RFC: introduce check macro that can be disabled with a flag

base/exports.jl

@@ -1168,6 +1168,7 @@ export
     @polly,
 
     @assert,
+    @check,
     @__dot__,
     @enum,
     @label,

base/options.jl

@@ -21,6 +21,7 @@ struct JLOptions
     opt_level::Int8
     debug_level::Int8
     check_bounds::Int8
+    julia_debug::Int8
     depwarn::Int8
     warn_overwrite::Int8
     can_inline::Int8

base/pkg/pkg.jl

@@ -86,7 +86,7 @@ init(meta::AbstractString=DEFAULT_META, branch::AbstractString=META_BRANCH) = Di
 
 function __init__()
     vers = "v$(VERSION.major).$(VERSION.minor)"
-    pushfirst!(Base.LOAD_CACHE_PATH, abspath(Dir._pkgroot(), "lib", vers))
+    pushfirst!(Base.LOAD_CACHE_PATH, abspath(Dir._pkgroot(), "lib", Base.JLOptions().julia_debug == 1 ? "debug" : ""), vers)
 end
 
 """

base/sysimg.jl

@@ -501,6 +501,14 @@ function __init__()
     init_threadcall()
 end
 
+macro check(x)
+    if JLOptions().julia_debug == 1
+        return :($(esc(x)))
+    else
+        return nothing
+    end
+end
+
 INCLUDE_STATE = 3 # include = include_relative
 
 end # baremodule Base

doc/man/julia.1

@@ -151,6 +151,10 @@ Control whether inlining is permitted (overrides functions declared as @inline)
 --check-bounds={yes|no}
 Emit bounds checks always or never (ignoring declarations)
 
+.TP
+--debug={yes|no}
+Enable the @check macro and always emit bounds checks
+
 .TP
 --math-mode={ieee|user}
 Always use IEEE semantics for math (ignoring declarations),

src/jloptions.c

@@ -50,6 +50,11 @@ jl_options_t jl_options = { 0,    // quiet
                             1,    // debug_level [release build]
 #endif
                             JL_OPTIONS_CHECK_BOUNDS_DEFAULT, // check_bounds
+#ifdef JL_DEBUG_BUILD
+                            1, // julia debug mode [debug build]
+#else
+                            0, // julia debug mode [release build]
+#endif
                             JL_OPTIONS_DEPWARN_ON,    // deprecation warning
                             0,    // method overwrite warning
                             1,    // can_inline
@@ -118,6 +123,7 @@ static const char opts[]  =
 #endif
     " --inline={yes|no}         Control whether inlining is permitted, including overriding @inline declarations\n"
     " --check-bounds={yes|no}   Emit bounds checks always or never (ignoring declarations)\n"
+    " --debug={yes|no}          Enable the @check macro and always emit bounds checks\n"
 #ifdef USE_POLLY
     " --polly={yes|no}          Enable or disable the polyhedral optimizer Polly (overrides @polly declaration)\n"
 #endif
@@ -151,6 +157,7 @@ JL_DLLEXPORT void jl_parse_opts(int *argcp, char ***argvp)
            opt_code_coverage,
            opt_track_allocation,
            opt_check_bounds,
+           opt_julia_debug,
            opt_output_jit_bc,
            opt_output_unopt_bc,
            opt_output_bc,
@@ -200,6 +207,7 @@ JL_DLLEXPORT void jl_parse_opts(int *argcp, char ***argvp)
         { "track-allocation",optional_argument, 0, opt_track_allocation },
         { "optimize",        optional_argument, 0, 'O' },
         { "check-bounds",    required_argument, 0, opt_check_bounds },
+        { "debug",           required_argument, 0, opt_julia_debug },
         { "output-bc",       required_argument, 0, opt_output_bc },
         { "output-unopt-bc", required_argument, 0, opt_output_unopt_bc },
         { "output-jit-bc",   required_argument, 0, opt_output_jit_bc },
@@ -489,6 +497,16 @@ JL_DLLEXPORT void jl_parse_opts(int *argcp, char ***argvp)
             else
                 jl_errorf("julia: invalid argument to --check-bounds={yes|no} (%s)", optarg);
             break;
+        case opt_julia_debug:
+            if (!strcmp(optarg,"yes")) {
+                jl_options.check_bounds = 1;
+                jl_options.check_bounds = JL_OPTIONS_CHECK_BOUNDS_ON;
+            }
+            else if (!strcmp(optarg,"no"))
+                jl_options.check_bounds = 0;
+            else
+                jl_errorf("julia: invalid argument to --debug={yes|no} (%s)", optarg);
+            break;
         case opt_output_bc:
             jl_options.outputbc = optarg;
             if (!jl_options.image_file_specified) jl_options.image_file = NULL;

src/julia.h

@@ -1716,6 +1716,7 @@ typedef struct {
     int8_t malloc_log;
     int8_t opt_level;
     int8_t debug_level;
+    int8_t julia_debug;
     int8_t check_bounds;
     int8_t depwarn;
     int8_t warn_overwrite;