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+Building Bash 1.14.7 on a modern system
+=======================================
+---
+date: "2015-03-18"
+---
+
+In a previous revision of my [Bash arrays post](./bash-arrays.html), I wrote:
+
+> Bash 1.x won't compile with modern GCC, so I couldn't verify how it
+> behaves.
+
+I recall spending a little time fighting with it, but apparently I
+didn't try very hard: getting Bash 1.14.7 to build on a modern box is
+mostly just adjusting it to use `stdarg` instead of the
+no-longer-implemented `varargs`.  There's also a little fiddling with
+the pre-autoconf automatic configuration.
+
+## stdarg
+
+Converting to `stdarg` is pretty simple: For each variadic function
+(functions that take a variable number of arguments), follow these steps:
+
+1. Replace `#include <varargs.h>` with `#include <stdarg.h>`
+2. Replace `function_name (va_alist) va_dcl` with
+   `function_name (char *format, ...)`.
+3. Removing the declaration and assignment for `format` from the
+   function body.
+4. Replace `va_start (args);` with `va_start (args, format);` in the
+   function bodies.
+5. Replace `function_name ();` with `function_name (char *, ...)` in
+   header files and/or at the top of C files.
+
+There's one function that uses the variable name `control` instead of
+`format`.
+
+I've prepared [a patch](./bash-1.14.7-gcc4-stdarg.patch) that does this.
+
+## Configuration
+
+Instead of using autoconf-style tests to test for compiler and
+platform features, Bash 1 used the file `machines.h` that had
+`#ifdefs` and a huge database of of different operating systems for
+different platforms.  It's gross.  And quite likely won't handle your
+modern operating system.
+
+I made these two small changes to `machines.h` to get it to work
+correctly on my box:
+
+1. Replace `#if defined (i386)` with
+   `#if defined (i386) || defined (__x86_64__)`.  The purpose of this
+   is obvious.
+2. Add `#define USE_TERMCAP_EMULATION` to the section for Linux [sic]
+   on i386
+   (`#  if !defined (done386) && (defined (__linux__) || defined (linux))`.
+   What this does is tell it to use link against libcurses to use
+   curses termcap emulation, instead of linking against libtermcap
+   (which doesn't exist on modern GNU/Linux systems).
+
+Again, I've prepared [a patch](./bash-1.14.7-machines-config.patch)
+that does this.
+
+## Building
+
+With those adjustments, it should build, but with quite a few
+warnings.   Making a couple of changes to `CFLAGS` should fix that:
+
+    make CFLAGS='-O -g -Werror -Wno-int-to-pointer-cast -Wno-pointer-to-int-cast -Wno-deprecated-declarations -include stdio.h -include stdlib.h -include string.h -Dexp2=bash_exp2'
+
+That's a doozy!  Let's break it down:
+
+- `-O -g` The default value for CFLAGS (defined in `cpp-Makefile`)
+- `-Werror` Treat warnings as errors; force us to deal with any issues.
+- `-Wno-int-to-pointer-cast -Wno-pointer-to-int-cast` Allow casting
+  between integers and pointers.  Unfortunately, the way this version
+  of Bash was designed requires this.
+- `-Wno-deprecated-declarations`.  The `getwd` function in `unistd.h`
+  is considered deprecated (use `getcwd` instead).  However, if
+  `getcwd` is available, Bash uses it's own `getwd` wrapper around
+  `getcwd` (implemented in `general.c`), and only uses the signature
+  from `unistd.h`, not the actually implementation from libc.
+- `-include stdio.h -include stdlib.h -include string.h` Several files
+  are missing these header file includes.  If not for `-Werror`, the
+  default function signature fallbacks would work.
+- `-Dexp2=bash_exp2` Avoid a conflict between the parser's `exp2`
+  helper function and `math.h`'s base-2 exponential function.
+
+Have fun, software archaeologists!