Check g++ version compatibility (#2044)

* #include an absolute path didn't work - because paths were taken to always be relative.

* Test gcc >= 5.0

* Disable codegen for reflection tests.

* Add parsing options.

* Small comment changes to kick CI build.

3 files changed, 32 insertions, 3 deletions

diff --git a/source/compiler-core/slang-gcc-compiler-util.cpp b/source/compiler-core/slang-gcc-compiler-util.cpp
index 5d72e675a..b5c359247 100644
--- a/source/compiler-core/slang-gcc-compiler-util.cpp
+++ b/source/compiler-core/slang-gcc-compiler-util.cpp
@@ -205,7 +205,9 @@ static SlangResult _parseGCCFamilyLine(const UnownedStringSlice& line, LineParse
         #include "../slang.h"
         ^~~~~~~~~~~~
         compilation terminated.*/
-    
+
+    /* g++: error: unrecognized command line option ‘-std=c++14’ */
+
     outDiagnostic.stage = Diagnostic::Stage::Compile;
 
     List<UnownedStringSlice> split;
@@ -257,7 +259,9 @@ static SlangResult _parseGCCFamilyLine(const UnownedStringSlice& line, LineParse
 
         // Check for special handling for clang (Can be Clang or clang apparently)
         if (split0.startsWith(UnownedStringSlice::fromLiteral("clang")) ||
-            split0.startsWith(UnownedStringSlice::fromLiteral("Clang")) )
+            split0.startsWith(UnownedStringSlice::fromLiteral("Clang")) ||
+            split0 == UnownedStringSlice::fromLiteral("g++") ||
+            split0 == UnownedStringSlice::fromLiteral("gcc"))
         {
             // Extract the type
             SLANG_RETURN_ON_FAIL(_parseSeverity(split[1].trim(), outDiagnostic.severity));
@@ -654,6 +658,22 @@ static SlangResult _parseGCCFamilyLine(const UnownedStringSlice& line, LineParse
     RefPtr<DownstreamCompiler> compiler;
     if (SLANG_SUCCEEDED(createCompiler(ExecutableLocation(path, "g++"), compiler)))
     {
+        // A downstream compiler for Slang must currently support C++14 - such that
+        // the prelude and generated code works.
+        // 
+        // The first version of gcc that supports `-std=c++14` is 5.0
+        // https://gcc.gnu.org/projects/cxx-status.html
+        //
+        // If could be argued to allow C/C++ compilations via older versions through an older version
+        // but that requires some more complex behavior, so we don't allow for now.
+        
+        auto desc = compiler->getDesc();
+        if (desc.majorVersion < 5)
+        {
+            // If the version isn't 5 or higher, we don't add this version of the compiler.
+            return SLANG_OK;
+        }
+
         set->addCompiler(compiler);
     }
     return SLANG_OK;
diff --git a/tools/slang-reflection-test/slang-reflection-test-main.cpp b/tools/slang-reflection-test/slang-reflection-test-main.cpp
index 0b8e88d68..af6da5113 100644
--- a/tools/slang-reflection-test/slang-reflection-test-main.cpp
+++ b/tools/slang-reflection-test/slang-reflection-test-main.cpp
@@ -1285,6 +1285,15 @@ static SlangResult maybeDumpDiagnostic(SlangResult res, SlangCompileRequest* req
 
 SlangResult performCompilationAndReflection(SlangCompileRequest* request, int argc, const char*const* argv)
 {
+    // We don't actually need codegen to get reflection.
+    // 
+    // Ideally perhaps this would use a call to
+    // request->setCompileFlags(flags);
+    // But that relies on knowing what flags are set, and there isn't a way to get that, so do it arg way
+
+    const char* noCodeGenArgs[] = { "-no-codegen" };
+    SLANG_RETURN_ON_FAIL(maybeDumpDiagnostic(spProcessCommandLineArguments(request, noCodeGenArgs, SLANG_COUNT_OF(noCodeGenArgs)), request));
+
     SLANG_RETURN_ON_FAIL(maybeDumpDiagnostic(spProcessCommandLineArguments(request, &argv[1], argc - 1), request));
     SLANG_RETURN_ON_FAIL(maybeDumpDiagnostic(spCompile(request), request));
 
diff --git a/tools/slang-test/slang-test-main.cpp b/tools/slang-test/slang-test-main.cpp
index f57fe22a1..685e9dd7a 100644
--- a/tools/slang-test/slang-test-main.cpp
+++ b/tools/slang-test/slang-test-main.cpp
@@ -1914,7 +1914,7 @@ static TestResult runCPPCompilerExecute(TestContext* context, TestInput& input)
 
     const auto& diagnostics = compileResult->getDiagnostics();
 
-    // If the actual compilation failed, then the output will be
+    // If the actual compilation failed, then the output will be the summary
     if (SLANG_FAILED(diagnostics.result))
     {
         actualOutput = _calcSummary(diagnostics);