glsl: Allow compatibility shaders with MESA_GL_VERSION_OVERRIDE=...

Previously if you used MESA_GL_VERSION_OVERRIDE=3.3COMPAT, Mesa exposed
an OpenGL 3.3 compatibility profile context (with various unimplemented
features and bugs), but still refused to compile shaders with

   #version 330 compatibility

This patch simply adds a small bit of plumbing to let that through.

Of course the same caveats apply: compatibility profile is still not
supported (and will not be supported), so there are no guarantees that
anything will work.

Tested-by: Dylan Baker <dylan@pnwbakers.com>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

src/compiler/glsl/builtin_types.cpp

@@ -288,7 +288,7 @@ _mesa_glsl_initialize_types(struct _mesa_glsl_parse_state *state)
    /* Add deprecated structure types.  While these were deprecated in 1.30,
     * they're still present.  We've removed them in 1.40+ (OpenGL 3.1+).
     */
-   if (!state->es_shader && state->language_version < 140) {
+   if (state->compat_shader) {
       for (unsigned i = 0; i < ARRAY_SIZE(deprecated_types); i++) {
          add_type(symbols, deprecated_types[i]);
       }

src/compiler/glsl/builtin_variables.cpp

@@ -444,7 +444,7 @@ private:
 builtin_variable_generator::builtin_variable_generator(
    exec_list *instructions, struct _mesa_glsl_parse_state *state)
    : instructions(instructions), state(state), symtab(state->symbols),
-     compatibility(!state->is_version(140, 100)),
+     compatibility(state->compat_shader || !state->is_version(140, 100)),
      bool_t(glsl_type::bool_type), int_t(glsl_type::int_type),
      uint_t(glsl_type::uint_type),
      float_t(glsl_type::float_type), vec2_t(glsl_type::vec2_type),

src/compiler/glsl/glsl_parser_extras.cpp

@@ -83,6 +83,7 @@ _mesa_glsl_parse_state::_mesa_glsl_parse_state(struct gl_context *_ctx,
    this->forced_language_version = ctx->Const.ForceGLSLVersion;
    this->zero_init = ctx->Const.GLSLZeroInit;
    this->gl_version = 20;
+   this->compat_shader = true;
    this->es_shader = false;
    this->ARB_texture_rectangle_enable = true;
 
@@ -370,6 +371,7 @@ _mesa_glsl_parse_state::process_version_directive(YYLTYPE *locp, int version,
                                                   const char *ident)
 {
    bool es_token_present = false;
+   bool compat_token_present = false;
    if (ident) {
       if (strcmp(ident, "es") == 0) {
          es_token_present = true;
@@ -379,8 +381,12 @@ _mesa_glsl_parse_state::process_version_directive(YYLTYPE *locp, int version,
              * a core profile shader since that's the only profile we support.
              */
          } else if (strcmp(ident, "compatibility") == 0) {
-            _mesa_glsl_error(locp, this,
+            compat_token_present = true;
-                             "the compatibility profile is not supported");
+
+            if (this->ctx->API != API_OPENGL_COMPAT) {
+               _mesa_glsl_error(locp, this,
+                                "the compatibility profile is not supported");
+            }
          } else {
             _mesa_glsl_error(locp, this,
                              "\"%s\" is not a valid shading language profile; "
@@ -412,6 +418,9 @@ _mesa_glsl_parse_state::process_version_directive(YYLTYPE *locp, int version,
    else
       this->language_version = version;
 
+   this->compat_shader = compat_token_present ||
+                         (!this->es_shader && this->language_version < 140);
+
    bool supported = false;
    for (unsigned i = 0; i < this->num_supported_versions; i++) {
       if (this->supported_versions[i].ver == this->language_version

src/compiler/glsl/glsl_parser_extras.h

@@ -348,6 +348,7 @@ struct _mesa_glsl_parse_state {
    } supported_versions[16];
 
    bool es_shader;
+   bool compat_shader;
    unsigned language_version;
    unsigned forced_language_version;
    bool zero_init;