These were defined backwards to the usual convention.
#if GLSLANG_VERSION_GREATER_THAN(11, 10, 0)
This reads as "if glslang version is greater than 11.10.0" to any
reasonable sane programmer, and should therefore expand to
"glslang_version > macro_argument".
Yet the check it references was actually written as "macro_argument >
glslang_version", thus expressing the completely opposite condition of
"if glslang version is *less than* 11.10.0". This is definitely
backwards and extremely, dangerously surprising behavior to any
programmer familiar with such version macros.
I'm not sure if anybody actually ever used them. I certainly didn't, on
account of them being backwards. I could not find a single reference to
them on GitHub (other than in copies of this header) - every project I
found just used the GLSLANG_VERSION_MAJOR etc. macros directly.
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).
