Rename all ParseSess variables/fields/lifetimes as psess.

Existing names for values of this type are `sess`, `parse_sess`,
`parse_session`, and `ps`. `sess` is particularly annoying because
that's also used for `Session` values, which are often co-located, and
it can be difficult to know which type a value named `sess` refers to.
(That annoyance is the main motivation for this change.) `psess` is nice
and short, which is good for a name used this much.

The commit also renames some `parse_sess_created` values as
`psess_created`.

compiler/rustc_expand/src/base.rs

@@ -1135,13 +1135,13 @@ impl<'a> ExtCtxt<'a> {
         expand::MacroExpander::new(self, true)
     }
     pub fn new_parser_from_tts(&self, stream: TokenStream) -> parser::Parser<'a> {
-        rustc_parse::stream_to_parser(&self.sess.parse_sess, stream, MACRO_ARGUMENTS)
+        rustc_parse::stream_to_parser(&self.sess.psess, stream, MACRO_ARGUMENTS)
     }
     pub fn source_map(&self) -> &'a SourceMap {
-        self.sess.parse_sess.source_map()
+        self.sess.psess.source_map()
     }
-    pub fn parse_sess(&self) -> &'a ParseSess {
-        &self.sess.parse_sess
+    pub fn psess(&self) -> &'a ParseSess {
+        &self.sess.psess
     }
     pub fn call_site(&self) -> Span {
         self.current_expansion.id.expn_data().call_site
@@ -1216,11 +1216,7 @@ impl<'a> ExtCtxt<'a> {
 /// Resolves a `path` mentioned inside Rust code, returning an absolute path.
 ///
 /// This unifies the logic used for resolving `include_X!`.
-pub fn resolve_path(
-    sess: &Session,
-    path: impl Into<PathBuf>,
-    span: Span,
-) -> PResult<'_, PathBuf> {
+pub fn resolve_path(sess: &Session, path: impl Into<PathBuf>, span: Span) -> PResult<'_, PathBuf> {
     let path = path.into();
 
     // Relative paths are resolved relative to the file in which they are found
@@ -1281,7 +1277,7 @@ pub fn expr_to_spanned_string<'a>(
                 Ok((err, true))
             }
             Ok(ast::LitKind::Err(guar)) => Err(guar),
-            Err(err) => Err(report_lit_error(&cx.sess.parse_sess, err, token_lit, expr.span)),
+            Err(err) => Err(report_lit_error(&cx.sess.psess, err, token_lit, expr.span)),
             _ => Ok((cx.dcx().struct_span_err(expr.span, err_msg), false)),
         },
         ast::ExprKind::Err(guar) => Err(guar),
@@ -1487,7 +1483,7 @@ fn pretty_printing_compatibility_hack(item: &Item, sess: &Session) -> bool {
                             };
 
                             if crate_matches {
-                                sess.parse_sess.buffer_lint_with_diagnostic(
+                                sess.psess.buffer_lint_with_diagnostic(
                                         PROC_MACRO_BACK_COMPAT,
                                         item.ident.span,
                                         ast::CRATE_NODE_ID,