added get_required_extensions() API to GLSL compiler

spirv_cross_c.cpp

@@ -820,6 +820,43 @@ spvc_result spvc_compiler_require_extension(spvc_compiler compiler, const char *
 #endif
 }
 
+size_t spvc_compiler_get_num_required_extensions(spvc_compiler compiler) 
+{
+#if SPIRV_CROSS_C_API_GLSL
+	if (compiler->backend == SPVC_BACKEND_NONE)
+	{
+		compiler->context->report_error("Cross-compilation related option used on NONE backend which only supports reflection.");
+		return SPVC_ERROR_INVALID_ARGUMENT;
+	}
+
+	return static_cast<CompilerGLSL *>(compiler->compiler.get())->get_required_extensions().size();
+#else
+	compiler->context->report_error("Cross-compilation related option used on NONE backend which only supports reflection.");
+	return 0;
+#endif
+}
+
+const char *spvc_compiler_get_required_extension(spvc_compiler compiler, size_t index)
+{
+#if SPIRV_CROSS_C_API_GLSL
+	if (compiler->backend == SPVC_BACKEND_NONE)
+	{
+		compiler->context->report_error("Cross-compilation related option used on NONE backend which only supports reflection.");
+		return nullptr;
+	}
+
+	auto& exts = static_cast<CompilerGLSL *>(compiler->compiler.get())->get_required_extensions();
+	if (index < exts.size()) {
+		return exts[index].c_str();
+	} else {
+		return nullptr;
+	}
+#else
+	compiler->context->report_error("Cross-compilation related option used on NONE backend which only supports reflection.");
+	return nullptr;
+#endif
+}
+
 spvc_result spvc_compiler_flatten_buffer_block(spvc_compiler compiler, spvc_variable_id id)
 {
 #if SPIRV_CROSS_C_API_GLSL

spirv_cross_c.h

@@ -784,6 +784,8 @@ SPVC_PUBLIC_API spvc_result spvc_compiler_compile(spvc_compiler compiler, const
 /* Maps to C++ API. */
 SPVC_PUBLIC_API spvc_result spvc_compiler_add_header_line(spvc_compiler compiler, const char *line);
 SPVC_PUBLIC_API spvc_result spvc_compiler_require_extension(spvc_compiler compiler, const char *ext);
+SPVC_PUBLIC_API size_t spvc_compiler_get_num_required_extensions(spvc_compiler compiler);
+SPVC_PUBLIC_API const char *spvc_compiler_get_required_extension(spvc_compiler compiler, size_t index);
 SPVC_PUBLIC_API spvc_result spvc_compiler_flatten_buffer_block(spvc_compiler compiler, spvc_variable_id id);
 
 SPVC_PUBLIC_API spvc_bool spvc_compiler_variable_is_depth_or_compare(spvc_compiler compiler, spvc_variable_id id);

spirv_glsl.cpp

@@ -15565,6 +15565,10 @@ void CompilerGLSL::require_extension(const std::string &ext)
 		forced_extensions.push_back(ext);
 }
 
+const SmallVector<std::string> &CompilerGLSL::get_required_extensions() const {
+	return forced_extensions;
+}
+
 void CompilerGLSL::require_extension_internal(const string &ext)
 {
 	if (backend.supports_extensions && !has_extension(ext))

spirv_glsl.hpp

@@ -258,6 +258,10 @@ public:
 	// require_extension("GL_KHR_my_extension");
 	void require_extension(const std::string &ext);
 
+	// Returns the list of required extensions. After compilation this will contains any other 
+	// extensions that the compiler used automatically, in addition to the user specified ones.
+	const SmallVector<std::string> &get_required_extensions() const;
+
 	// Legacy GLSL compatibility method.
 	// Takes a uniform or push constant variable and flattens it into a (i|u)vec4 array[N]; array instead.
 	// For this to work, all types in the block must be the same basic type, e.g. mixing vec2 and vec4 is fine, but

tests-other/c_api_test.c

@@ -7,6 +7,7 @@
 #include <spirv_cross_c.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <string.h>
 
 #define SPVC_CHECKED_CALL(x) do { \
 	if ((x) != SPVC_SUCCESS) { \
@@ -175,6 +176,18 @@ int main(int argc, char **argv)
 	SPVC_CHECKED_CALL(spvc_compiler_create_compiler_options(compiler_glsl, &options));
 	SPVC_CHECKED_CALL(spvc_compiler_install_compiler_options(compiler_glsl, options));
 
+	const int NUM_EXTS = 2;
+	const char* expected_exts[NUM_EXTS] = {
+		"EXT_first",
+		"EXT_second"
+	};
+
+	int ext_idx = 0;
+	while(ext_idx < NUM_EXTS) {
+		SPVC_CHECKED_CALL(spvc_compiler_require_extension(compiler_glsl, expected_exts[ext_idx]));
+		ext_idx += 1;
+	}
+
 	SPVC_CHECKED_CALL(spvc_compiler_create_shader_resources(compiler_none, &resources));
 	dump_resources(compiler_none, resources);
 	compile(compiler_glsl, "GLSL");
@@ -183,6 +196,23 @@ int main(int argc, char **argv)
 	compile(compiler_json, "JSON");
 	compile(compiler_cpp, "CPP");
 
+	int num_exts = spvc_compiler_get_num_required_extensions(compiler_glsl);
+	if (num_exts != NUM_EXTS)
+	{
+		fprintf(stderr, "num_exts mismatch!\n");
+		return 1;
+	}
+
+	ext_idx = 0;
+	while(ext_idx < num_exts) {
+		const char* ext = spvc_compiler_get_required_extension(compiler_glsl, ext_idx);
+		if(strcmp(ext, expected_exts[ext_idx]) != 0) {
+			fprintf(stderr, "extension mismatch (%s != %s)!\n", ext, expected_exts[ext_idx]);
+			return 1;
+		}
+		ext_idx += 1;
+	}
+	
 	spvc_context_destroy(context);
 	free(buffer);
 	return 0;