Fmt wrappers (more) by tomc271 · Pull Request #3514 · boutproject/BOUT-dev

tomc271 · 2026-10-15T10:29:39Z

Fix: Don't call format_as() directly
Rename the toString() functions generated by BOUT_ENUM_CLASS macro to format_as()
Replace more toString() calls with fmt::to_string()`
Replace {:s} with {}
Restore basic toString() function for Field types (and disable the fmt range formatter)
A few other fixes

so that {fmt} will not treat them as ranges so that it uses `format_as()`` instead.

instead of `format_as()` Disable the range formatter for Array, Matrix, and Tensor (so that {fmt} will not treat them as ranges so that it uses `format_as()`` instead).

alongside the enum class and operator<<. This resolves ADL name lookup failures where operator<< failed to resolve the correct `format_as()` overload for namespaced enum classes.

as automatically generated by macro.

Type-specific format specifiers not always supported now that `toString()` is not being explicitly called.

Move `std::enable_if_t` to the third template parameter (Enable). Also use `std::remove_cv_t` to ensure the trait matches const fields. This prevents {fmt} from ignoring the custom formatter and throwing compile-time "invalid format specifier" errors.

…ustom `fmt::formatter` specializations rather than format_as overloads.

Type-specific format specifiers not always supported now that `toString()` is not being explicitly called.

Include headers directly Reorder various things Whitespace changes

so that {fmt} will not treat them as ranges so that it uses `format_as()`` instead.

Make it a const ref to match the definition in the header.

dschwoerer · 2026-10-15T10:35:50Z

It would be nice if functions would first be deprecated for a release, before they get removed.
Would that be a lot of extra work?

github-actions

clang-tidy made some suggestions

github-actions · 2026-10-15T10:36:33Z

-  inline std::ostream& operator<<(std::ostream& out, const enumname& e) {          \
-    return out << toString(e);                                                     \
-  }                                                                                \
+#define BOUT_ENUM_CLASS_NS(ns, enumname, ...)                                  \


warning: variadic macro 'BOUT_ENUM_CLASS_NS' used; consider using a 'constexpr' variadic template function [cppcoreguidelines-macro-usage]

#define BOUT_ENUM_CLASS_NS(ns, enumname, ...) \ ^

github-actions · 2026-10-15T10:36:33Z

 inline bout::FieldMetric Grad_par(const Field2D& var, CELL_LOC outloc,
                                  DIFF_METHOD method) {
-  return Grad_par(var, outloc, toString(method));
+  return Grad_par(var, outloc, fmt::to_string(method));


warning: no header providing "fmt::to_string" is directly included [misc-include-cleaner]

include/bout/difops.hxx:38:

- #include "bout/bout_enum_class.hxx" + #include "fmt/format.h" + #include "bout/bout_enum_class.hxx"

github-actions · 2026-10-15T10:36:33Z

 #include "bout/region.hxx"

+#include "fmt/format.h"
+#include <fmt/base.h>


warning: included header format.h is not used directly [misc-include-cleaner]

Suggested change

#include <fmt/base.h>

#include <fmt/base.h>

github-actions · 2026-10-15T10:36:33Z


+#include "fmt/format.h"
+#include <fmt/base.h>
+#include <fmt/core.h>


warning: included header base.h is not used directly [misc-include-cleaner]

Suggested change

#include <fmt/core.h>

#include <fmt/core.h>

github-actions · 2026-10-15T10:36:33Z

+#pragma once

+#include "fmt/base.h"
+#include "fmt/format.h"


warning: included header base.h is not used directly [misc-include-cleaner]

Suggested change

#include "fmt/format.h"

#include "fmt/format.h"

github-actions · 2026-10-15T10:36:34Z


-void printLocation(const Field3D& var) { output << toString(var.getLocation()); }
-void printLocation(const Field2D& var) { output << toString(var.getLocation()); }
+void printLocation(const Field3D& var) { output << fmt::to_string(var.getLocation()); }


warning: no header providing "fmt::to_string" is directly included [misc-include-cleaner]

src/mesh/interpolation_xz.cxx:25:

- #include "parallel/fci_comm.hxx" + #include "fmt/format.h" + #include "parallel/fci_comm.hxx"

github-actions · 2026-10-15T10:36:34Z

-void printLocation(const Field3D& var) { output << toString(var.getLocation()); }
-void printLocation(const Field2D& var) { output << toString(var.getLocation()); }
+void printLocation(const Field3D& var) { output << fmt::to_string(var.getLocation()); }
+void printLocation(const Field2D& var) { output << fmt::to_string(var.getLocation()); }


warning: function 'printLocation' can be made static or moved into an anonymous namespace to enforce internal linkage [misc-use-internal-linkage]

Suggested change

void printLocation(const Field2D& var) { output << fmt::to_string(var.getLocation()); }

static void printLocation(const Field2D& var) { output << fmt::to_string(var.getLocation()); }

github-actions · 2026-10-15T10:36:34Z

  Timer time("io");
  const std::string loc_string =
-      (location == CELL_CENTRE) ? "" : "_" + toString(location);
+      (location == CELL_CENTRE) ? "" : "_" + fmt::to_string(location);


warning: no header providing "CELL_CENTRE" is directly included [misc-include-cleaner]

(location == CELL_CENTRE) ? "" : "_" + fmt::to_string(location); ^

github-actions · 2026-10-15T10:36:34Z

  Timer time("io");
  const std::string loc_string =
-      (location == CELL_CENTRE) ? "" : "_" + toString(location);
+      (location == CELL_CENTRE) ? "" : "_" + fmt::to_string(location);


warning: no header providing "fmt::to_string" is directly included [misc-include-cleaner]

src/mesh/parallel/shiftedmetric.cxx:8:

- #include "bout/paralleltransform.hxx" + #include "fmt/format.h" + #include "bout/paralleltransform.hxx"

github-actions · 2026-10-15T10:36:34Z

  output_error.write(
      "acoef={:s} bcoef={:s} ccoef={:s} dcoef={:s} ecoef{:s} with {:s} at {:s} ...",
-      acoef, bcoef, ccoef, dcoef, ecoef, func, toString(location));
+      acoef, bcoef, ccoef, dcoef, ecoef, func, fmt::to_string(location));


warning: no header providing "fmt::to_string" is directly included [misc-include-cleaner]

tests/integrated/test-invpar/test_invpar.cxx:5:

- #include <bout/bout.hxx> + #include "fmt/format.h" + #include <bout/bout.hxx>

ZedThree · 2026-10-15T12:13:07Z

I thought the plan as discussed was to move the implementations to format_as, make toString call format_as, and then deprecate toString?

tomc271 · 2026-10-15T13:01:58Z

I thought the plan as discussed was to move the implementations to format_as, make toString call format_as, and then deprecate toString?

Yes that's right, athough I also asked about whether to try replacing the existing toString calls with fmt::to_string, and I think you said yes to that?

(Rather than calling format_as directly, I think that one is supposed to use fmt:: to_string (or fmt::format or fmt::print, etc)).

Define `Options options;` above `FieldFactory factory;` so that C++ destroys them in the correct order when the test finishes.

ZedThree · 2026-10-15T16:10:40Z

Yes that's right, athough I also asked about whether to try replacing the existing toString calls with fmt::to_string, and I think you said yes to that?

Yes, replace the calls not the function :)

on field types and Options.

…erp.cxx

on field types

tomchapman added 26 commits October 15, 2026 11:10

Rename all String() with format_as()`

02d80af

Disable the range formatter for Field types

ef70e85

so that {fmt} will not treat them as ranges so that it uses `format_as()`` instead.

Use a fmt::formatter for Field2D, Field3D, FieldPerp

415a5a6

instead of `format_as()` Disable the range formatter for Array, Matrix, and Tensor (so that {fmt} will not treat them as ranges so that it uses `format_as()`` instead).

Replace more toSring() calls with format_as()

b13c455

Move format_as() inside namespace ns in BOUT_ENUM_CLASS_NS

c032889

alongside the enum class and operator<<. This resolves ADL name lookup failures where operator<< failed to resolve the correct `format_as()` overload for namespaced enum classes.

Replace more toSring() calls with format_as()

d77ca70

Remove format_as() for ConductionMethod

e074c09

as automatically generated by macro.

Replace {:s} with {}

dcf4f06

Type-specific format specifiers not always supported now that `toString()` is not being explicitly called.

Replace more toString() calls with format_as()

c0cbb88

Delete catch-all format_as template from utils.hxx

bc87893

Remove redundant comments

255b81b

Replace calls to format_as() with fmt::to_string for types with c…

e0d838a

…ustom `fmt::formatter` specializations rather than format_as overloads.

Wrap generic fmt::formatter for Fields in fmt namespace

2a5f3ec

Replace calls to format_as() with fmt::to_string for types with c…

1db89a8

…ustom `fmt::formatter` specializations rather than format_as overloads.

No need to call format_as() with BoutException

dff473e

Call fmt::to_string() or fmt::format() not format_as()

17cfc84

Replace {:s} with {}

eaa3a6a

Type-specific format specifiers not always supported now that `toString()` is not being explicitly called.

Remove namespace and qualify class name

3682624

Remove format_as() functions for std::string and bool types

7fe4256

Minor tidying:

18e1b25

Include headers directly Reorder various things Whitespace changes

Restore toString() for fields

8fb5952

Disable the range formatter for Field types

f1ee685

so that {fmt} will not treat them as ranges so that it uses `format_as()`` instead.

Fix signature of format_as() for DIFF_METHOD

62f2b3b

Make it a const ref to match the definition in the header.

Apply clang-format

b36200f

Add missing header

bc1e7ec

github-actions Bot reviewed Oct 15, 2026

View reviewed changes

tomchapman added 2 commits October 15, 2026 11:38

Remove more toString() calls

abc0a66

Restore toString() for booleans

01ee06c

Restore original function order

8080e6e

Fix FieldFactoryCreationTest

3963b9e

Define `Options options;` above `FieldFactory factory;` so that C++ destroys them in the correct order when the test finishes.

tomchapman added 7 commits October 16, 2026 13:18

Replace toString with fmt::to_string for operator<<

a568f2e

on field types and Options.

Call fmt::to_string on enums when using in the argument to EXPECT_EQ.

7dc1724

Include output_bout_types.hxx in field2d.cxx, field3d.cxx, and fieldp…

fca0e8c

…erp.cxx

Restore use of toString() in StringUtilitiesTests

6affe3f

Restore use of toString() in OptionsTest

ad7344a

Revert replace toString with fmt::to_string for operator<<

0f85800

on field types

Replace one more toString with fmt::to_string

eba7b8c

tomc271 marked this pull request as ready for review October 19, 2026 10:00

	void printLocation(const Field2D& var) { output << fmt::to_string(var.getLocation()); }
	static void printLocation(const Field2D& var) { output << fmt::to_string(var.getLocation()); }

Conversation

tomc271 commented Oct 15, 2026

Uh oh!

dschwoerer commented Oct 15, 2026

Uh oh!

github-actions Bot left a comment

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Oct 15, 2026

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Oct 15, 2026

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Oct 15, 2026

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Oct 15, 2026

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Oct 15, 2026

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Oct 15, 2026

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Oct 15, 2026

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Oct 15, 2026

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Oct 15, 2026

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Oct 15, 2026

Choose a reason for hiding this comment

Uh oh!

ZedThree commented Oct 15, 2026

Uh oh!

tomc271 commented Oct 15, 2026

Uh oh!

ZedThree commented Oct 15, 2026

Uh oh!

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants