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

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

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

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@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
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gvanrossum reviewed Mar 3, 2021
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Is this safe? While match x is invalid, match (x) should be a function call.

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pablogsal commented Mar 3, 2021

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

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pablogsal commented Mar 3, 2021

I will add also a test for that case

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pablogsal commented Mar 3, 2021

Fixed in the last ammend

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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.

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pablogsal commented Mar 3, 2021

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
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I don't understand why e.g. match(1) doesn't reach invalid_match_stmt, so I'm still concerned.

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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.

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

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

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pablogsal commented Mar 5, 2021

Does invalid_match still need to be guarded with CHECK_VERSION?

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

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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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