Matthew Cole colematt

Fix ‘numeric_limits’ is not a member of ‘std’ error in LLVM 10.0

This problem has been verified in both of the LLVM 10.0.0 and 10.0.1 releases' monorepos. The problem and fix is shown for 10.0.1, but the patch can be applied to a 10.0.0 monorepo.

Problem

[3273/3351] Building CXX object utils/.../benchmark.dir/benchmark_register.cc.o
FAILED: utils/benchmark/src/CMakeFiles/benchmark.dir/benchmark_register.cc.o 
/usr/bin/c++ -DHAVE_POSIX_REGEX -DHAVE_STD_REGEX -DHAVE_STEADY_CLOCK -D_DEBUG -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Dbenchmark_EXPORTS -I/home/matthew/llvm-project-10.0.1/build/utils/benchmark/src -I/home/matthew/llvm-project-10.0.1/llvm/utils/benchmark/src -I/usr/include/libxml2 -I/home/matthew/llvm-project-10.0.1/build/include -I/home/matthew/llvm-project-10.0.1/llvm/include -I/home/matthew/llvm-project-10.0.1/llvm/utils/benchmark/include -I/home/matthew/llvm-project-10.0.1/llvm/utils/benchmark/src/../include -fPIC -fvisibility-inlines-hidden

Connecting to Remote by SSH

Virtual Private Network (VPN)
- Windows
- MacOS
- Linux
Secure Shell (SSH) Client
- Windows

How to generate an LLVM docset for Dash

Prerequisites

brew install swiftdocorg/formulae/docsetutil
sudo ln -s /usr/local/bin/docsetutil /Library/Developer/CommandLineTools/usr/bin/docsetutil
brew install doxygen graphviz

export PROJ_ROOT=$(pwd)
mkdir -p llvm && cd llvm

# Using Ubuntu 18.04 Prebuild Toolchain from https://releases.llvm.org/download.html
wget https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.0/clang+llvm-10.0.0-x86_64-linux-gnu-ubuntu-18.04.tar.xz \
     https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.0/clang+llvm-10.0.0-x86_64-linux-gnu-ubuntu-18.04.tar.xz.sig \
     https://releases.llvm.org/10.0.0/hans-gpg-key.asc
gpg --import hans-gpg-key.asc
gpg --verify clang+llvm-10.0.0-x86_64-linux-gnu-ubuntu-18.04.tar.xz.sig clang+llvm-10.0.0-x86_64-linux-gnu-ubuntu-18.04.tar.xz

Array Recipes

Get elements from a multi-dimensional array

import functools
import operator
import typing
def arrget(arr:typing.Sequence,pos:tuple[int,...]) -> typing.Any:
 """

Allocating Multi-dimensional Arrays in C

This gist was inspired by the Geeks for Geeks' writeup How to dynamically allocate a 2D array in C? by Abhay Rathi. It has been formatted to remove interstitial ads, provide a fixed URL for links, and to modify the problem statement to match that which is commonly used in Hackerrank/Grind75/LeetCode/ACM problems where the input must be read from standard input.

Problem

We want to read input from standard input, where the nature of the input is as follows:

On line 1, $R$: the number of rows, and $C$: the number of columns in a 2D array, space-separated and newline-terminated.
On lines 2 through $R+1$, the row's columns, space-separated and newline-terminated.

Where does the C/C++ Compiler Find Header Files?

Ask the Preprocessor

GNU

# GNU C++ preprocessor
`gcc -print-prog-name=cc1plus` -v
# GNU C preprocessor

	#include <locale.h>
	#include <stdio.h>
	#include <wchar.h>

	/* REFERENCES
	* Control Block: http://unicode.org/charts/PDF/U0000.pdf
	* Control Pictures: http://unicode.org/charts/PDF/U2400.pdf
	*/

	int main(int argc, char* argv[]) {

	CFLAGS=-g -Wall -std=c99
	LDFLAGS=
	LDLIBS=-lcunit
	RMFLAGS=-f

	all: basic

	.PHONY: clean
	clean:
	$(RM) $(RMFLAGS) basic

	#include <stdint.h> // uint64_t
	#include <stdio.h> // printf

	uint64_t twiddle(uint64_t x) {
	uint64_t smallest, ripple, new_smallest, ones;

	if (x == 0)
	return 0;
	smallest = (x & -x);
	ripple = x + smallest;