Support for getting git version from IGlobalSession (#1040)

* Added slang-tag-version.h and travis code to generate the file.

* Generate slang-tag-version.h on appveyor.

* Move where slang-tag-version.h is generated on appveyor.

* Dump slang-tag-version.h to console on travis.

* Cat slang-tag-version.h

* Added method getBuildTagVersion to IGlobalSession.
Added -v option.

9 files changed, 33 insertions, 2 deletions

diff --git a/.travis.yml b/.travis.yml
index 15f630776..b613fdbfb 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -46,7 +46,7 @@ before_deploy: |
   export SLANG_ARCH_NAME=`uname -p`
   export SLANG_TAG=${TRAVIS_TAG#v}
   export SLANG_BINARY_ARCHIVE=slang-${SLANG_TAG}-${SLANG_OS_NAME}-${SLANG_ARCH_NAME}.zip
-  zip -r ${SLANG_BINARY_ARCHIVE} bin/*/*/slangc bin/*/*/libslang.so bin/*/*/libslang-glslang.so docs/*.md README.md LICENSE slang.h slang-com-helper.h slang-com-ptr.h prelude/*.h
+  zip -r ${SLANG_BINARY_ARCHIVE} bin/*/*/slangc bin/*/*/libslang.so bin/*/*/libslang-glslang.so docs/*.md README.md LICENSE slang.h slang-com-helper.h slang-com-ptr.h slang-tag-version.h prelude/*.h
 
 # We are going to deploy to GitHub Releases
 # on a successful build from a tag, but only
diff --git a/appveyor.yml b/appveyor.yml
index 91dce1671..7a0e194a2 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -12,11 +12,12 @@ init:
       {
         $env:SLANG_VERSION = "dev-$($env:APPVEYOR_REPO_COMMIT.Substring(0, 7))"
       }
-
+      
 # The project uses a submodule for the "glslang" dependency,
 # so we need to make sure to pull that before building.
 install:
   - git submodule update --init --recursive
+  - ps: git describe --tags | %{$_ -replace "^", "#define SLANG_TAG_VERSION """ -replace "$", """"} > slang-tag-version.h 
 
 # We want to build the full matrix of platforms and configurations
 # that we support on Windows.
@@ -85,6 +86,7 @@ after_build:
       7z a "$env:SLANG_BINARY_ARCHIVE" slang.h
       7z a "$env:SLANG_BINARY_ARCHIVE" slang-com-helper.h
       7z a "$env:SLANG_BINARY_ARCHIVE" slang-com-ptr.h
+      7z a "$env:SLANG_BINARY_ARCHIVE" slang-tag-version.h
       7z a "$env:SLANG_BINARY_ARCHIVE" prelude\*.h
       7z a "$env:SLANG_BINARY_ARCHIVE" bin\*\*\slang.dll
       7z a "$env:SLANG_BINARY_ARCHIVE" bin\*\*\slang.lib
@@ -97,6 +99,7 @@ after_build:
       7z a "$env:SLANG_SOURCE_ARCHIVE" slang.h
       7z a "$env:SLANG_SOURCE_ARCHIVE" slang-com-helper.h
       7z a "$env:SLANG_SOURCE_ARCHIVE" slang-com-ptr.h
+      7z a "$env:SLANG_SOURCE_ARCHIVE" slang-tag-version.h
       7z a "$env:SLANG_SOURCE_ARCHIVE" prelude\*.h
       7z a "$env:SLANG_SOURCE_ARCHIVE" source\*\*.h
       7z a "$env:SLANG_SOURCE_ARCHIVE" source\*\*.cpp
diff --git a/docs/command-line-slangc.md b/docs/command-line-slangc.md
index 65ac7411b..233656057 100644
--- a/docs/command-line-slangc.md
+++ b/docs/command-line-slangc.md
@@ -80,6 +80,8 @@ Options
 
 For completeness, here are the options that `slangc` currently accepts:
 
+* `-v`: Displays the build version. This is the contents of `git describe --tags`. It is typically only set from automated builds (such as distros available on github). A user build will by default be 'unknown'. 
+
 * `-D <name>[=<value>]`: Insert a preprocessor macro definition
   * The space between `-D` and `<name>` is optional
   * If no `<value>` is specified, Slang will define the macro with an empty value
diff --git a/slang-tag-version.h b/slang-tag-version.h
new file mode 100644
index 000000000..f2ecc1d4f
--- /dev/null
+++ b/slang-tag-version.h
@@ -0,0 +1 @@
+#define SLANG_TAG_VERSION "unknown"
diff --git a/slang.h b/slang.h
index 6a6ddd0d0..4d775ac45 100644
--- a/slang.h
+++ b/slang.h
@@ -2669,6 +2669,15 @@ namespace slang
         virtual SLANG_NO_THROW void SLANG_MCALL setDownstreamCompilerPrelude(
             SlangPassThrough passThrough,
             const char* preludeText) = 0;
+
+            /** Get the build version 'tag' string. The string is the same as produced via `git describe --tags`
+            for the project. If Slang is built separately from the automated build scripts
+            the contents will by default be 'unknown'. Any string can be set by changing the
+            contents of 'slang-tag-version.h' file and recompiling the project.
+
+            @return The build tag string
+            */
+        virtual SLANG_NO_THROW const char* SLANG_MCALL getBuildTagString() = 0;
     };
 
     #define SLANG_UUID_IGlobalSession { 0xc140b5fd, 0xc78, 0x452e, { 0xba, 0x7c, 0x1a, 0x1e, 0x70, 0xc7, 0xf7, 0x1c } };
diff --git a/source/slang/slang-compiler.h b/source/slang/slang-compiler.h
index a6be59c76..0b97e2af7 100644
--- a/source/slang/slang-compiler.h
+++ b/source/slang/slang-compiler.h
@@ -1807,6 +1807,8 @@ namespace Slang
             SlangPassThrough inPassThrough,
             char const* prelude) override;
 
+        SLANG_NO_THROW const char* SLANG_MCALL getBuildTagString() override;
+
         enum class SharedLibraryFuncType
         {
             Glslang_Compile,
diff --git a/source/slang/slang-options.cpp b/source/slang/slang-options.cpp
index a55322d31..94f82ef31 100644
--- a/source/slang/slang-options.cpp
+++ b/source/slang/slang-options.cpp
@@ -800,6 +800,10 @@ struct OptionsParser
                         return SLANG_FAIL;
                     }
                 }
+                else if (argStr == "-v")
+                {
+                    sink->diagnoseRaw(Severity::Note, session->getBuildTagString());
+                }
                 else if (argStr == "--")
                 {
                     // The `--` option causes us to stop trying to parse options,
diff --git a/source/slang/slang.cpp b/source/slang/slang.cpp
index 601312def..da04587fd 100644
--- a/source/slang/slang.cpp
+++ b/source/slang/slang.cpp
@@ -1,4 +1,5 @@
 #include "../../slang.h"
+#include "../../slang-tag-version.h"
 
 #include "../core/slang-io.h"
 #include "../core/slang-string-util.h"
@@ -201,6 +202,11 @@ SLANG_NO_THROW void SLANG_MCALL Session::setDownstreamCompilerPrelude(
     m_downstreamCompilerPreludes[int(passThrough)] = prelude;
 }
 
+SLANG_NO_THROW const char* SLANG_MCALL Session::getBuildTagString()
+{
+    return SLANG_TAG_VERSION;
+}
+
 struct IncludeHandlerImpl : IncludeHandler
 {
     Linkage*    linkage;
diff --git a/travis_build.sh b/travis_build.sh
index d25958906..82ac8788b 100644
--- a/travis_build.sh
+++ b/travis_build.sh
@@ -4,6 +4,10 @@
 wget https://github.com/shader-slang/slang-binaries/blob/master/premake/premake-5.0.0-alpha13/bin/linux-64/premake5?raw=true -O premake5
 chmod u+x premake5
 
+# generate slang-tag-version.h 
+git describe --tags | sed -e "s/\(.*\)/\#define SLANG_TAG_VERSION \"\1\"/" > slang-tag-version.h
+cat slang-tag-version.h 
+ 
 # Create the makefile
 ./premake5 gmake --cc=${CC}