How to set sans serif with cmbright package?

Question

I am starting to use XeLaTeX. I tried, as an example, to use cmbright. But I do not obtain a sans serif output. Do I need to tell something else in the preamble?

\documentclass[10pt,a4paper]{article}

\usepackage{fontspec}
\usepackage{cmbright}
\usepackage{polyglossia}
\setmainlanguage{french}


\author{Plop}
\title{Test fonts xelatex}

\usepackage{lipsum}

\begin{document}

\maketitle

\lipsum[1-4]

\end{document}

Answer 1

The package cmbright doesn't make sense with XeLaTeX/fontspec, because it loads legacy fonts.

You can use the CM-Unicode version of CMBright.

\documentclass[10pt,a4paper]{article}

\usepackage{fontspec}
\usepackage{polyglossia}
\setmainlanguage{french}

\setmainfont{cmunb}[
  Extension=.otf,
  UprightFont=*mr,
  ItalicFont=*mo,
  BoldFont=*bx,
  BoldItalicFont=*xo,
]

\author{Plop}
\title{Test fonts xelatex}

\usepackage{lipsum}

\begin{document}

\maketitle

Abc \textbf{Abc} \textit{Abc} \textbf{\textit{Abc}}

\lipsum[1-4]

\end{document}

You may want to use semibold, in this case change the declaration into

\setmainfont{cmunb}[
  Extension=.otf,
  UprightFont=*mr,
  ItalicFont=*mo,
  BoldFont=*so,       % semibold
  BoldItalicFont=*sr, % semibold oblique
]

If the CM-Unicode fonts are installed also as system fonts, you can declare them more easily by name

\setmainfont{CMU Bright}

that would choose the semibold variant. For getting the bold variant use

\setmainfont{CMU Bright}[
  BoldFont=* Bold Extended,
  BoldItalicFont=* Bold Extended Oblique,
]