Hi community. This is my first post here. I updated R to v4.0.2 and configured the C++ toolchain, following the RStan Getting Started page.

When testing the install with the tutorial-provided eight schools example, the model appears stuck, there’s no better word for it. No warnings are produced initially, and the CPU running suggests the chains are going. But this continues for as much as 6hrs. If I escape out of the process, I get these warnings:

```
> stan_samples <- stan(model_code = model_string, data = list(y = y, n = length(y)) )
Warning messages:
1: In system(paste(CXX, ARGS), ignore.stdout = TRUE, ignore.stderr = TRUE) :
system call failed: Undefined error: 0
2: In system(paste(CXX, ARGS), ignore.stdout = TRUE, ignore.stderr = TRUE) :
error in running command
```

I’m using the R interface, not R Studio. System info is as follows:

R version 4.0.2 (2020-06-22) – “Taking Off Again”

Copyright © 2020 The R Foundation for Statistical Computing

Platform: x86_64-apple-darwin17.0 (64-bit)

[R.app GUI 1.72 (7847) x86_64-apple-darwin17.0]

MacOS Mojave 10.14.6

Reproduced from RStan Getting Started

```
// saved as schools.stan
data {
int<lower=0> J; // number of schools
real y[J]; // estimated treatment effects
real<lower=0> sigma[J]; // standard error of effect estimates
}
parameters {
real mu; // population treatment effect
real<lower=0> tau; // standard deviation in treatment effects
vector[J] eta; // unscaled deviation from mu by school
}
transformed parameters {
vector[J] theta = mu + tau * eta; // school treatment effects
}
model {
target += normal_lpdf(eta | 0, 1); // prior log-density
target += normal_lpdf(y | theta, sigma); // log-likelihood
}
```

```
schools_dat <- list(J = 8,
y = c(28, 8, -3, 7, -1, 1, 18, 12),
sigma = c(15, 10, 16, 11, 9, 11, 10, 18))
fit <- stan(file = 'schools.stan', data = schools_dat)
```

Thanks for any help, very much appreciated.