escaping $ in build_flags

[jschoch]

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---

Configuration

Operating system: windwos

PlatformIO Version (platformio --version):

Description of problem

using env.StringifyMacro() doesn't escape special characters also it isn't obvious what the escapes are, for instance "$$" to escape "$" isn't obvious. "\$" produces "/$" which is also baffeling. The docs only say to escape characters they don't say how you do it.

Request: document escape characters and special characters used in .ini build_flags and env variables

[ivankravets]

Could you provide a platformio.ini example?

[jschoch]

example:

Import("env")
import os

secret = "123$$a$$"
# this insanity is required 
proper = "123$$$$$$$$a$$$$$$$$" 

# add macro definition for code to use in projenv (visible to src/ files) 
env.Append(CPPDEFINES=[
  ("WIFI_PWD", env.StringifyMacro(secret))
])

suck = env.StringifyMacro(secret)


print(" DOH " + suck + " --- " + secret + "\n");

main.cpp

#include <Arduino.h>

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
}

void loop() {
  // put your main code here, to run repeatedly:
  #pragma message( WIFI_PWD);
  printf("thing: %s",WIFI_PWD);
  delay(1000);
}

[ivankravets]

@bdbaddog, @mwichmann, sorry for disturbing you directly.

Could you share with us any ideas on how to disable SCons variable substitution for the CPPDEFINE/Macro?

The env.Append(CPPDEFINES=[("WIFI_PWD", "123$$a$$")]) produces ... -DWIFI_PWD=123$ ... in a verbose mode where SCons tries to evaluate $xxxx.

Thanks in advance.

[bdbaddog]

Two options:

1. create your own escape function and set via env['ESCAPE'] (See manpage)
2. Change env.Append(CPPDEFINES=[("WIFI_PWD", "123$$a$$")]) to env.Append(CPPDEFINES=[("WIFI_PWD", "123\$$\$$a\$$\$$")])
   $$ substitutes to $, then the \ should escape it for the SHELL.

I'd say go ahead and add your example to this existing github issue (if you agree that it's basically the same issue?) https://github.com/SCons/scons/issues/1093

[ivankravets]

@bdbaddog, thanks for the prompt help!

The 2nd option will work well for us. I tried it and it still "eats" char a. The env.Append(CPPDEFINES=[("WIFI_PWD", "123\$$\$$a\$$\$$")]) produces -DWIFI_PWD=123\$\\$\$.

[mwichmann]

Also look into Literal

https://scons.org/doc/production/HTML/scons-man.html#f-Literal

I believe we've used that form to get around the irritating ORIGIN token for the binutils linker, like Literal('\\\\$$ORIGIN') (that appears in one of the tests).

[ivankravets]

@mwichmann , I tried it with ("WIFI_PWD", env.Literal('\\\\$$ORIGIN')) and it produces -DWIFI_PWD=\\.