10 Commits

Author SHA1 Message Date
Nikita Popov
07f3388fff Revert "[clang] Implement instantiation context note for checking template parameters (#126088)"
This reverts commit a24523ac8dc07f3478311a5969184b922b520395.

This is causing significant compile-time regressions for C++ code, see:
https://github.com/llvm/llvm-project/pull/126088#issuecomment-2704874202
2025-03-10 10:32:08 +01:00
Matheus Izvekov
a24523ac8d
[clang] Implement instantiation context note for checking template parameters (#126088)
Instead of manually adding a note pointing to the relevant template
parameter to every relevant error, which is very easy to miss, this
patch adds a new instantiation context note, so that this can work using
RAII magic.

This fixes a bunch of places where these notes were missing, and is more
future-proof.

Some diagnostics are reworked to make better use of this note:
- Errors about missing template arguments now refer to the parameter
which is missing an argument.
- Template Template parameter mismatches now refer to template
parameters as parameters instead of arguments.

It's likely this will add the note to some diagnostics where the
parameter is not super relevant, but this can be reworked with time and
the decrease in maintenance burden makes up for it.

This bypasses the templight dumper for the new context entry, as the
tests are very hard to update.

This depends on #125453, which is needed to avoid losing the context
note for errors occuring during template argument deduction.
2025-03-06 14:58:42 -03:00
Matheus Izvekov
e29c085812
[clang] disallow narrowing when matching template template parameters (#124313)
This fixes the core issue described in P3579, following the design
intent of P0522 to not introduce any new cases where a template template
parameter match is allowed for a template which is not valid for all
possible uses.

With this patch, narrowing conversions are disallowed for TTP matching.

This reuses the existing machinery for diagnosing narrowing in a
converted constant expression.
Since P0522 is a DR and we apply it all the way back to C++98, this
brings that machinery to use in older standards, in this very narrow
scope of TTP matching.

This still doesn't solve the ambiguity when partial ordering NTTPs of
different integral types, this is blocked by a different bug which will
be fixed in a subsequent patch (but the test cases are added).
2025-01-28 15:51:17 -03:00
Fangrui Song
83ea47acd7 [test] Make tests pass regardless of gnu++14/gnu++17 default
GCC from 11 onwards defaults to -std=gnu++17 for C++ source files. We want to do the same
(https://discourse.llvm.org/t/c-objc-switch-to-gnu-17-as-the-default-dialect/64360).
Split RUN lines, adjust `-verify`, or add `__cplusplus < 201703L` or `-Wno-dynamic-exception-spec`,
so that tests will pass regardless of gnu++14/gnu++17 default.

We have a desire to mark a test compatible with multiple language standards.
There are ongoing discussions how to add markers in the long term:

* https://discourse.llvm.org/t/iterating-lit-run-lines/62596
* https://discourse.llvm.org/t/lit-run-a-run-line-multiple-times-with-different-replacements/64932

As a workaround in the short term, add lit substitutions `%std_cxx98-`,
`%std_cxx11-14`, etc. They can be used for tests which work across multiple
language standards. If a range has `n` standards, run lit multiple times, with
`LIT_CLANG_STD_GROUP=0`, `LIT_CLANG_STD_GROUP=1`, etc to cover all `n` standards.

Reviewed By: #clang-language-wg, aaron.ballman

Differential Revision: https://reviews.llvm.org/D131464
2022-09-04 05:29:32 +00:00
Douglas Gregor
b242683d99 Overhaul checking of non-type template arguments that should refer to
an object or function. Our previous checking was too lax, and ended up
allowing missing or extraneous address-of operators, among other
evils. The new checking provides better diagnostics and adheres more
closely to the standard.

Fixes PR6563 and PR6749.

llvm-svn: 100125
2010-04-01 18:32:35 +00:00
Daniel Dunbar
8fbe78f6fc Update tests to use %clang_cc1 instead of 'clang-cc' or 'clang -cc1'.
- This is designed to make it obvious that %clang_cc1 is a "test variable"
   which is substituted. It is '%clang_cc1' instead of '%clang -cc1' because it
   can be useful to redefine what gets run as 'clang -cc1' (for example, to set
   a default target).

llvm-svn: 91446
2009-12-15 20:14:24 +00:00
Douglas Gregor
e62e6a0191 Before checking a template template argument against its corresponding
template template parameter, substitute any prior template arguments
into the template template parameter. This, for example, allows us to
properly check the template template argument for a class such as:

  template<typename T, template<T Value> class X> struct Foo;

The actual implementation of this feature was trivial; most of the
change is dedicated to giving decent diagnostics when this
substitution goes horribly wrong. We now get a note like:

  note: while substituting prior template arguments into template
      template parameter 'X' [with T = float]

As part of this change, enabled some very pedantic checking when
comparing template template parameter lists, which shook out a bug in
our overly-eager checking of default arguments of template template
parameters. We now perform only minimal checking of such default
arguments when they are initially parsed.

llvm-svn: 86864
2009-11-11 19:13:48 +00:00
Daniel Dunbar
a45cf5b6b0 Rename clang to clang-cc.
Tests and drivers updated, still need to shuffle dirs.

llvm-svn: 67602
2009-03-24 02:24:46 +00:00
Douglas Gregor
79cf603428 Extend the notion of active template instantiations to include the
context of a template-id for which we need to instantiate default
template arguments.

In the TextDiagnosticPrinter, don't suppress the caret diagnostic if
we are producing a non-note diagnostic that follows a note diagnostic
with the same location, because notes are (conceptually) a part of the
warning or error that comes before them.

llvm-svn: 66572
2009-03-10 20:44:00 +00:00
Douglas Gregor
463421deb1 Implement the basics of implicit instantiation of class templates, in
response to attempts to diagnose an "incomplete" type. This will force
us to use DiagnoseIncompleteType more regularly (rather than looking at
isIncompleteType), but that's also a good thing.

Implicit instantiation is still very simplistic, and will create a new
definition for the class template specialization (as it should) but it
only actually instantiates the base classes and attaches
those. Actually instantiating class members will follow. 

Also, instantiate the types of non-type template parameters before
checking them,  allowing, e.g., 

  template<typename T, T Value> struct Constant; 
 
to work properly.

llvm-svn: 65924
2009-03-03 04:44:36 +00:00