$(eval $(call gen_glslang_build_info_h))
+
 GLSLANG_OS_FLAGS := -DGLSLANG_OSINCLUDE_UNIX
 # AMD and NV extensions are turned on by default in upstream Glslang.
 GLSLANG_DEFINES:= -DAMD_EXTENSIONS -DNV_EXTENSIONS -DENABLE_HLSL $(GLSLANG_OS_FLAGS)
@@ -55,18 +73,14 @@ LOCAL_C_INCLUDES:=$(LOCAL_PATH)/OGLCompiler
 LOCAL_STATIC_LIBRARIES:=OSDependent
 include $(BUILD_STATIC_LIBRARY)
 
-# Build Glslang's HLSL parser library.
+# Build the stubbed HLSL library.
+# The HLSL source is now directly referenced by the glslang static library
+# instead.
 include $(CLEAR_VARS)
 LOCAL_MODULE:=HLSL
 LOCAL_CXXFLAGS:=-std=c++11 -fno-exceptions -fno-rtti $(GLSLANG_DEFINES)
 LOCAL_SRC_FILES:= \
-		glslang/HLSL/hlslAttributes.cpp \
-		glslang/HLSL/hlslGrammar.cpp \
-		glslang/HLSL/hlslOpMap.cpp \
-		glslang/HLSL/hlslParseables.cpp \
-		glslang/HLSL/hlslParseHelper.cpp \
-		glslang/HLSL/hlslScanContext.cpp \
-		glslang/HLSL/hlslTokenStream.cpp
+	hlsl/stub.cpp
 LOCAL_C_INCLUDES:=$(LOCAL_PATH) \
 	$(LOCAL_PATH)/glslang/HLSL
 include $(BUILD_STATIC_LIBRARY)
@@ -74,12 +88,23 @@ include $(BUILD_STATIC_LIBRARY)
 include $(CLEAR_VARS)
 GLSLANG_OUT_PATH=$(if $(call host-path-is-absolute,$(TARGET_OUT)),$(TARGET_OUT),$(abspath $(TARGET_OUT)))
 
+# ShaderLang.cpp depends on the generated build_info.h
+$(LOCAL_PATH)/glslang/MachineIndependent/ShaderLang.cpp: \
+	$(GLSLANG_BUILD_INFO_H)
+
 LOCAL_MODULE:=glslang
 LOCAL_CXXFLAGS:=-std=c++11 -fno-exceptions -fno-rtti $(GLSLANG_DEFINES)
 LOCAL_EXPORT_C_INCLUDES:=$(LOCAL_PATH)
 LOCAL_SRC_FILES:= \
 		glslang/GenericCodeGen/CodeGen.cpp \
 		glslang/GenericCodeGen/Link.cpp \
+		glslang/HLSL/hlslAttributes.cpp \
+		glslang/HLSL/hlslGrammar.cpp \
+		glslang/HLSL/hlslOpMap.cpp \
+		glslang/HLSL/hlslParseables.cpp \
+		glslang/HLSL/hlslParseHelper.cpp \
+		glslang/HLSL/hlslScanContext.cpp \
+		glslang/HLSL/hlslTokenStream.cpp \
 		glslang/MachineIndependent/attribute.cpp \
 		glslang/MachineIndependent/Constant.cpp \
 		glslang/MachineIndependent/glslang_tab.cpp \
@@ -109,14 +134,19 @@ LOCAL_SRC_FILES:= \
 		glslang/MachineIndependent/preprocessor/PpTokens.cpp
 LOCAL_C_INCLUDES:=$(LOCAL_PATH) \
 	$(LOCAL_PATH)/glslang/MachineIndependent \
+	$(GLSLANG_GENERATED_INCLUDEDIR) \
 	$(GLSLANG_OUT_PATH)
 LOCAL_STATIC_LIBRARIES:=OSDependent OGLCompiler HLSL
 include $(BUILD_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
+
+# GlslangToSpv.cpp depends on the generated build_info.h
+$(LOCAL_PATH)/SPIRV/GlslangToSpv.cpp: \
+	$(GLSLANG_BUILD_INFO_H)
+
 LOCAL_MODULE:=SPIRV
 LOCAL_CXXFLAGS:=-std=c++11 -fno-exceptions -fno-rtti -Werror $(GLSLANG_DEFINES)
-LOCAL_EXPORT_C_INCLUDES:=$(LOCAL_PATH)
 LOCAL_SRC_FILES:= \
 	SPIRV/GlslangToSpv.cpp \
 	SPIRV/InReadableOrder.cpp \
@@ -127,7 +157,9 @@ LOCAL_SRC_FILES:= \
 	SPIRV/SpvTools.cpp \
 	SPIRV/disassemble.cpp \
 	SPIRV/doc.cpp
-LOCAL_C_INCLUDES:=$(LOCAL_PATH) $(LOCAL_PATH)/glslang/SPIRV
+LOCAL_C_INCLUDES:=$(LOCAL_PATH) \
+	$(LOCAL_PATH)/glslang/SPIRV \
+	$(GLSLANG_GENERATED_INCLUDEDIR)
 LOCAL_EXPORT_C_INCLUDES:=$(LOCAL_PATH)/glslang/SPIRV
 LOCAL_STATIC_LIBRARIES:=glslang
 include $(BUILD_STATIC_LIBRARY)

BUILD.bazel

@@ -43,6 +43,20 @@ licenses(["notice"])
 
 exports_files(["LICENSE"])
 
+# Build information generation script
+py_binary(
+    name = "build_info",
+    srcs = ["build_info.py"],
+)
+
+genrule(
+    name = "gen_build_info_h",
+    srcs = ["CHANGES.md", "build_info.h.tmpl"],
+    outs = ["glslang/build_info.h"],
+    cmd = "$(location build_info) $$(dirname $(location CHANGES.md)) -i $(location build_info.h.tmpl) -o $(location glslang/build_info.h)",
+    tools = [":build_info"],
+)
+
 COMMON_COPTS = select({
     "@bazel_tools//src/conditions:windows": [""],
     "//conditions:default": [
@@ -93,6 +107,7 @@ cc_library(
         "StandAlone/DirStackFileIncluder.h",
         "glslang/OSDependent/osinclude.h",
         "glslang/Public/ShaderLang.h",
+        ":gen_build_info_h",
     ],
     copts = COMMON_COPTS,
     defines = [

BUILD.gn

@@ -46,6 +46,29 @@ if (defined(is_fuchsia_tree) && is_fuchsia_tree) {
   _configs_to_add = [ "//build/config/compiler:no_chromium_code" ]
 }
 
+action("glslang_build_info") {
+  script = "build_info.py"
+
+  src_dir = "."
+  changes_file = "CHANGES.md"
+  template_file = "build_info.h.tmpl"
+  out_file = "${target_gen_dir}/include/glslang/build_info.h"
+
+  inputs = [
+    changes_file,
+    script,
+    template_file,
+  ]
+  outputs = [
+    out_file
+  ]
+  args = [
+    rebase_path(src_dir, root_build_dir),
+    "-i", rebase_path(template_file, root_build_dir),
+    "-o", rebase_path(out_file, root_build_dir),
+  ]
+}
+
 spirv_tools_dir = glslang_spirv_tools_dir
 if (!defined(glslang_angle)) {
   glslang_angle = false
@@ -109,7 +132,6 @@ template("glslang_sources_common") {
       "glslang/Include/Types.h",
       "glslang/Include/arrays.h",
       "glslang/Include/intermediate.h",
-      "glslang/Include/revision.h",
       "glslang/MachineIndependent/Constant.cpp",
       "glslang/MachineIndependent/InfoSink.cpp",
       "glslang/MachineIndependent/Initialize.cpp",
@@ -216,13 +238,18 @@ template("glslang_sources_common") {
       ]
     }
 
+    deps = [ ":glslang_build_info" ]
+
     if (invoker.enable_opt) {
-      deps = [
+      deps += [
+        ":glslang_build_info",
         "${spirv_tools_dir}:spvtools_opt",
         "${spirv_tools_dir}:spvtools_val",
       ]
     }
 
+    include_dirs = [ "${target_gen_dir}/include" ]
+
     configs -= _configs_to_remove
     configs += _configs_to_add
   }
@@ -265,6 +292,8 @@ executable("glslang_validator") {
   ]
   public_configs = [ ":glslang_hlsl" ]
 
+  include_dirs = [ "${target_gen_dir}/include" ]
+
   configs -= _configs_to_remove
   configs += _configs_to_add
 }

CHANGES.md

@@ -0,0 +1,24 @@
+# Revision history for `glslang`
+
+All notable changes to this project will be documented in this file.
+This project adheres to [Semantic Versioning](https://semver.org/).
+
+## 10.15.3847-dev 2020-06-16
+
+### Breaking changes
+
+* The following files have been removed:
+  * `glslang/include/revision.h`
+  * `glslang/include/revision.template`
+
+The `GLSLANG_MINOR_VERSION` and `GLSLANG_PATCH_LEVEL` defines have been removed
+from the public headers. \
+Instead each build script now uses the new `build_info.py`
+script along with the `build_info.h.tmpl` and this `CHANGES.md` file to generate
+the glslang build-time generated header `glslang/build_info.h`.
+
+The new public API to obtain the `glslang` version is `glslang::GetVersion()`.
+
+### Other changes
+* `glslang` shared objects produced by CMake are now `SONAME` versioned using
+   [Semantic Versioning 2.0.0](https://semver.org/).

CMakeLists.txt

@@ -57,6 +57,14 @@ if(BUILD_SHARED_LIBS)
     set(LIB_TYPE SHARED)
 endif()
 
+if ("${CMAKE_BUILD_TYPE}" STREQUAL "")
+    # This logic inside SPIRV-Tools, which can upset build target dependencies
+    # if changed after targets are already defined. To prevent these issues,
+    # ensure CMAKE_BUILD_TYPE is assigned early and at the glslang root scope.
+    message(STATUS "No build type selected, default to Debug")
+    set(CMAKE_BUILD_TYPE "Debug")
+endif()
+
 option(SKIP_GLSLANG_INSTALL "Skip installation" ${SKIP_GLSLANG_INSTALL})
 if(NOT ${SKIP_GLSLANG_INSTALL})
   set(ENABLE_GLSLANG_INSTALL ON)
@@ -221,12 +229,54 @@ endfunction(glslang_set_link_args)
 
 # CMake needs to find the right version of python, right from the beginning,
 # otherwise, it will find the wrong version and fail later
-if(BUILD_EXTERNAL AND IS_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/External)
-    find_package(PythonInterp 3 REQUIRED)
-
-	# We depend on these for later projects, so they should come first.
-	add_subdirectory(External)
-endif()
+find_package(PythonInterp 3 REQUIRED)
+
+# Root directory for build-time generated include files
+set(GLSLANG_GENERATED_INCLUDEDIR "${CMAKE_BINARY_DIR}/include")
+
+################################################################################
+# Build version information generation
+################################################################################
+set(GLSLANG_CHANGES_FILE      "${CMAKE_SOURCE_DIR}/CHANGES.md")
+set(GLSLANG_BUILD_INFO_PY     "${CMAKE_SOURCE_DIR}/build_info.py")
+set(GLSLANG_BUILD_INFO_H_TMPL "${CMAKE_SOURCE_DIR}/build_info.h.tmpl")
+set(GLSLANG_BUILD_INFO_H      "${GLSLANG_GENERATED_INCLUDEDIR}/glslang/build_info.h")
+
+# Command to build the build_info.h file
+add_custom_command(
+    OUTPUT  ${GLSLANG_BUILD_INFO_H}
+    COMMAND ${PYTHON_EXECUTABLE} "${GLSLANG_BUILD_INFO_PY}"
+            ${CMAKE_CURRENT_SOURCE_DIR}
+            "-i" ${GLSLANG_BUILD_INFO_H_TMPL}
+            "-o" ${GLSLANG_BUILD_INFO_H}
+    DEPENDS ${GLSLANG_BUILD_INFO_PY}
+            ${GLSLANG_CHANGES_FILE}
+            ${GLSLANG_BUILD_INFO_H_TMPL}
+    COMMENT "Generating ${GLSLANG_BUILD_INFO_H}")
+
+# Target to build the build_info.h file
+add_custom_target(glslang-build-info DEPENDS ${GLSLANG_BUILD_INFO_H})
+
+# Populate the CMake GLSLANG_VERSION* variables with the build version
+# information.
+execute_process(
+    COMMAND ${PYTHON_EXECUTABLE} "${GLSLANG_BUILD_INFO_PY}"
+            ${CMAKE_CURRENT_SOURCE_DIR} "<major>.<minor>.<patch><-flavor>;<major>;<minor>;<patch>;<flavor>"
+    OUTPUT_VARIABLE "GLSLANG_VERSIONS"
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+list(GET "GLSLANG_VERSIONS" 0 "GLSLANG_VERSION")
+list(GET "GLSLANG_VERSIONS" 1 "GLSLANG_VERSION_MAJOR")
+list(GET "GLSLANG_VERSIONS" 2 "GLSLANG_VERSION_MINOR")
+list(GET "GLSLANG_VERSIONS" 3 "GLSLANG_VERSION_PATCH")
+list(GET "GLSLANG_VERSIONS" 4 "GLSLANG_VERSION_FLAVOR")
+configure_file(${GLSLANG_CHANGES_FILE} "${CMAKE_CURRENT_BINARY_DIR}/CHANGES.md") # Required to re-run cmake on version change
+
+# glslang_add_build_info_dependency() adds the glslang-build-info dependency and
+# generated include directories to target.
+function(glslang_add_build_info_dependency target)
+    target_include_directories(${target} PUBLIC $<BUILD_INTERFACE:${GLSLANG_GENERATED_INCLUDEDIR}>)
+    add_dependencies(${target} glslang-build-info)
+endfunction()
 
 # glslang_only_export_explicit_symbols() makes the symbol visibility hidden by
 # default for <target> when building shared libraries, and sets the
@@ -256,6 +306,11 @@ else()
     message(NOTICE "Your CMake version is ${CMAKE_VERSION}. Update to at least 3.16 to enable precompiled headers to speed up incremental builds")
 endif()
 
+if(BUILD_EXTERNAL AND IS_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/External)
+    # We depend on these for later projects, so they should come first.
+    add_subdirectory(External)
+endif()
+
 if(NOT TARGET SPIRV-Tools-opt)
     set(ENABLE_OPT OFF)
 endif()

SPIRV/CMakeLists.txt

@@ -72,8 +72,10 @@ add_library(SPIRV ${LIB_TYPE} ${SOURCES} ${HEADERS})
 set_property(TARGET SPIRV PROPERTY FOLDER glslang)
 set_property(TARGET SPIRV PROPERTY POSITION_INDEPENDENT_CODE ON)
 target_include_directories(SPIRV PUBLIC
-	$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/..>
-	$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/..>
+    $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
+
+glslang_add_build_info_dependency(SPIRV)
 
 if (ENABLE_SPVREMAPPER)
     add_library(SPVRemapper ${LIB_TYPE} ${SPVREMAP_SOURCES} ${SPVREMAP_HEADERS})
@@ -95,8 +97,8 @@ if(ENABLE_OPT)
     )
     target_link_libraries(SPIRV PRIVATE MachineIndependent SPIRV-Tools-opt)
     target_include_directories(SPIRV PUBLIC
-		$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/../External>
-		$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/External>)
+        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/../External>
+        $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/External>)
 else()
     target_link_libraries(SPIRV PRIVATE MachineIndependent)
 endif(ENABLE_OPT)

SPIRV/GlslangToSpv.cpp

@@ -56,7 +56,9 @@ namespace spv {
 #include "../glslang/MachineIndependent/localintermediate.h"
 #include "../glslang/MachineIndependent/SymbolTable.h"
 #include "../glslang/Include/Common.h"
-#include "../glslang/Include/revision.h"
+
+// Build-time generated includes
+#include "glslang/build_info.h"
 
 #include <fstream>
 #include <iomanip>
@@ -8689,9 +8691,10 @@ void OutputSpvHex(const std::vector<unsigned int>& spirv, const char* baseName,
     out.open(baseName, std::ios::binary | std::ios::out);
     if (out.fail())
         printf("ERROR: Failed to open file: %s\n", baseName);
-    out << "\t// " << 
-        GetSpirvGeneratorVersion() << "." << GLSLANG_MINOR_VERSION << "." << GLSLANG_PATCH_LEVEL <<
-        std::endl;
+    out << "\t// " <<
+        GetSpirvGeneratorVersion() <<
+        GLSLANG_VERSION_MAJOR << "." << GLSLANG_VERSION_MINOR << "." << GLSLANG_VERSION_PATCH <<
+        GLSLANG_VERSION_FLAVOR << std::endl;
     if (varName != nullptr) {
         out << "\t #pragma once" << std::endl;
         out << "const uint32_t " << varName << "[] = {" << std::endl;

StandAlone/StandAlone.cpp

@@ -44,7 +44,6 @@
 #include "Worklist.h"
 #include "DirStackFileIncluder.h"
 #include "./../glslang/Include/ShHandle.h"
-#include "./../glslang/Include/revision.h"
 #include "./../glslang/Public/ShaderLang.h"
 #include "../SPIRV/GlslangToSpv.h"
 #include "../SPIRV/GLSL.std.450.h"
@@ -62,6 +61,9 @@
 
 #include "../glslang/OSDependent/osinclude.h"
 
+// Build-time generated includes
+#include "glslang/build_info.h"
+
 extern "C" {
     GLSLANG_EXPORT void ShOutputHtml();
 }
@@ -1278,13 +1280,13 @@ int singleMain()
 #endif
 
     if (Options & EOptionDumpBareVersion) {
-        printf("%d.%d.%d\n",
-            glslang::GetSpirvGeneratorVersion(), GLSLANG_MINOR_VERSION, GLSLANG_PATCH_LEVEL);
+        printf("%d:%d.%d.%d%s\n", glslang::GetSpirvGeneratorVersion(), GLSLANG_VERSION_MAJOR, GLSLANG_VERSION_MINOR,
+                GLSLANG_VERSION_PATCH, GLSLANG_VERSION_FLAVOR);
         if (workList.empty())
             return ESuccess;
     } else if (Options & EOptionDumpVersions) {
-        printf("Glslang Version: %d.%d.%d\n",
-            glslang::GetSpirvGeneratorVersion(), GLSLANG_MINOR_VERSION, GLSLANG_PATCH_LEVEL);
+        printf("Glslang Version: %d:%d.%d.%d%s\n", glslang::GetSpirvGeneratorVersion(), GLSLANG_VERSION_MAJOR,
+                GLSLANG_VERSION_MINOR, GLSLANG_VERSION_PATCH, GLSLANG_VERSION_FLAVOR);
         printf("ESSL Version: %s\n", glslang::GetEsslVersionString());
         printf("GLSL Version: %s\n", glslang::GetGlslVersionString());
         std::string spirvVersion;

build_info.h.tmpl

@@ -0,0 +1,62 @@
+// Copyright (C) 2020 The Khronos Group Inc.
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+//
+//    Redistributions of source code must retain the above copyright
+//    notice, this list of conditions and the following disclaimer.
+//
+//    Redistributions in binary form must reproduce the above
+//    copyright notice, this list of conditions and the following
+//    disclaimer in the documentation and/or other materials provided
+//    with the distribution.
+//
+//    Neither the name of The Khronos Group Inc. nor the names of its
+//    contributors may be used to endorse or promote products derived
+//    from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+// COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef GLSLANG_BUILD_INFO
+#define GLSLANG_BUILD_INFO
+
+#define GLSLANG_VERSION_MAJOR <major>
+#define GLSLANG_VERSION_MINOR <minor>
+#define GLSLANG_VERSION_PATCH <patch>
+#define GLSLANG_VERSION_FLAVOR "<flavor>"
+
+#define GLSLANG_VERSION_GREATER_THAN(major, minor, patch) \
+    (((major) > GLSLANG_VERSION_MAJOR) || ((major) == GLSLANG_VERSION_MAJOR && \
+    (((minor) > GLSLANG_VERSION_MINOR) || ((minor) == GLSLANG_VERSION_MINOR && \
+     ((patch) > GLSLANG_VERSION_PATCH)))))
+
+#define GLSLANG_VERSION_GREATER_OR_EQUAL_TO(major, minor, patch) \
+    (((major) > GLSLANG_VERSION_MAJOR) || ((major) == GLSLANG_VERSION_MAJOR && \
+    (((minor) > GLSLANG_VERSION_MINOR) || ((minor) == GLSLANG_VERSION_MINOR && \
+     ((patch) >= GLSLANG_VERSION_PATCH)))))
+
+#define GLSLANG_VERSION_LESS_THAN(major, minor, patch) \
+    (((major) < GLSLANG_VERSION_MAJOR) || ((major) == GLSLANG_VERSION_MAJOR && \
+    (((minor) < GLSLANG_VERSION_MINOR) || ((minor) == GLSLANG_VERSION_MINOR && \
+     ((patch) < GLSLANG_VERSION_PATCH)))))
+
+#define GLSLANG_VERSION_LESS_OR_EQUAL_TO(major, minor, patch) \
+    (((major) < GLSLANG_VERSION_MAJOR) || ((major) == GLSLANG_VERSION_MAJOR && \
+    (((minor) < GLSLANG_VERSION_MINOR) || ((minor) == GLSLANG_VERSION_MINOR && \
+     ((patch) <= GLSLANG_VERSION_PATCH)))))
+
+#endif // GLSLANG_BUILD_INFO

build_info.py

@@ -0,0 +1,223 @@
+#!/usr/bin/env python
+
+# Copyright (c) 2020 Google Inc.
+#
+# 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
+#
+#     http://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.
+
+import datetime
+import errno
+import os
+import os.path
+import re
+import subprocess
+import sys
+import time
+
+usage = """{} emits a string to stdout or file with project version information.
+
+args: <project-dir> [<input-string>] [-i <input-file>] [-o <output-file>]
+
+Either <input-string> or -i <input-file> needs to be provided.
+
+The tool will output the provided string or file content with the following
+tokens substituted:
+
+ <major>   - The major version point parsed from the CHANGES.md file.
+ <minor>   - The minor version point parsed from the CHANGES.md file.
+ <patch>   - The point version point parsed from the CHANGES.md file.
+ <flavor>  - The optional dash suffix parsed from the CHANGES.md file (excluding
+             dash prefix).
+ <-flavor> - The optional dash suffix parsed from the CHANGES.md file (including
+             dash prefix).
+ <date>    - The optional date of the release in the form YYYY-MM-DD
+ <commit>  - The git commit information for the directory taken from
+             "git describe" if that succeeds, or "git rev-parse HEAD"
+             if that succeeds, or otherwise a message containing the phrase
+             "unknown hash".
+
+-o is an optional flag for writing the output string to the given file. If
+   ommitted then the string is printed to stdout.
+"""
+
+def mkdir_p(directory):
+    """Make the directory, and all its ancestors as required.  Any of the
+    directories are allowed to already exist."""
+
+    if directory == "":
+        # We're being asked to make the current directory.
+        return
+
+    try:
+        os.makedirs(directory)
+    except OSError as e:
+        if e.errno == errno.EEXIST and os.path.isdir(directory):
+            pass
+        else:
+            raise
+
+
+def command_output(cmd, directory):
+    """Runs a command in a directory and returns its standard output stream.
+
+    Captures the standard error stream.
+
+    Raises a RuntimeError if the command fails to launch or otherwise fails.
+    """
+    p = subprocess.Popen(cmd,
+                         cwd=directory,
+                         stdout=subprocess.PIPE,
+                         stderr=subprocess.PIPE)
+    (stdout, _) = p.communicate()
+    if p.returncode != 0:
+        raise RuntimeError('Failed to run %s in %s' % (cmd, directory))
+    return stdout
+
+
+def deduce_software_version(directory):
+    """Returns a software version number parsed from the CHANGES.md file
+    in the given directory.
+
+    The CHANGES.md file describes most recent versions first.
+    """
+
+    # Match the first well-formed version-and-date line.
+    # Allow trailing whitespace in the checked-out source code has
+    # unexpected carriage returns on a linefeed-only system such as
+    # Linux.
+    pattern = re.compile(r'^#* +(\d+)\.(\d+)\.(\d+)(-\w+)? (\d\d\d\d-\d\d-\d\d)? *$')
+    changes_file = os.path.join(directory, 'CHANGES.md')
+    with open(changes_file, mode='r') as f:
+        for line in f.readlines():
+            match = pattern.match(line)
+            if match:
+                return {
+                    "major": match.group(1),
+                    "minor": match.group(2),
+                    "patch": match.group(3),
+                    "flavor": match.group(4).lstrip("-"),
+                    "-flavor": match.group(4),
+                    "date": match.group(5),
+                }
+    raise Exception('No version number found in {}'.format(changes_file))
+
+
+def describe(directory):
+    """Returns a string describing the current Git HEAD version as descriptively
+    as possible.
+
+    Runs 'git describe', or alternately 'git rev-parse HEAD', in directory.  If
+    successful, returns the output; otherwise returns 'unknown hash, <date>'."""
+    try:
+        # decode() is needed here for Python3 compatibility. In Python2,
+        # str and bytes are the same type, but not in Python3.
+        # Popen.communicate() returns a bytes instance, which needs to be
+        # decoded into text data first in Python3. And this decode() won't
+        # hurt Python2.
+        return command_output(['git', 'describe'], directory).rstrip().decode()
+    except:
+        try:
+            return command_output(
+                ['git', 'rev-parse', 'HEAD'], directory).rstrip().decode()
+        except:
+            # This is the fallback case where git gives us no information,
+            # e.g. because the source tree might not be in a git tree.
+            # In this case, usually use a timestamp.  However, to ensure
+            # reproducible builds, allow the builder to override the wall
+            # clock time with environment variable SOURCE_DATE_EPOCH
+            # containing a (presumably) fixed timestamp.
+            timestamp = int(os.environ.get('SOURCE_DATE_EPOCH', time.time()))
+            formatted = datetime.datetime.utcfromtimestamp(timestamp).isoformat()
+            return 'unknown hash, {}'.format(formatted)
+
+def parse_args():
+    directory = None
+    input_string = None
+    input_file = None
+    output_file = None
+
+    if len(sys.argv) < 2:
+        raise Exception("Invalid number of arguments")
+
+    directory = sys.argv[1]
+    i = 2
+
+    if not sys.argv[i].startswith("-"):
+        input_string = sys.argv[i]
+        i = i + 1
+
+    while i < len(sys.argv):
+        opt = sys.argv[i]
+        i = i + 1
+
+        if opt == "-i" or opt == "-o":
+            if i == len(sys.argv):
+                raise Exception("Expected path after {}".format(opt))
+            val = sys.argv[i]
+            i = i + 1
+            if (opt == "-i"):
+                input_file = val
+            elif (opt == "-o"):
+                output_file = val
+            else:
+                raise Exception("Unknown flag {}".format(opt))
+
+    return {
+        "directory": directory,
+        "input_string": input_string,
+        "input_file": input_file,
+        "output_file": output_file,
+    }
+
+def main():
+    args = None
+    try:
+        args = parse_args()
+    except Exception as e:
+        print(e)
+        print("\nUsage:\n")
+        print(usage.format(sys.argv[0]))
+        sys.exit(1)
+
+    directory = args["directory"]
+    template = args["input_string"]
+    if template == None:
+        with open(args["input_file"], 'r') as f:
+            template = f.read()
+    output_file = args["output_file"]
+
+    software_version = deduce_software_version(directory)
+    commit = describe(directory)
+    output = template \
+        .replace("<major>", software_version["major"]) \
+        .replace("<minor>", software_version["minor"]) \
+        .replace("<patch>", software_version["patch"]) \
+        .replace("<flavor>", software_version["flavor"]) \
+        .replace("<-flavor>", software_version["-flavor"]) \
+        .replace("<date>", software_version["date"]) \
+        .replace("<commit>", commit)
+
+    if output_file is None:
+        print(output)
+    else:
+        mkdir_p(os.path.dirname(output_file))
+
+        if os.path.isfile(output_file):
+            with open(output_file, 'r') as f:
+                if output == f.read():
+                    return
+
+        with open(output_file, 'w') as f:
+            f.write(output)
+
+if __name__ == '__main__':
+    main()

glslang/CMakeLists.txt

@@ -133,6 +133,9 @@ endif(ENABLE_HLSL)
 add_library(MachineIndependent STATIC ${MACHINEINDEPENDENT_SOURCES} ${MACHINEINDEPENDENT_HEADERS})
 set_property(TARGET MachineIndependent PROPERTY POSITION_INDEPENDENT_CODE ON)
 set_property(TARGET MachineIndependent PROPERTY FOLDER glslang)
+
+glslang_add_build_info_dependency(MachineIndependent)
+
 glslang_pch(MachineIndependent MachineIndependent/pch.h)
 
 target_link_libraries(MachineIndependent PRIVATE OGLCompiler OSDependent GenericCodeGen)
@@ -156,18 +159,22 @@ set(GLSLANG_HEADERS
     Include/intermediate.h
     Include/PoolAlloc.h
     Include/ResourceLimits.h
-    Include/revision.h
     Include/ShHandle.h
     Include/Types.h)
 
 add_library(glslang ${LIB_TYPE} ${BISON_GLSLParser_OUTPUT_SOURCE} ${GLSLANG_SOURCES} ${GLSLANG_HEADERS})
-set_property(TARGET glslang PROPERTY FOLDER glslang)
-set_property(TARGET glslang PROPERTY POSITION_INDEPENDENT_CODE ON)
+set_target_properties(glslang PROPERTIES
+    FOLDER glslang
+    POSITION_INDEPENDENT_CODE ON
+    VERSION   "${GLSLANG_VERSION}"
+    SOVERSION "${GLSLANG_VERSION_MAJOR}")
 target_link_libraries(glslang PRIVATE OGLCompiler OSDependent MachineIndependent)
 target_include_directories(glslang PUBLIC
     $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/..>
     $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
 
+glslang_add_build_info_dependency(glslang)
+
 glslang_only_export_explicit_symbols(glslang)
 
 if(WIN32 AND BUILD_SHARED_LIBS)
@@ -213,4 +220,7 @@ if(ENABLE_GLSLANG_INSTALL)
         get_filename_component(dir ${file} DIRECTORY)
         install(FILES ${file} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/glslang/${dir})
     endforeach()
+
+    install(FILES ${GLSLANG_BUILD_INFO_H} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/glslang)
+
 endif(ENABLE_GLSLANG_INSTALL)

glslang/Include/revision.h

@@ -1,3 +0,0 @@
-// This header is generated by the make-revision script.
-
-#define GLSLANG_PATCH_LEVEL 3847

glslang/Include/revision.template

@@ -1,13 +0,0 @@
-// The file revision.h should be updated to the latest version, somehow, on
-// check-in, if glslang has changed.
-//
-// revision.template is the source for revision.h when using SubWCRev as the
-// method of updating revision.h.  You don't have to do it this way, the
-// requirement is only that revision.h gets updated.
-//
-// revision.h is under source control so that not all consumers of glslang
-// source have to figure out how to create revision.h just to get a build
-// going.  However, if it is not updated, it can be a version behind.
-
-#define GLSLANG_REVISION "$WCREV$"
-#define GLSLANG_DATE     "$WCDATE$"

glslang/MachineIndependent/ShaderLang.cpp

@@ -72,6 +72,9 @@
 // token to print ", but none of that seems appropriate for this file.
 #include "preprocessor/PpTokens.h"
 
+// Build-time generated includes
+#include "glslang/build_info.h"
+
 namespace { // anonymous namespace for file-local functions and symbols
 
 // Total number of successful initializers of glslang: a refcount
@@ -1684,19 +1687,29 @@ int ShGetUniformLocation(const ShHandle handle, const char* name)
 
 namespace glslang {
 
-#include "../Include/revision.h"
+Version GetVersion()
+{
+    Version version;
+    version.major = GLSLANG_VERSION_MAJOR;
+    version.minor = GLSLANG_VERSION_MINOR;
+    version.patch = GLSLANG_VERSION_PATCH;
+    version.flavor = GLSLANG_VERSION_FLAVOR;
+    return version;
+}
 
 #define QUOTE(s) #s
 #define STR(n) QUOTE(n)
 
 const char* GetEsslVersionString()
 {
-    return "OpenGL ES GLSL 3.20 glslang Khronos. " STR(GLSLANG_MINOR_VERSION) "." STR(GLSLANG_PATCH_LEVEL);
+    return "OpenGL ES GLSL 3.20 glslang Khronos. " STR(GLSLANG_VERSION_MAJOR) "." STR(GLSLANG_VERSION_MINOR) "." STR(
+        GLSLANG_VERSION_PATCH) GLSLANG_VERSION_FLAVOR;
 }
 
 const char* GetGlslVersionString()
 {
-    return "4.60 glslang Khronos. " STR(GLSLANG_MINOR_VERSION) "." STR(GLSLANG_PATCH_LEVEL);
+    return "4.60 glslang Khronos. " STR(GLSLANG_VERSION_MAJOR) "." STR(GLSLANG_VERSION_MINOR) "." STR(
+        GLSLANG_VERSION_PATCH) GLSLANG_VERSION_FLAVOR;
 }
 
 int GetKhronosToolId()

glslang/Public/ShaderLang.h

@@ -74,11 +74,6 @@
     extern "C" {
 #endif
 
-// This should always increase, as some paths to do not consume
-// a more major number.
-// It should increment by one when new functionality is added.
-#define GLSLANG_MINOR_VERSION 15
-
 //
 // Call before doing any other compiler/linker operations.
 //
@@ -399,6 +394,14 @@ class TInfoSink;
 
 namespace glslang {
 
+struct Version {
+    int major;
+    int minor;
+    int patch;
+    const char* flavor;
+};
+
+GLSLANG_EXPORT Version GetVersion();
 GLSLANG_EXPORT const char* GetEsslVersionString();
 GLSLANG_EXPORT const char* GetGlslVersionString();
 GLSLANG_EXPORT int GetKhronosToolId();

make-revision

@@ -1,6 +0,0 @@
-#!/bin/sh
-(
-echo "// This header is generated by the make-revision script."
-echo
-echo \#define GLSLANG_PATCH_LEVEL `git log --oneline | wc -l`
-) > glslang/Include/revision.h