Git prompt using libgit2 (again) (#55)

* Added simple Git repository parsing code

The reference (which can be the branch name or commit hash) is obtained by reading `.git/HEAD` because the suggested way (https://stackoverflow.com/questions/12132862) does not work (`git_repository_head` fails) if there are no commits on the branch yet.

* Workflow: install libgit2 on Linux

* Merge and rebase status

* Cherry-picking and reverting statuses

* Reverted workflow change

* Bisecting status

* Full handling of (unborn) branch name, commit ID and tag

* No need to check if reference is branch

`git_branch_name` already does that

* Status listing with callback

* Moved callback function explanation to declaration

* Replaced state `bool`s with single `std::string`

* Added `bare` member

* Renamed `set_*` methods as `establish_*` because they are not setters

* Skip ignored files in status detection

* Completed status detection code

* Use git information from libgit2 instead of `__git_ps1`

* Updated Bash and Zsh to not pass `__git_ps1` output

* Initialise all primitive members

Use this to detect if there is no Git repository.

* Fixed edge case: a file can be new and modified both

* Removed static linking on Windows

Cannot link libgit2 statically

* Renames and minor fixes

* Moved tag detection to separate method

* Detect annotated and unannotated tags both

* Bit-fiddling to set dirty, staged and untracked statuses

* Removed parameter names from method declarations

* Updated documentation

* Added Windows workflow to build libgit2 statically

* Use Git instead of GitHub CLI, which requires a token

* Install to target

* Fixed `make` command

* Windows has `mkdir`

* Install pkg-onfig

* Removed package workflow

* Removed code to load `__git_ps1` in Bash and Zsh

.bash_aliases

@@ -117,7 +117,7 @@ _after_command()
     local exit_code=$?
     [ -z "${__begin_window+.}" ] && return
     local last_command=$(history 1)
-    PS1=$(custom-bash-prompt "$last_command" $exit_code $__begin_window $COLUMNS "$(__git_ps1 %s)" $SHLVL "$PWD")
+    PS1=$(custom-bash-prompt "$last_command" $exit_code $__begin_window $COLUMNS $SHLVL "$PWD")
     unset __begin_window
 }
 

.bashrc

@@ -114,13 +114,6 @@ then
     _source_one /usr/share/bash-completion/bash_completion /etc/bash_completion
 fi
 
-# Showing the Git branch in the primary prompt depends upon a script which must
-# be sourced separately on some Linux distributions.
-if ! command -v __git_ps1 &>/dev/null
-then
-    _source_one $HOME/Documents/projects/git/contrib/completion/git-prompt.sh /usr/share/git/completion/git-prompt.sh /usr/share/git-core/contrib/completion/git-prompt.sh
-fi
-
 PS1='[\u@\h \w]\$ '
 PS2='──▶ '
 PS3='#? '

.zshrc

@@ -6,7 +6,7 @@ _after_command()
     local exit_code=$?
     [ -z "${__begin_window+.}" ] && return
     local last_command=$(history -n -1 2>/dev/null)
-    PS1=$(custom-zsh-prompt "$last_command" $exit_code $=__begin_window $COLUMNS "$(__git_ps1 %s)" $SHLVL $PWD)
+    PS1=$(custom-zsh-prompt "$last_command" $exit_code $=__begin_window $COLUMNS $SHLVL $PWD)
     unset __begin_window
 }
 
@@ -75,15 +75,6 @@ rr()
     done
 }
 
-if ! command -v __git_ps1 &>/dev/null
-then
-    . ~/Documents/projects/git/contrib/completion/git-prompt.sh &>/dev/null  \
-    || . /usr/lib/git-core/git-sh-prompt &>/dev/null  \
-    || . /usr/share/git-core/contrib/completion/git-prompt.sh &>/dev/null  \
-    || . /usr/share/git/completion/git-prompt.sh &>/dev/null  \
-    || . /usr/share/git/git-prompt.sh &>/dev/null
-fi
-
 ###############################################################################
 # Shell options.
 ###############################################################################

custom-prompt/.clang-format

@@ -54,7 +54,7 @@ BreakBeforeInheritanceComma: false
 BreakInheritanceList: BeforeColon
 BreakBeforeTernaryOperators: true
 BreakConstructorInitializersBeforeComma: false
-BreakConstructorInitializers: BeforeComma
+BreakConstructorInitializers: AfterColon
 BreakAfterJavaFieldAnnotations: false
 BreakStringLiterals: true
 ColumnLimit:     119

custom-prompt/Makefile

@@ -1,7 +1,8 @@
 CC = gcc
-CFLAGS = -fstrict-aliasing -std=c11 -Wall -Wextra
-CXXFLAGS = -fstrict-aliasing -std=c++17 -Wall -Wextra
-LDLIBS = -lstdc++
+CPPFLAGS = $(shell pkg-config --cflags libgit2)
+CFLAGS = -fstrict-aliasing -std=c11 -Wall -Wextra -Wno-unused-parameter
+CXXFLAGS = -fstrict-aliasing -std=c++17 -Wall -Wextra -Wno-unused-parameter
+LDLIBS = -lstdc++ $(shell pkg-config --libs libgit2)
 
 MainSource = custom-prompt.cc
 MainBashObject = custom-bash-prompt.o
@@ -10,12 +11,7 @@ MainZshObject = custom-zsh-prompt.o
 MainZshExecutable = bin/$(MainZshObject:.o=)
 GetActiveWidObjects = get_active_wid_linux.o get_active_wid_windows.o
 
-ifeq "$(OS)" "Windows_NT"
-    # When building using something other than Visual Studio, the shared
-    # libraries the executables are linked with may lie in folders Windows does
-    # not typically search. Avoid the hassle of fixing that.
-    LDFLAGS += -static
-else
+ifneq "$(OS)" "Windows_NT"
     UNAME = $(shell uname)
     ifeq "$(UNAME)" "Linux"
         CPPFLAGS += $(shell pkg-config --cflags glib-2.0 libnotify x11)