gl backend: Add line numbers to source in glsl compilation errors

Almost always the source is created by combining various sources, which
means the line numbers in the error messages are hard to use. Adding
the line numbers to the source in the error message helps with this.

diff --git a/gsk/gl/gskglshaderbuilder.c b/gsk/gl/gskglshaderbuilder.c
index 66f0a3843e88f0638598ca7ffb458c66f8374445..443048865e6cc6a28e14d2187b66fc8ca744712d 100644 (file)
--- a/gsk/gl/gskglshaderbuilder.c
+++ b/gsk/gl/gskglshaderbuilder.c
@@ -47,7 +47,9 @@ check_shader_error (int     shader_id,
   int log_len;
   char *buffer;
   int code_len;
-  char *code;
+  int line;
+  char *code, *p;
+  GString *s;
 
   glGetShaderiv (shader_id, GL_COMPILE_STATUS, &status);
 
@@ -62,11 +64,29 @@ check_shader_error (int     shader_id,
   code = g_malloc0 (code_len + 1);
   glGetShaderSource (shader_id, code_len, NULL, code);
 
+  s = g_string_new ("");
+  p = code;
+  line = 1;
+  while (*p)
+    {
+      char *end = strchr (p, '\n');
+      if (end)
+        end = end + 1; /* Include newline */
+      else
+        end = p + strlen (p);
+
+      g_string_append_printf (s, "%3d| ", line++);
+      g_string_append_len (s, p, end - p);
+
+      p = end;
+    }
+
   g_set_error (error, GDK_GL_ERROR, GDK_GL_ERROR_COMPILATION_FAILED,
                "Compilation failure in shader.\nError message: %s\n\nSource code:\n%s\n\n",
                buffer,
-               code);
+               s->str);
 
+  g_string_free (s, TRUE);
   g_free (buffer);
   g_free (code);