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bpo-42128: Add 'missing :' syntax error message to match statements#24733

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pablogsal merged 2 commits into
python:masterfrom
pablogsal:match-colon
Mar 18, 2021
Merged

bpo-42128: Add 'missing :' syntax error message to match statements#24733
pablogsal merged 2 commits into
python:masterfrom
pablogsal:match-colon

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@pablogsal

@pablogsal pablogsal commented Mar 3, 2021 •
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@pablogsal pablogsal requested a review from lysnikolaou as a code owner March 3, 2021 19:20
@pablogsal pablogsal requested a review from brandtbucher March 3, 2021 19:20
gvanrossum
gvanrossum reviewed Mar 3, 2021
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Is this safe? While match x is invalid, match (x) should be a function call.

@pablogsal

pablogsal commented Mar 3, 2021

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Is this safe? While match x is invalid, match (x) should be a function call.

Hummmm, that's a good point. if match(x) is by itself this will probably fail. Let me think how can we workaround that

@pablogsal

pablogsal commented Mar 3, 2021

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I will add also a test for that case

@pablogsal

pablogsal commented Mar 3, 2021

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Fixed in the last ammend

@brandtbucher

brandtbucher commented Mar 3, 2021 •
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For my own understanding... does double-ampersand raise a SyntaxError at that token's location suggesting it if it doesn't exist? That's really nice.

@pablogsal

pablogsal commented Mar 3, 2021

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For my own understanding... does double-ampersand raise a SyntaxError at that token's location suggesting it if it doesn't exist? That's really nice.

Yeah, is a "forced token" operator. Notice that it also hard-stops the parsing: no other alternative will be considered.

@pablogsal pablogsal requested a review from gvanrossum March 3, 2021 21:30
gvanrossum
gvanrossum reviewed Mar 3, 2021
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I don't understand why e.g. match(1) doesn't reach invalid_match_stmt, so I'm still concerned.

@pablogsal

pablogsal commented Mar 4, 2021 •
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I don't understand why e.g. match(1) doesn't reach invalid_match_stmt, so I'm still concerned.

The invalid_* rules are now only checked in a second pass of the parser if the first one fails. This was done mainly for speed, but allows to introduce these kind of error messages with early failures.

gvanrossum
gvanrossum approved these changes Mar 4, 2021
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Ehh! I totally forgot about that!

@brandtbucher

brandtbucher commented Mar 4, 2021 •
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Does invalid_match still need to be guarded with CHECK_VERSION?

@pablogsal

pablogsal commented Mar 5, 2021

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Does invalid_match still need to be guarded with CHECK_VERSION?

Not really because is a syntax error, but it certainly won't hurt.

brandtbucher
brandtbucher approved these changes Mar 18, 2021
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Thanks!

@pablogsal pablogsal merged commit 08fb8ac into python:master Mar 18, 2021
@pablogsal pablogsal deleted the match-colon branch March 18, 2021 01:03
jab added a commit to jab/cpython that referenced this pull request Mar 20, 2021
@jab
Merge branch 'master' into justin39/aiter-c
97d06e5 
* master: (129 commits)
  bpo-43452: Micro-optimizations to PyType_Lookup (pythonGH-24804)
  bpo-43517: Fix false positive in detection of circular imports (python#24895)
  bpo-43494: Make some minor changes to lnotab notes (pythonGH-24861)
  Mention that code.co_lnotab is deprecated in what's new for 3.10. (python#24902)
  bpo-43244: Remove symtable.h header file (pythonGH-24910)
  bpo-43466: Add --with-openssl-rpath configure option (pythonGH-24820)
  Fix a typo in c-analyzer (pythonGH-24468)
  bpo-41561: Add workaround for Ubuntu's custom security level (pythonGH-24915)
  bpo-43521: Allow ast.unparse with empty sets and NaN (pythonGH-24897)
  bpo-43244: Remove the PyAST_Validate() function (pythonGH-24911)
  bpo-43541: Fix PyEval_EvalCodeEx() regression (pythonGH-24918)
  bpo-43244: Fix test_peg_generators on Windows (pythonGH-24913)
  bpo-39342: Expose X509_V_FLAG_ALLOW_PROXY_CERTS in ssl module (pythonGH-18011)
  bpo-43244: Fix test_peg_generator for PyAST_Validate() (pythonGH-24912)
  bpo-42128: Add 'missing :' syntax error message to match statements (pythonGH-24733)
  bpo-43244: Add pycore_ast.h header file (pythonGH-24908)
  bpo-43244: Rename pycore_ast.h to pycore_ast_state.h (pythonGH-24907)
  Remove unnecessary imports in the grammar parser (pythonGH-24904)
  bpo-35883: Py_DecodeLocale() escapes invalid Unicode characters (pythonGH-24843)
  Add PEP 626 to what's new in 3.10. (python#24892)
  ...
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@gvanrossum gvanrossum gvanrossum approved these changes

@brandtbucher brandtbucher brandtbucher approved these changes

@lysnikolaou lysnikolaou Awaiting requested review from lysnikolaou

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@pablogsal @brandtbucher @gvanrossum @the-knights-who-say-ni @bedevere-bot