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bpo-35808: Retire pgen and use pgen2 to generate the parser (pythonGH…
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…-11814)

Pgen is the oldest piece of technology in the CPython repository, building it requires various #if[n]def PGEN hacks in other parts of the code and it also depends more and more on CPython internals. This commit removes the old pgen C code and replaces it for a new version implemented in pure Python. This is a modified and adapted version of lib2to3/pgen2 that can generate grammar files compatibles with the current parser.

This commit also eliminates all the #ifdef and code branches related to pgen, simplifying the code and making it more maintainable. The regen-grammar step now uses $(PYTHON_FOR_REGEN) that can be any version of the interpreter, so the new pgen code maintains compatibility with older versions of the interpreter (this also allows regenerating the grammar with the current CI solution that uses Python3.5). The new pgen Python module also makes use of the Grammar/Tokens file that holds the token specification, so is always kept in sync and avoids having to maintain duplicate token definitions.
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pablogsal authored Mar 1, 2019
1 parent 7eebbbd commit 1f24a71
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Showing 27 changed files with 1,480 additions and 2,684 deletions.
2 changes: 0 additions & 2 deletions .gitignore
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Expand Up @@ -73,8 +73,6 @@ PCbuild/arm32/
PCbuild/obj/
PCbuild/win32/
.purify
Parser/pgen
Parser/pgen.exe
__pycache__
autom4te.cache
build/
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18 changes: 0 additions & 18 deletions Include/metagrammar.h

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3 changes: 0 additions & 3 deletions Include/parsetok.h
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Expand Up @@ -12,10 +12,7 @@ extern "C" {

typedef struct {
int error;
#ifndef PGEN
/* The filename is useless for pgen, see comment in tok_state structure */
PyObject *filename;
#endif
int lineno;
int offset;
char *text; /* UTF-8-encoded string */
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18 changes: 0 additions & 18 deletions Include/pgen.h

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42 changes: 4 additions & 38 deletions Makefile.pre.in
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Expand Up @@ -290,40 +290,21 @@ LIBFFI_INCLUDEDIR= @LIBFFI_INCLUDEDIR@

##########################################################################
# Parser
PGEN= Parser/pgen$(EXE)

POBJS= \
Parser/acceler.o \
Parser/grammar1.o \
Parser/listnode.o \
Parser/node.o \
Parser/parser.o \
Parser/bitset.o \
Parser/metagrammar.o \
Parser/firstsets.o \
Parser/grammar.o \
Parser/token.o \
Parser/pgen.o

PARSER_OBJS= $(POBJS) Parser/myreadline.o Parser/parsetok.o Parser/tokenizer.o

PGOBJS= \
Objects/obmalloc.o \
Python/dynamic_annotations.o \
Python/mysnprintf.o \
Python/pyctype.o \
Parser/tokenizer_pgen.o \
Parser/printgrammar.o \
Parser/parsetok_pgen.o \
Parser/pgenmain.o

PARSER_HEADERS= \
$(srcdir)/Parser/parser.h \
$(srcdir)/Include/parsetok.h \
$(srcdir)/Parser/tokenizer.h

PGENOBJS= $(POBJS) $(PGOBJS)

##########################################################################
# Python

Expand Down Expand Up @@ -802,31 +783,18 @@ Python/sysmodule.o: $(srcdir)/Python/sysmodule.c Makefile

$(IO_OBJS): $(IO_H)

$(PGEN): $(PGENOBJS)
$(CC) $(OPT) $(PY_CORE_LDFLAGS) $(PGENOBJS) $(LIBS) -o $(PGEN)

.PHONY: regen-grammar
regen-grammar: $(PGEN)
regen-grammar: regen-token
# Regenerate Include/graminit.h and Python/graminit.c
# from Grammar/Grammar using pgen
@$(MKDIR_P) Include
$(PGEN) $(srcdir)/Grammar/Grammar \
$(PYTHON_FOR_REGEN) -m Parser.pgen $(srcdir)/Grammar/Grammar \
$(srcdir)/Grammar/Tokens \
$(srcdir)/Include/graminit.h.new \
$(srcdir)/Python/graminit.c.new
$(UPDATE_FILE) $(srcdir)/Include/graminit.h $(srcdir)/Include/graminit.h.new
$(UPDATE_FILE) $(srcdir)/Python/graminit.c $(srcdir)/Python/graminit.c.new

Parser/grammar.o: $(srcdir)/Parser/grammar.c \
$(srcdir)/Include/token.h \
$(srcdir)/Include/grammar.h
Parser/metagrammar.o: $(srcdir)/Parser/metagrammar.c

Parser/tokenizer_pgen.o: $(srcdir)/Parser/tokenizer.c
Parser/parsetok_pgen.o: $(srcdir)/Parser/parsetok.c
Parser/printgrammar.o: $(srcdir)/Parser/printgrammar.c

Parser/pgenmain.o: $(srcdir)/Include/parsetok.h

.PHONY=regen-ast
regen-ast:
# Regenerate Include/Python-ast.h using Parser/asdl_c.py -h
Expand Down Expand Up @@ -1016,7 +984,6 @@ PYTHON_HEADERS= \
$(srcdir)/Include/longobject.h \
$(srcdir)/Include/marshal.h \
$(srcdir)/Include/memoryobject.h \
$(srcdir)/Include/metagrammar.h \
$(srcdir)/Include/methodobject.h \
$(srcdir)/Include/modsupport.h \
$(srcdir)/Include/moduleobject.h \
Expand All @@ -1028,7 +995,6 @@ PYTHON_HEADERS= \
$(srcdir)/Include/osdefs.h \
$(srcdir)/Include/osmodule.h \
$(srcdir)/Include/patchlevel.h \
$(srcdir)/Include/pgen.h \
$(srcdir)/Include/pgenheaders.h \
$(srcdir)/Include/pyarena.h \
$(srcdir)/Include/pycapsule.h \
Expand Down Expand Up @@ -1771,7 +1737,7 @@ profile-removal:
rm -f profile-run-stamp

clobber: clean profile-removal
-rm -f $(BUILDPYTHON) $(PGEN) $(LIBRARY) $(LDLIBRARY) $(DLLLIBRARY) \
-rm -f $(BUILDPYTHON) $(LIBRARY) $(LDLIBRARY) $(DLLLIBRARY) \
tags TAGS \
config.cache config.log pyconfig.h Modules/config.c
-rm -rf build platform
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@@ -0,0 +1,2 @@
Retire pgen and use a modified version of pgen2 to generate the parser.
Patch by Pablo Galindo.
8 changes: 0 additions & 8 deletions Misc/coverity_model.c
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Expand Up @@ -92,14 +92,6 @@ wchar_t *Py_DecodeLocale(const char* arg, size_t *size)
return w;
}

/* Parser/pgenmain.c */
grammar *getgrammar(const char *filename)
{
grammar *g;
__coverity_tainted_data_sink__(filename);
return g;
}

/* Python/marshal.c */

static Py_ssize_t r_string(char *s, Py_ssize_t n, RFILE *p)
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6 changes: 0 additions & 6 deletions PCbuild/pythoncore.vcxproj
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Expand Up @@ -161,7 +161,6 @@
<ClInclude Include="..\Include\longobject.h" />
<ClInclude Include="..\Include\marshal.h" />
<ClInclude Include="..\Include\memoryobject.h" />
<ClInclude Include="..\Include\metagrammar.h" />
<ClInclude Include="..\Include\methodobject.h" />
<ClInclude Include="..\Include\modsupport.h" />
<ClInclude Include="..\Include\moduleobject.h" />
Expand All @@ -175,7 +174,6 @@
<ClInclude Include="..\Include\osmodule.h" />
<ClInclude Include="..\Include\parsetok.h" />
<ClInclude Include="..\Include\patchlevel.h" />
<ClInclude Include="..\Include\pgen.h" />
<ClInclude Include="..\Include\pgenheaders.h" />
<ClInclude Include="..\Include\pyhash.h" />
<ClInclude Include="..\Include\py_curses.h" />
Expand Down Expand Up @@ -372,12 +370,8 @@
<ClCompile Include="..\Objects\unicodeobject.c" />
<ClCompile Include="..\Objects\weakrefobject.c" />
<ClCompile Include="..\Parser\acceler.c" />
<ClCompile Include="..\Parser\bitset.c" />
<ClCompile Include="..\Parser\firstsets.c" />
<ClCompile Include="..\Parser\grammar.c" />
<ClCompile Include="..\Parser\grammar1.c" />
<ClCompile Include="..\Parser\listnode.c" />
<ClCompile Include="..\Parser\metagrammar.c" />
<ClCompile Include="..\Parser\myreadline.c" />
<ClCompile Include="..\Parser\node.c" />
<ClCompile Include="..\Parser\parser.c" />
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18 changes: 0 additions & 18 deletions PCbuild/pythoncore.vcxproj.filters
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Expand Up @@ -234,9 +234,6 @@
<ClInclude Include="..\Include\memoryobject.h">
<Filter>Include</Filter>
</ClInclude>
<ClInclude Include="..\Include\metagrammar.h">
<Filter>Include</Filter>
</ClInclude>
<ClInclude Include="..\Include\methodobject.h">
<Filter>Include</Filter>
</ClInclude>
Expand Down Expand Up @@ -270,9 +267,6 @@
<ClInclude Include="..\Include\patchlevel.h">
<Filter>Include</Filter>
</ClInclude>
<ClInclude Include="..\Include\pgen.h">
<Filter>Include</Filter>
</ClInclude>
<ClInclude Include="..\Include\pgenheaders.h">
<Filter>Include</Filter>
</ClInclude>
Expand Down Expand Up @@ -836,24 +830,12 @@
<ClCompile Include="..\Parser\acceler.c">
<Filter>Parser</Filter>
</ClCompile>
<ClCompile Include="..\Parser\bitset.c">
<Filter>Parser</Filter>
</ClCompile>
<ClCompile Include="..\Parser\firstsets.c">
<Filter>Parser</Filter>
</ClCompile>
<ClCompile Include="..\Parser\grammar.c">
<Filter>Parser</Filter>
</ClCompile>
<ClCompile Include="..\Parser\grammar1.c">
<Filter>Parser</Filter>
</ClCompile>
<ClCompile Include="..\Parser\listnode.c">
<Filter>Parser</Filter>
</ClCompile>
<ClCompile Include="..\Parser\metagrammar.c">
<Filter>Parser</Filter>
</ClCompile>
<ClCompile Include="..\Parser\myreadline.c">
<Filter>Parser</Filter>
</ClCompile>
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66 changes: 0 additions & 66 deletions Parser/bitset.c

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