[REF] web, *: review the assets helpers organization

* survey, website_slides

While not changing their name or their amount, this commit reorganizes
the assets helpers to:

Avoid all file duplicates in different helpers
----------------------------------------------

Before, we had to put some files in different helpers, like our
bootstrap mixin overrides which were in the _assets_utils template and
in the _assets_bootstrap template.

Enforce the use of an helper when using bootstrap
-------------------------------------------------

Bootstrap functions, variables and mixins are now out of the
_assets_bootstrap template, which now only contains bootstrap css rules
and our bootstrap fixes and extensions.

Allow using the correct bootstrap utils in all assets
-----------------------------------------------------

In some assets (especially editor ones), we may want to use bootstrap
variables even though bootstrap is not included in those. This worked
before but using *default* bootstrap variables. Now, our overrides can
be properly included if necessary.

Note: this commit may also be a first step to allow for backend
bootstrap and frontend bootstrap to co-exist.

closes odoo/odoo#28204

4 files changed, 25 insertions, 31 deletions

diff --git a/addons/web/static/src/scss/import_bootstrap_part2.scss b/addons/web/static/src/scss/import_bootstrap.scss
index c15793019ad..d3d033a3575 100644
--- a/addons/web/static/src/scss/import_bootstrap_part2.scss
+++ b/addons/web/static/src/scss/import_bootstrap.scss
@@ -1,11 +1,14 @@
 
 // This file is importing bootstrap. While a simple "import "bootstrap";"
-// should be enough, this does not allow overridding mixins. Overridding mixins
-// is necessary for some of our need and allow to generate more efficient CSS
-// than adding more rules. This file instead copies the second part of the
-// content of the "bootstrap.scss" files to allow adding mixin overrides in
-// between.
+// should be enough, this does not allow overridding mixins/functions.
+// Overridding those is necessary for some of our need and allow to generate
+// more efficient CSS than adding more rules. This file instead copies the
+// content of the "bootstrap.scss" files but do not import functions, variables
+// and mixins which will be handled "by hand" in _assets_helpers.
 
+// @import "functions";
+// @import "variables";
+// @import "mixins";
 @import "root";
 @import "reboot";
 @import "type";
diff --git a/addons/web/static/src/scss/import_bootstrap_part1.scss b/addons/web/static/src/scss/import_bootstrap_part1.scss
deleted file mode 100644
index 09f4d3579ac..00000000000
--- a/addons/web/static/src/scss/import_bootstrap_part1.scss
+++ /dev/null
@@ -1,11 +0,0 @@
-
-// This file is importing bootstrap. While a simple "import "bootstrap";"
-// should be enough, this does not allow overridding mixins. Overridding mixins
-// is necessary for some of our need and allow to generate more efficient CSS
-// than adding more rules. This file instead copies the first part of the
-// content of the "bootstrap.scss" files to allow adding mixin overrides in
-// between.
-
-@import "functions";
-@import "variables";
-@import "mixins";
diff --git a/addons/web/views/report_templates.xml b/addons/web/views/report_templates.xml
index 7cd5b04a01f..b33f89cd929 100644
--- a/addons/web/views/report_templates.xml
+++ b/addons/web/views/report_templates.xml
@@ -3,10 +3,11 @@
     <!-- Assets for reports -->
 
     <template id="report_assets_common">
-        <t t-call="web._assets_helpers"><t t-set="no_bs_vars" t-value="True"/></t>
+        <t t-call="web._assets_helpers">
+            <!-- FIXME web_editor ? -->
+            <link rel="stylesheet" type="text/scss" href="/web_editor/static/src/scss/bootstrap_overridden.scss"/>
+        </t>
 
-        <!-- FIXME web_editor ? -->
-        <link rel="stylesheet" type="text/scss" href="/web_editor/static/src/scss/bootstrap_overridden.scss"/>
         <t t-call="web._assets_bootstrap"/>
 
         <link href="/base/static/src/css/description.css" rel="stylesheet" type="text/css"/>
diff --git a/addons/web/views/webclient_templates.xml b/addons/web/views/webclient_templates.xml
index fa0ecce61e6..1ce0a83f63b 100644
--- a/addons/web/views/webclient_templates.xml
+++ b/addons/web/views/webclient_templates.xml
@@ -3,8 +3,10 @@
     <template id="_assets_utils">
         <link rel="stylesheet" type="text/scss" href="/web/static/lib/bootstrap/scss/_functions.scss"/>
         <link rel="stylesheet" type="text/scss" href="/web/static/lib/bootstrap/scss/_mixins.scss"/>
-        <link rel="stylesheet" type="text/scss" href="/web/static/src/scss/utils.scss"/>
+
         <link rel="stylesheet" type="text/scss" href="/web/static/src/scss/bs_mixins_overrides.scss"/>
+
+        <link rel="stylesheet" type="text/scss" href="/web/static/src/scss/utils.scss"/>
     </template>
 
     <template id="_assets_primary_variables">
@@ -20,26 +22,21 @@
         <t t-call="web._assets_primary_variables"/>
         <t t-call="web._assets_secondary_variables"/>
 
-        <!-- Bootstrap variables should not be necessary, all pages come with bootstrap in at least one of their -->
-        <!-- bundle and, ideally, these should be available in all assets... with their odoo override. This system -->
-        <!-- however works for now as non-backend and non-frontend assets do not need overriden BS variables yet. -->
-        <link t-if="not no_bs_vars" rel="stylesheet" type="text/scss" href="/web/static/lib/bootstrap/scss/_variables.scss"/>
+        <t t-raw="0"/>
+
+        <link rel="stylesheet" type="text/scss" href="/web/static/lib/bootstrap/scss/_variables.scss"/>
     </template>
 
     <template id="_assets_backend_helpers">
-        <t t-call="web._assets_helpers"><t t-set="no_bs_vars" t-value="True"/></t>
         <link rel="stylesheet" type="text/scss" href="/web/static/src/scss/bootstrap_overridden.scss"/>
     </template>
 
     <template id="_assets_frontend_helpers">
-        <t t-call="web._assets_helpers"><t t-set="no_bs_vars" t-value="True"/></t>
         <link rel="stylesheet" type="text/scss" href="/web/static/src/scss/bootstrap_overridden_frontend.scss"/>
     </template>
 
     <template id="_assets_bootstrap">
-        <link rel="stylesheet" type="text/scss" href="/web/static/src/scss/import_bootstrap_part1.scss"/>
-        <link rel="stylesheet" type="text/scss" href="/web/static/src/scss/bs_mixins_overrides.scss"/>
-        <link rel="stylesheet" type="text/scss" href="/web/static/src/scss/import_bootstrap_part2.scss"/>
+        <link rel="stylesheet" type="text/scss" href="/web/static/src/scss/import_bootstrap.scss"/>
         <link rel="stylesheet" type="text/scss" href="/web/static/src/scss/bootstrap_review.scss"/>
     </template>
 
@@ -141,7 +138,9 @@
     </template>
 
     <template id="assets_backend" name="Backend Assets (used in backend interface)">
-        <t t-call="web._assets_backend_helpers"/>
+        <t t-call="web._assets_helpers">
+            <t t-call="web._assets_backend_helpers"/>
+        </t>
 
         <t t-call="web._assets_bootstrap"/>
         <link rel="stylesheet" type="text/scss" href="/web/static/lib/tempusdominus/tempusdominus.scss"/>
@@ -316,7 +315,9 @@
     </template>
 
     <template id="web.assets_frontend" name="Website Assets">
-        <t t-call="web._assets_frontend_helpers"/>
+        <t t-call="web._assets_helpers">
+            <t t-call="web._assets_frontend_helpers"/>
+        </t>
 
         <t t-call="web._assets_bootstrap"/>
         <link rel="stylesheet" type="text/scss" href="/web/static/lib/tempusdominus/tempusdominus.scss"/>