dev: add support for dev generate cgo

The contents of these files here is basically cargo-culted from the
`Makefile`. I have verified that I can get a build working via the
following steps:

    ./dev generate go cgo
    ./dev go -- build ./pkg/cmd/cockroach-short

We don't exactly mirror the previous contents of the `zcgo_flags.go`
files that `make` would create. One difference is that we don't populate
the `zcgo_flags` files in `go-libedit` to configure how the C sources
are built and linked, so we get the default behavior, which is fine, but
means the `go build`-built binary and the Bazel-built binary will be
using a different compiled archive (maybe compiled with different flags/
a different configuration/etc.) for the `libedit` sources.

With `make`, we address this by putting a `zcgo_flags_extra.go` file in
the sources for `go-libedit` right in `vendor`. Post-Bazel we have no
reason for `vendor` and have no plans to keep it in the long-term so
this is not really suitable. I'm punting on this for now -- the default
behavior will probably be "good enough" for most people.

Closes #77170.

Release note: None

Makefile

@@ -549,6 +549,9 @@ native-tag := $(subst -,_,$(TARGET_TRIPLE))$(if $(use-stdmalloc),_stdmalloc)
 # encounters a given native tag or when the build signature changes (see
 # build/defs.mk.sig). These tags are unset when building with the Go toolchain
 # directly, so these files are only compiled when building with Make.
+#
+# NB: If you update the zcgo_flags.go generation below, make sure to make the
+# corresponding changes to `dev generate cgo`.
 CGO_PKGS := \
 	pkg/cli \
 	pkg/cli/clisqlshell \

dev

@@ -3,7 +3,7 @@
 set -euo pipefail
 
 # Bump this counter to force rebuilding `dev` on all machines.
-DEV_VERSION=27
+DEV_VERSION=28
 
 THIS_DIR=$(cd "$(dirname "$0")" && pwd)
 BINARY_DIR=$THIS_DIR/bin/dev-versions

pkg/cmd/dev/generate.go

@@ -15,6 +15,8 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"runtime"
+	"text/template"
 
 	"github.com/spf13/cobra"
 )
@@ -29,13 +31,21 @@ func makeGenerateCmd(runE func(cmd *cobra.Command, args []string) error) *cobra.
 		Use:     "generate [target..]",
 		Aliases: []string{"gen"},
 		Short:   `Generate the specified files`,
-		Long:    `Generate the specified files.`,
+		Long: `Generate the specified files.
+` + "`dev generate bazel`" + ` updates BUILD.bazel files and other Bazel files like DEPS.bzl.
+Use the --mirror option if vendoring a new dependency that needs to be mirrored.
+` + "`dev generate go`" + ` populates the workspace with generated code.
+` + "`dev generate docs`" + ` updates generated documentation.
+` + "`dev generate go+docs`" + ` does the same as ` + "`dev generate go docs`" + `, but slightly faster.
+` + "`dev generate cgo`" + ` populates the workspace with a few zcgo_flags.go files that can prepare non-Bazel build systems to link in our C dependencies.
+` + "`dev generate protobuf`" + ` generates a subset of the code that ` + "`dev generate go`" + ` does, specifically the .pb.go files.`,
 		Example: `
         dev generate
         dev generate bazel
         dev generate docs
         dev generate go
         dev generate protobuf
+        dev generate cgo
         dev generate go+docs
 `,
 		Args: cobra.MinimumNArgs(0),
@@ -52,6 +62,7 @@ func makeGenerateCmd(runE func(cmd *cobra.Command, args []string) error) *cobra.
 func (d *dev) generate(cmd *cobra.Command, targets []string) error {
 	var generatorTargetMapping = map[string]func(cmd *cobra.Command) error{
 		"bazel":    d.generateBazel,
+		"cgo":      d.generateCgo,
 		"docs":     d.generateDocs,
 		"go":       d.generateGo,
 		"protobuf": d.generateProtobuf,
@@ -149,3 +160,64 @@ func (d *dev) generateRedactSafe(ctx context.Context) error {
 		filepath.Join(workspace, "docs", "generated", "redact_safe.md"), string(output),
 	)
 }
+
+func (d *dev) generateCgo(cmd *cobra.Command) error {
+	ctx := cmd.Context()
+	args := []string{"build", "//c-deps:libjemalloc", "//c-deps:libproj", "//c-deps:libgeos"}
+	if runtime.GOOS == "linux" {
+		args = append(args, "//c-deps:libkrb5")
+	}
+	logCommand("bazel", args...)
+	if err := d.exec.CommandContextInheritingStdStreams(ctx, "bazel", args...); err != nil {
+		return err
+	}
+	bazelBin, err := d.getBazelBin(ctx)
+	if err != nil {
+		return err
+	}
+	workspace, err := d.getWorkspace(ctx)
+	if err != nil {
+		return err
+	}
+	const cgoTmpl = `// GENERATED FILE DO NOT EDIT
+
+package {{ .Package }}
+
+// #cgo CPPFLAGS: {{ .CPPFlags }}
+// #cgo LDFLAGS: {{ .LDFlags }}
+import "C"
+`
+
+	tpl := template.Must(template.New("source").Parse(cgoTmpl))
+	cppFlags := fmt.Sprintf("-I%s", filepath.Join(bazelBin, "c-deps/libjemalloc/include"))
+	ldFlags := fmt.Sprintf("-L%s -L%s", filepath.Join(bazelBin, "c-deps/libjemalloc/lib"), filepath.Join(bazelBin, "c-deps/libproj/lib"))
+	if runtime.GOOS == "linux" {
+		cppFlags += fmt.Sprintf(" -I%s", filepath.Join(bazelBin, "c-deps/libkrb5/include"))
+		ldFlags += fmt.Sprintf(" -L%s", filepath.Join(bazelBin, "c-deps/libkrb5/lib"))
+	}
+
+	cgoPkgs := []string{
+		"pkg/cli",
+		"pkg/cli/clisqlshell",
+		"pkg/server/status",
+		"pkg/ccl/gssapiccl",
+		"pkg/geo/geoproj",
+	}
+
+	for _, cgoPkg := range cgoPkgs {
+		out, err := os.Create(filepath.Join(workspace, cgoPkg, "zcgo_flags.go"))
+		if err != nil {
+			return err
+		}
+		err = tpl.Execute(out, struct {
+			Package  string
+			CPPFlags string
+			LDFlags  string
+		}{Package: filepath.Base(cgoPkg), CPPFlags: cppFlags, LDFlags: ldFlags})
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}