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At least in the web development world we have sourcemaps for that, html/css/js can all be inspected and debugged in their original form. Is there anything like

At least in the web development world we have sourcemaps for that, html/css/js can all be inspected and debugged in their original form. Is there anything like this for C?

kccqzy 8y ago
Meanwhile I find it troublesome to rely on source maps even in web development. The JavaScript ecosystem doesn't produce nice enough abstractions that you can totally forget about the generated code and work in the original code. Just read the generated JavaScript actually run by browsers. Debugging sometimes really requires cutting through abstractions.
- weberc2 8y ago
  Same here. I did a bit of CoffeeScript development and source maps rarely worked properly. Arguably we just didn't have them set up properly, but it's a condemnation in its own right if our smarter-than-average engineers can't configure the technology properly.
Gibbon1 8y ago
I don't do web dev but you can debug mixed source and assembly. You can switch back and forth between stepping though source or assemble and inspect registers and variables at the same time. It starts to break down with heavily optimized code. Part of the reason C still exists is enormous amounts of work went into the tooling.
blattimwind 8y ago
Probably the majority of generated C code is where the input language lives in an entirely different domain (e.g. parsers), so sourcemaps wouldn't help.
xemdetia 8y ago
I haven't used sourcemaps enough to know for sure that the following problem isn't accommodated for: It's sometimes extremely opaque that you finally hit something arbitrary like an int32/uint32 mismatch or situations where you are dealing with a second class language to normal getting an interface and running into some weird quirk of how the interpreter passes data into the FFI. There is also the other potential issue that the final code is doing something strange because of some #define magic, which is also very hard to trace without being able to walk through code.
flukus 8y ago
I'm not sure if it's standard c/c++ but there are the #line directives (https://gcc.gnu.org/onlinedocs/cpp/Line-Control.html https://gcc.gnu.org/onlinedocs/cpp/Line-Control.html), bison and flex use them to good effect and I've used them when piping code into gcc. It'll give compiler errors in the right places and make gdb behave when stepping through code, not sure if it runs into limitations or not. According to the oldest docs I could quickly find (https://gcc.gnu.org/onlinedocs/gcc-4.0.4/cpp/Line-Control.html https://gcc.gnu.org/onlinedocs/gcc-4.0.4/cpp/Line-Control.ht...) it goes back to at least gcc 2.95 in 1999, but I wouldn't be surprised if it predated javascript and css themselves.
UncleEntity 8y ago
> Is there anything like this for C? I've been fixing up some ~15 year old code to compilable state and the flex/bison bugs were showing up with the flex/bison line numbers where the errors originated -- which somewhat helps but it turned out none of the errors were actually from flex/bison but because of how their API changed over the years. I'd get some WTF compilers errors and track them down to running the output of flex through sed in a perl script to do something that it now does out of the box and didn't like being messed with, fun times...well, it actually is fun times since I'm just doing this on my own so I can play with the software.
Mikhail_Edoshin 8y ago
C preprocessor supports the `#line` directive that can specify a custom source file/line combination. The compiler (or the runtime code with `__FILE__` and `__LINE__` macros) can then use it to report the location of the error.

At least in the web development world we have sourcemaps for that, html/css/js can all be inspected and debugged in their original form. Is there anything like this for C?

kccqzy 8y ago

Meanwhile I find it troublesome to rely on source maps even in web development. The JavaScript ecosystem doesn't produce nice enough abstractions that you can totally forget about the generated code and work in the original code. Just read the generated JavaScript actually run by browsers. Debugging sometimes really requires cutting through abstractions.

weberc2 8y ago
Same here. I did a bit of CoffeeScript development and source maps rarely worked properly. Arguably we just didn't have them set up properly, but it's a condemnation in its own right if our smarter-than-average engineers can't configure the technology properly.

Gibbon1 8y ago

I don't do web dev but you can debug mixed source and assembly. You can switch back and forth between stepping though source or assemble and inspect registers and variables at the same time. It starts to break down with heavily optimized code. Part of the reason C still exists is enormous amounts of work went into the tooling.

blattimwind 8y ago

Probably the majority of generated C code is where the input language lives in an entirely different domain (e.g. parsers), so sourcemaps wouldn't help.

xemdetia 8y ago

I haven't used sourcemaps enough to know for sure that the following problem isn't accommodated for: It's sometimes extremely opaque that you finally hit something arbitrary like an int32/uint32 mismatch or situations where you are dealing with a second class language to normal getting an interface and running into some weird quirk of how the interpreter passes data into the FFI. There is also the other potential issue that the final code is doing something strange because of some #define magic, which is also very hard to trace without being able to walk through code.

flukus 8y ago

I'm not sure if it's standard c/c++ but there are the #line directives (https://gcc.gnu.org/onlinedocs/cpp/Line-Control.html https://gcc.gnu.org/onlinedocs/cpp/Line-Control.html), bison and flex use them to good effect and I've used them when piping code into gcc. It'll give compiler errors in the right places and make gdb behave when stepping through code, not sure if it runs into limitations or not. According to the oldest docs I could quickly find (https://gcc.gnu.org/onlinedocs/gcc-4.0.4/cpp/Line-Control.html https://gcc.gnu.org/onlinedocs/gcc-4.0.4/cpp/Line-Control.ht...) it goes back to at least gcc 2.95 in 1999, but I wouldn't be surprised if it predated javascript and css themselves.

UncleEntity 8y ago

> Is there anything like this for C? I've been fixing up some ~15 year old code to compilable state and the flex/bison bugs were showing up with the flex/bison line numbers where the errors originated -- which somewhat helps but it turned out none of the errors were actually from flex/bison but because of how their API changed over the years. I'd get some WTF compilers errors and track them down to running the output of flex through sed in a perl script to do something that it now does out of the box and didn't like being messed with, fun times...well, it actually is fun times since I'm just doing this on my own so I can play with the software.

Mikhail_Edoshin 8y ago

C preprocessor supports the `#line` directive that can specify a custom source file/line combination. The compiler (or the runtime code with `__FILE__` and `__LINE__` macros) can then use it to report the location of the error.