[Chapel Merge] Allow compile-time indexing for param strings and

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Branch: refs/heads/main
Revision: 691814f
Author: e-kayrakli
Link: Allow compile-time indexing for param strings and bytes by e-kayrakli · Pull Request #19702 · chapel-lang/chapel · GitHub
Log Message:

Merge pull request #19702 from e-kayrakli/param-string-index

Allow compile-time indexing for param strings and bytes

With this PR, indexing string and bytes using [] or .item is a
compile-time operation. As such, the results of such operations can be stored in
params.

Resolves Indexing a param string/bytes with a param int should return a param · Issue #16895 · chapel-lang/chapel · GitHub

Copying from that issue, the following is legal with this PR:

param s = "chapel";
param i = 1;
param ss = s[i];   // this was not a compile time operation
compilerWarning(ss);

Implementation details:

  • Adds two primitives PRIM_STRING_ITEM and PRIM_BYTES_ITEM
    • These primitives are post-folded into string or bytes symbols respectively.
  • This involves some refactoring in postfold to reuse some of the existing
    logic used for post-folding PRIM_ASCII.
  • Adds chpl_enc_codepoint_at_idx to in the shared runtime header to support
    the PRIM_STRING_ITEM primitive.

[Reviewed by @mppf]

Test:

  • [x] standard linux64

    Modified Files:
    A test/types/string/param-index-bytes-item.good
    A test/types/string/param-index-bytes.good
    A test/types/string/param-index-string.good
    A test/types/string/param-index.chpl
    A test/types/string/param-index.compopts
    A test/types/string/param-index.noexec
    M compiler/AST/primitive.cpp
    M compiler/dyno/include/chpl/uast/prim-ops-list.h
    M compiler/resolution/postFold.cpp
    M modules/internal/Bytes.chpl
    M modules/internal/String.chpl
    M runtime/include/encoding/encoding-support.h
    M test/parsing/stringLiteralIndex/stringBytesLiteralIndexOOB1.good
    M test/parsing/stringLiteralIndex/stringBytesLiteralIndexOOB2.good

    Compare: Comparing e2137e1ed125...691814f0cfc6 · chapel-lang/chapel · GitHub