This is my patch

[ 587993 ] SET_LINENO killer

Remove SET_LINENO.  Tracing is now supported by inspecting co_lnotab.

Many sundry changes to document and adapt to this change.

4 files changed, 52 insertions, 24 deletions

diff --git a/Doc/lib/libdis.tex b/Doc/lib/libdis.tex
index 16b692d..567c0ee 100644
--- a/Doc/lib/libdis.tex
+++ b/Doc/lib/libdis.tex
@@ -23,17 +23,15 @@ the following command can be used to get the disassembly of
 
 \begin{verbatim}
 >>> dis.dis(myfunc)
-          0 SET_LINENO          1
-
-          3 SET_LINENO          2
-          6 LOAD_GLOBAL         0 (len)
-          9 LOAD_FAST           0 (alist)
-         12 CALL_FUNCTION       1
-         15 RETURN_VALUE   
-         16 LOAD_CONST          0 (None)
-         19 RETURN_VALUE   
+  2           0 LOAD_GLOBAL              0 (len)
+              3 LOAD_FAST                0 (alist)
+              6 CALL_FUNCTION            1
+              9 RETURN_VALUE        
+             10 RETURN_NONE
 \end{verbatim}
 
+(The ``2'' is a line number).
+
 The \module{dis} module defines the following functions and constants:
 
 \begin{funcdesc}{dis}{\optional{bytesource}}
@@ -56,6 +54,7 @@ Disassembles a code object, indicating the last instruction if \var{lasti}
 was provided.  The output is divided in the following columns:
 
 \begin{enumerate}
+\item the line number, for the first instruction of each line
 \item the current instruction, indicated as \samp{-->},
 \item a labelled instruction, indicated with \samp{>\code{>}},
 \item the address of the instruction,
@@ -402,6 +401,14 @@ is evaluated, the locals are passed to the class definition.
 Returns with TOS to the caller of the function.
 \end{opcodedesc}
 
+\begin{opcodedesc}{RETURN_NONE}{}
+Returns \constant{None} to the caller of the function.  This opcode is
+generated as the last opcode of every function and only then, for
+reasons to do with tracing support.  See the comments in the function
+\cfunction{maybe_call_line_trace} in \file{Python/ceval.c} for the
+gory details.  \versionadded{2.3}.
+\end{opcodedesc}
+
 \begin{opcodedesc}{YIELD_VALUE}{}
 Pops \code{TOS} and yields it from a generator.
 \end{opcodedesc}
@@ -621,7 +628,7 @@ free variable storage.
 \end{opcodedesc}
 
 \begin{opcodedesc}{SET_LINENO}{lineno}
-Sets the current line number to \var{lineno}.
+This opcode is obsolete.
 \end{opcodedesc}
 
 \begin{opcodedesc}{RAISE_VARARGS}{argc}
diff --git a/Doc/lib/libtraceback.tex b/Doc/lib/libtraceback.tex
index 2b20b0c..a74613b 100644
--- a/Doc/lib/libtraceback.tex
+++ b/Doc/lib/libtraceback.tex
@@ -118,10 +118,10 @@ A shorthand for \code{format_list(extract_stack(\var{f}, \var{limit}))}.
 
 \begin{funcdesc}{tb_lineno}{tb}
 This function returns the current line number set in the traceback
-object.  This is normally the same as the \code{\var{tb}.tb_lineno}
-field of the object, but when optimization is used (the -O flag) this
-field is not updated correctly; this function calculates the correct
-value.
+object.  This function was necessary because in versions of Python
+prior to 2.3 when the \programopt{O} flag was passed to Python the
+\code{\var{tb}.tb_lineno} was not updated correctly.  This function
+has no use in versions past 2.3.
 \end{funcdesc}
 
 
diff --git a/Doc/tut/tut.tex b/Doc/tut/tut.tex
index c6081c6..4bc571a 100644
--- a/Doc/tut/tut.tex
+++ b/Doc/tut/tut.tex
@@ -2340,12 +2340,11 @@ Some tips for experts:
 
 \item
 When the Python interpreter is invoked with the \programopt{-O} flag,
-optimized code is generated and stored in \file{.pyo} files.
-The optimizer currently doesn't help much; it only removes
-\keyword{assert} statements and \code{SET_LINENO} instructions.
-When \programopt{-O} is used, \emph{all} bytecode is optimized;
-\code{.pyc} files are ignored and \code{.py} files are compiled to
-optimized bytecode.
+optimized code is generated and stored in \file{.pyo} files.  The
+optimizer currently doesn't help much; it only removes
+\keyword{assert} statements.  When \programopt{-O} is used, \emph{all}
+bytecode is optimized; \code{.pyc} files are ignored and \code{.py}
+files are compiled to optimized bytecode.
 
 \item
 Passing two \programopt{-O} flags to the Python interpreter
diff --git a/Doc/whatsnew/whatsnew23.tex b/Doc/whatsnew/whatsnew23.tex
index 0d7d774..f919d7e 100644
--- a/Doc/whatsnew/whatsnew23.tex
+++ b/Doc/whatsnew/whatsnew23.tex
@@ -658,7 +658,6 @@ In 2.3, you get this:
 
 \end{itemize}
 
-
 %======================================================================
 \section{New and Improved Modules}
 
@@ -987,9 +986,9 @@ allocate objects, and \cfunction{PyObject_GC_Del} to deallocate them.
 when running Python's \file{configure} script.  (Contributed by Ondrej
 Palkovsky.)
 
-\item The  \csimplemacro{DL_EXPORT} and \csimplemacro{DL_IMPORT} macros are now
-deprecated.  Initialization functions for Python extension modules
-should now be declared using the new macro
+\item The \csimplemacro{DL_EXPORT} and \csimplemacro{DL_IMPORT} macros
+are now deprecated.  Initialization functions for Python extension
+modules should now be declared using the new macro
 \csimplemacro{PyMODINIT_FUNC}, while the Python core will generally
 use the \csimplemacro{PyAPI_FUNC} and \csimplemacro{PyAPI_DATA}
 macros.
@@ -1076,6 +1075,29 @@ Finally, there are various miscellaneous fixes:
 \item The tools used to build the documentation now work under Cygwin
 as well as \UNIX.
 
+\item The \code{SET_LINENO} opcode has been removed.  Back in the
+mists of time, this opcode was needed to produce line numbers in
+tracebacks and support trace functions (for, e.g., \module{pdb}).
+Since Python 1.5, the line numbers in tracebacks have been computed
+using a different mechanism that works with ``python -O''.  For Python
+2.3 Michael Hudson implemented a similar scheme to determine when to
+call the trace function, removing the need for \code{SET_LINENO}
+entirely.
+
+Python code will be hard pushed to notice a difference from this
+change, apart from a slight speed up when python is run without
+\programopt{-O}.
+
+C extensions that access the \member{f_lineno} field of frame objects
+should instead call \code{PyCode_Addr2Line(f->f_code, f->f_lasti)}.
+This will have the added effect of making the code work as desired
+under ``python -O'' in earlier versions of Python.
+
+To make tracing work as expected, it was found necessary to add a new
+opcode, \cdata{RETURN_NONE}, to the VM.  If you want to know why, read
+the comments in the function \cfunction{maybe_call_line_trace} in
+\file{Python/ceval.c}.
+
 \end{itemize}