Hello,

textcomp.sty contains:
  \DeclareEncodingSubset{TS1}{cmr}{0}
  ...
  \DeclareEncodingSubset{TS1}{ptmj}{4}
However, I miss entries for the new font families
of Latin Modern and TeX Gyre.

Both seems to support "0":

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{tgheros}
\usepackage{textcomp}
\DeclareEncodingSubset{TS1}{lmr}{0}
\DeclareEncodingSubset{TS1}{qhv}{0}
\begin{document}
\textrm{\textcircled{a}}
\textsf{\textcircled{a}}
\end{document}

Without the subset declarations there is a warning for qhv (tgheros):
  LaTeX Font Warning: Font shape `OMS/qhv/m/n' undefined
  (Font)              using `OMS/cmsy/m/n' instead on input line 10.

With the declarations the example runs without errors and
warnings, but the circle is a little small.

Yours sincerely
  Heiko <[log in to unmask]>